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  • 51. Cong, Jiayan
    et al.
    Yang, Xichuan
    Hao, Yan
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi (stängd 20110630).
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    A highly efficient colourless sulfur/iodide-based hybrid electrolyte for dye-sensitized solar cells2012Inngår i: RSC Advances, ISSN 2046-2069, Vol. 2, nr 9, s. 3625-3629Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new kind of hybrid electrolyte with S2-/S-x(2-) and I- was invented, and the new hybrid system was demonstrated to outperform the well-known I-/I-3(-) redox system in DSCs. An efficiency of 9.1% was achieved in our lab under AM 1.5 illumination using the dye N719, considerably higher than the efficiency of 8.0% of the I-/I-3(-)-based electrolyte.

  • 52. Cong, Jiayan
    et al.
    Yang, Xichuan
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Iodine/iodide-free redox shuttles for liquid electrolyte-based dye-sensitized solar cells2012Inngår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 5, nr 11, s. 9180-9194Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Dye-sensitized solar cells have attracted intense academic interest over the past two decades. For a long time, the development of new redox systems has fallen far behind that of the sensitizing dyes and other materials. However, the field has received renewed attention recently. In particular, in 2011, the Gratzel group published a record DSC efficiency of 12.3% by using a new Co-complex-based electrolyte. In this review, we will provide an overview of iodine/iodide-free redox systems for liquid electrolytes, and reveal that the design of an efficient redox system should combine with appropriate sensitizing dyes which is the pivotal challenge for highly efficient DSCs.

  • 53.
    Cong, Jiayan
    et al.
    Dalian Univ Technol, Dalian, Peoples R China.
    Yang, Xichuan
    Dalian Univ Technol, Dalian, Peoples R China.
    Liu, Jing
    Dalian Univ Technol, Dalian, Peoples R China.
    Zhao, Jinxia
    Dalian Univ Technol, Dalian, Peoples R China.
    Hao, Yan
    Dalian Univ Technol, Dalian, Peoples R China.
    Wang, Yu
    Dalian Univ Technol, Dalian, Peoples R China.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Nitro group as a new anchoring group for organic dyes in dye-sensitized solar cells2012Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 48, nr 53, s. 6663-6665Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An organic dye JY1 bearing a nitro group was designed, synthesized and applied in DSCs. An unusual colour change was observed when the voltage applied to the device was reversed which was accompanied by a five-fold increase in the cell efficiency. We propose that applying a bias enabled the attachment of nitro groups to the TiO2 surface.

  • 54. Cui, Hong-Guang
    et al.
    Wang, Mei
    Dong, Wei-Bing
    Duan, Le-Le
    Li, Ping
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Synthesis, structures and electrochemical properties of hydroxyl- and pyridyl-functionalized diiron azadithiolate complexes2007Inngår i: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719, Vol. 26, nr 4, s. 904-910Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hydroxyl- and pyridyl-functionalized diiron azadithiolate complexes [[(mu-SCH2)(2)N(CH2CH2OH)}Fe-2(CO)(6)] (1) and [{(mu-SCH2)(2)N(CH2CH2OOCPy)} Fe-2(CO)(6)] (Py = pyridyl) (2) were prepared as biomimetic models of the active site of Fe-only hydrogenases. Both complexes were characterized by MS, IR, H-1 NMR spectra and elemental analysis. The molecular structures of 1 and 2 were determined by single crystal X-ray analysis. A network is constructed by intermolecular H-bonds in the crystals of 1. An S center dot center dot center dot O intermolecular contact was found in the crystals of 2, which is scarcely found for organometallic complexes. Cyclic voltammograms of 1 and 2 were studied to evaluate their redox properties.

  • 55. Cui, Hongguang
    et al.
    Wang, Mei
    Duan, Lele
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Preparation, characterization and electrochemistry of an iron-only hydrogenase active site model covalently linked to a ruthenium tris(bipyridine) photosensitizer2008Inngår i: Journal of coordination chemistry (Print), ISSN 0095-8972, E-ISSN 1029-0389, Vol. 61, nr 12, s. 1856-1861Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An NH2-functionlized [Fe2S2] model complex of the iron-only hydrogenase active site was covalently linked to the tris( bipyridine) ruthenium photosensitizer. The [RuFeFe] trinuclear complex 1 was characterized by MS, IR, UV-vis, H-1 & C-13 NMR spectra. A quasi-reversible reduction peak at - 1.41V versus Ag/Ag+ for the (FeFeI)-Fe-I/(FeFe0)-Fe-I process is observed in the cyclic voltammogram of 1.

  • 56. D'Amario, Luca
    et al.
    Jiang, Roger
    Cappel, Ute B.
    Gibson, Elizabeth A.
    Boschloo, Gerrit
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Rensmo, Hakan
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Hammarstrom, Leif
    Tian, Haining
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Chemical and Physical Reduction of High Valence Ni States in Mesoporous NiO Film for Solar Cell Application2017Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, nr 39, s. 33470-33477Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The most common material for dye-sensitized photocathodes is mesoporous NiO. We transformed the usual brownish NiO to be more transparent by reducing high valence Ni impurities. Two pretreatment methods have been used: chemical reduction by NaBH4 and thermal reduction by heating. The power conversion efficiency of the cell was increased by 33% through chemical treatment, and an increase in open-circuit voltage from 105 to 225 mV was obtained upon heat treatment. By optical spectroelectrochemistry, we could identify two species with characteristically different spectra assigned to Ni3+ and Ni4+. We suggest that the reduction of surface Ni3+ and Ni (4+) to Ni (2+) decreases the recombination reaction between holes on the NiO surface with the electrolyte. It also keeps the dye firmly on the surface, building a barrier for electrolyte recombination. This causes an increase in open-circuit photovoltage for the treated film.

  • 57.
    Daniel, Quentin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Anabre, Ram B.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Zhang, Biaobiao
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Philippe, Bertrand
    Chen, Hong
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Li, Fusheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Fan, Ke
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ahmadi, Sareh
    Rensmo, Hakan
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Dalian University of Technology (DUT), China.
    Re-Investigation of Cobalt Porphyrin for Electrochemical Water Oxidation on FTO Surface: Formation of CoOx as Active Species2017Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, nr 2, s. 1143-1149Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of cobalt porphyrin complexes as efficient and cost-effective molecular catalysts for water oxidation has been investigated previously. However, by combining a set of analytical techniques (electrochemistry, ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and synchrotron-based photoelectron spectroscopy (SOXPES and HAXPES)), we have demonstrated that three different cobalt porphyrins, deposited on FTO glasses, decompose promptly into a thin film of CoOx on the surface of the electrode during water oxidation under certain conditions (borate buffer pH 9.2). It is presumed that the film is composed of CoO, only detectable by SOXPES, as conventional techniques are ineffective. This newly formed film has a high turnover frequency (TOF), while the high transparency of the CoOx-based electrode is very promising for future application in photoelectrochemical cells.

  • 58.
    Daniel, Quentin
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Duan, Lele
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Timmer, Brian J. J.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Chen, Hong
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Luo, Xiaodan
    Peking Univ, Coll Chem & Mol Engn, Beijing 100871, Peoples R China..
    Ambre, Ram
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Wang, Ying
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Zhang, Biaobiao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Zhang, Peili
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Wang, Lei
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Li, Fusheng
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Sun, Junliang
    Peking Univ, Coll Chem & Mol Engn, Beijing 100871, Peoples R China..
    Ahlquist, Mårten S. G.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Water Oxidation Initiated by In Situ Dimerization of the Molecular Ru(pdc) Catalyst2018Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, nr 5, s. 4375-4382Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mononuclear ruthenium complex [Ru(pdc)L-3] (H(2)pdc = 2,6-pyridinedicarboxylic acid, L = N-heterocycles such as 4-picoline) has previously shown promising catalytic efficiency toward water oxidation, both in homogeneous solutions and anchored on electrode surfaces. However, the detailed water oxidation mechanism catalyzed by this type of complex has remained unclear. In order to deepen understanding of this type of catalyst, in the present study, [Ru(pdc)(py)(3)] (py = pyridine) has been synthesized, and the detailed catalytic mechanism has been studied by electrochemistry, UV-vis, NMR, MS, and X-ray crystallography. Interestingly, it was found that once having reached the Ru-IV state, this complex promptly formed a stable ruthenium dimer [Ru-III(pdc)(py)(2)-O-Ru-IV(pdc)(py)(2)](+). Further investigations suggested that the present dimer, after one pyridine ligand exchange with water to form [Ru-III(pdc)(py)(2)-O-Ru-IV(pdc)(py)(H2O)](+), was the true active species to catalyze water oxidation in homogeneous solutions.

  • 59.
    Daniel, Quentin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Huang, Ping
    Fan, Ting
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Wang, Ying
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Duan, Lele
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Wang, Lei
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Li, Fusheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Rinkevicius, Zilvinas
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ahlquist, Mårten S. G.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Mamedov, Fikret
    Styring, Stenbjörn
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Rearranging from 6-to 7-coordination initiates the catalytic activity: An EPR study on a Ru-bda water oxidation catalyst2017Inngår i: Coordination chemistry reviews, ISSN 0010-8545, E-ISSN 1873-3840, Vol. 346, s. 206-215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The coordination of a substrate water molecule on a metal centered catalyst for water oxidation is a crucial step involving the reorganization of the ligand sphere. This process can occur by substituting a coordinated ligand with a water molecule or via a direct coordination of water onto an open site. In 2009, we reported an efficient ruthenium-based molecular catalyst, Ru-bda, for water oxidation. Despite the impressive improvement in catalytic activity of this type of catalyst over the past years, a lack of understanding of the water coordination still remains. Herein, we report our EPR and DFT studies on Ru-bda (triethylammonium 3-pyridine sulfonate)(2) (1) at its Ru-III oxidation state, which is the initial state in the catalytic cycle for the O-O bond formation. Our investigation suggests that at this III-state, there is already a rearrangement in the ligand sphere where the coordination of a water molecule at the 7th position (open site) takes place under acidic conditions (pH = 1.0) to form a rare 7-coordinated Ru-III species.

  • 60.
    Daniel, Quentin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Wang, Lei
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Duan, Lele
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Li, Fusheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Dalian Univ Technol, Peoples R China.
    Tailored design of ruthenium molecular catalysts with 2,2 '-bypyridine-6,6 '-dicarboxylate and pyrazole based ligands for water oxidation2016Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, nr 37, s. 14689-14696Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    With the incorporation of pyrazole and DMSO as axial ligands, a series of tailor-designed Ru water oxidation catalysts [Ru(bda)(DMSO)(L)] (H(2)bda = 2,2'-bypyridine-6,6'-dicarboxylic acid; DMSO = dimethyl sulfoxide; L = pyrazole, A-1; 4-Br-3-methyl pyrazole, B-1) and [Ru(bda)(L)(2)] (L = pyrazole, A-2; 4-Br-3-methyl pyrazole, B-2) have been generated in situ from their corresponding precursors [Ru(kappa(O,N,N)(3)-bda) (DMSO)(x)(L)(3-x)] which are in a zwitterionic form with an extra pyrazole based ligand in the equatorial position. Formation of the active catalyst has been investigated under pH 1.0 conditions. Electrochemistry and water oxidation activity of these catalysts were investigated. By fine tuning of the catalyst structure, the turnover frequency was increased up to 500 s(-1) and the stability over 6000 turnovers.

  • 61. Dau, H.
    et al.
    Fujita, E.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Artificial Photosynthesis: Beyond Mimicking Nature2017Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 22, s. 4228-4235Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this Editorial, Guest Editors Holger Dau, Etsuko Fujita, and Licheng Sun introduce the Special Issue of ChemSusChem on “Artificial Photosynthesis for Sustainable Fuels”. They discuss the need for non-fossil based fuels, introduce both biological and artificial photosynthesis, and outline various important concepts in artificial photosynthesis, including molecular and solid-state catalysts for water oxidation and hydrogen evolution, catalytic CO2 reduction, and photoelectrochemical systems.

  • 62. Detz, R. J.
    et al.
    Sakai, K.
    Spiccia, L.
    Brudvig, G. W.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Dalian University of Technology, China.
    Reek, J. N. H.
    Towards a Bioinspired-Systems Approach for Solar Fuel Devices2016Inngår i: ChemPlusChem, ISSN 2192-6506, Vol. 81, nr 10, s. 1024-1027Artikkel i tidsskrift (Fagfellevurdert)
  • 63. Ding, Xin
    et al.
    Gao, Yan
    Fan, Ting
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ji, Yongfei
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Zhang, Linlin
    Yu, Ze
    Ahlquist, Mårten S. G.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi. Dalian University of Technology (DUT), China.
    Silicon Compound Decorated Photoanode for Performance Enhanced Visible Light Driven Water Splitting2016Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 215, s. 682-688Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient dye (1) sensitized photoelectrochemical cell (DS-PEC) has been assembled with a silicon compound (3-chloropropyl) trimethoxy-silane (Si-Cl) decorated working electrode (WE) TiO2(1 + 2). The introduction of this Si-Cl molecule on photoanode leads to better performances on efficiency than untreated ones for light driven water splitting. The firm Si-O layer formed on TiO2 increased the resistance of the TiO2/catalyst interface which is assumed to decrease charge recombination from TiO2 to the oxidized catalyst 2. The work presented here provides an effective method to improve the performances of DS-PECs.

  • 64. Ding, Xin
    et al.
    Gao, Yan
    Ye, Lu
    Zhang, Linlin
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Assembling Supramolecular Dye-Sensitized Photoelectrochemical Cells for Water Splitting2015Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, nr 23, s. 3992-3995Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The method used to assemble dye-sensitized photoelectrochemical (DS-PEC) devices plays a vital role in determining its photoactivity and stability. We report a simple and effective method to assemble supramolecular DS-PECs introducing PMMA as support material and a catalyst modified with long carbon chains as photoanodes. The long carbon chains in combination with PMMA allow to better immobilize the catalyst. DS-PECs obtained by this simple method have display excellent photoactivities and stabilities. A photocurrent density of 1.1mAcm(-2) and a maximum IPCE of 9.5% have been obtained with a 0.2V vs NHE external bias.

  • 65. Ding, Xin
    et al.
    Gao, Yan
    Zhang, Linlin
    Yu, Ze
    Liu, Jianhui
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Artificial photosynthesis: A two-electrode photoelectrochemical cell for light driven water oxidation with molecular components2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 149, s. 337-340Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient two-electrode molecular PEC was assembled, in which a photoanode was constructed using a co-adsorbed method with a molecular photosensitizer (PS) 1 and a molecular catalyst 2 on TiO2-sintered FTO electrode (TiO2(1 + 2)). Without applied bias against a reference electrode, the system achieves remarkable photocurrent densities and carries out light driven water oxidation as evidenced by Clark electrode measurements in solution. A photocurrent density of 70 mA/cm(2) has been obtained within 10 s illumination time, and a TON of about 220 was obtained with a maximum turnover frequency (TOF) of ca. 4 min(-1) within the initial 5 minutes illumination duration.

  • 66. Ding, Xin
    et al.
    Gao, Yan
    Zhang, Linlin
    Yu, Ze
    Liu, Jianhui
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Visible Light-Driven Water Splitting in Photoelectrochemical Cells with Supramolecular Catalysts on Photoanodes2014Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 4, nr 7, s. 2347-2350Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    By using a supramolecular self-assembly method, a functional water splitting device based on a photoactive anode TiO2(1+2) has been successfully assembled with a molecular photosensitizer 1 and a molecular catalyst 2 connected by coordination of 1 and 2 with Zr4+ ions on the surface of nanostructured TiO2. On the basis of this photoanode in a three-electrode photoelectrochemical cell, a maximal incident photon to current conversion efficiency of 4.1% at similar to 450 nm and a photocurrent density of similar to 0.48 mA cm(-2) were successfully obtained.

  • 67. Domen, K.
    et al.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Dalian University of Technology, China .
    Editorial2013Inngår i: Catalysis Science and Technology, ISSN 2044-4753, Vol. 3, nr 7, s. 1659-Artikkel i tidsskrift (Fagfellevurdert)
  • 68. Dong, J.
    et al.
    Wang, M.
    Li, X.
    Chen, L.
    He, Y.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Simple nickel-based catalyst systems combined with graphitic carbon nitride for stable photocatalytic hydrogen production in water2012Inngår i: ChemSusChem, ISSN 1864-5631, Vol. 5, nr 11, s. 2133-2138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A molecular catalyst system containing only earth-abundant elements is combined with g-C3N4 as photosensitizer. The in situ generated complexes serve as catalysts for visible-light-driven H2 production in aqueous solution, and do not require organic solvent or a Brønsted acid. H2 evolution from the Ni-based catalyst system can be maintained for over 60 h, demonstrating that the combination is a promising approach to improve the lifetimes of molecular catalysts towards photochemical H2 production.

  • 69. Dong, Jingfeng
    et al.
    Wang, Mei
    Zhang, Pan
    Yang, Songqiu
    Liu, Jianyong
    Li, Xueqiang
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Promoting Effect of Electrostatic Interaction between a Cobalt Catalyst and a Xanthene Dye on Visible-Light-Driven Electron Transfer and Hydrogen Production2011Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, nr 30, s. 15089-15096Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The readily obtained noble-metal-free molecular catalyst systems, with xanthene dyes (Rose Bengal, RB(2-); Eosin Y, EY(2-); and Eosin B, EB(2-)) as photosensitizers, [Co(bpy)(3)]Cl(2) as catalyst, and triethylamine as sacrificial electron donor, are highly active for visible-light-driven (lambda > 450 nm) hydrogen production from water. The turnover frequency is up to 54 TON/min versus RB(2-) with a RB(2-)/[Co(bpy)(3)]Cl(2) molar ratio of 1:10 in CH(3)CN/H(2)O under optimal conditions in the first half hour of irradiation (lambda > 450 rim), and the turnover number is up to 2076 versus RB(2-). Comparative studies show the following: (1) The photocatalytic H(2)-evolving activity of the cationic cobalt complex [Co(bpy)(3)]Cl(2), is apparently higher than the neutral cobaloxime complexes with xanthene dyes as potosensitizers, and also much higher than the analogous system of [Ru(bpy)(3)]Cl(2)/[Co(bpy)(3)]Cl(2). (2) The UV-vis absorptions of xanthene dyes are red shifted to different extents upon addition of [Co(bpy)(3)]Cl(2) to the aqueous or CH(3)CN/H(2)O solutions of these dyes, while no change was observed in UV-vis absorptions of photosensitizer with addition of the cobaloximes to the aqueous solution of RB(2-) or addition of [Co(bpy)(3)]Cl(2) to the aqueous solution of [Ru(bpy)(3)]Cl(2). (3) The fluorescence of RB(2-) is significantly quenched by [Co(bpy)(3)]Cl(2), but not by the cobaloximes. These special performances of [Co(bpy)(3)]Cl(2) are attributed to the electrostatically attractive interaction between the anionic organic dyes and the cationic cobalt catalyst. The probable mechanism for photoinduced hydrogen production catalyzed by the system of RB(2-), [Co(bpy)(3)]Cl(2), and triethylamine is discussed in detail on the basis of fluorescence. fand transient absorption spectroscopic studies. "

  • 70. Dong, Weibing
    et al.
    Wang, Mei
    Liu, Tianbiao
    Liu, Xiaoyang
    Jin, Kun
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Preparation, structures and electrochemical property of phosphine substituted diiron azadithiolates relevant to the active site of Fe-only hydrogenases2007Inngår i: Journal of Inorganic Biochemistry, ISSN 0162-0134, E-ISSN 1873-3344, Vol. 101, nr 3, s. 506-513Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mono- and di-phosphine diiron azadithiolate complexes [{(mu-SCH2)(2)N(4-NO2C6H4)}Fe-2(CO)(5)(PMe3)] (2), [{(mu-SCH2)(2)N(4NO(2)C(6)H(4))} {Fe(CO)(2)L}(2)] (3, L = PMe3; 4, PMe2Ph) and the mu-hydride diiron complex [3(FeHFe)](+)[PF6](-) were prepared as biontimetic models of the active site of Fe-only hydrogenases. The complexes 2-4 and [3(FeHFe)](+)[PF6](-) were characterized by IR P-31, H-1 and C-13 NMR spectra and their molecular structures were determined by single crystal X-ray analyses. The PMe3 ligand in complex 2 lies on the basal position. The PMe3-disubstituted complex 3 exists as two configuration isomers, transoid basal/basal and apical/basal, in the crystalline state, while two PMe2Ph ligands of 4 are in an apical/basal orientation. The variable temperature P-31 NMR spectra of 2 and 3 were made to have an insight into the existence of the possible conformation isomers of 2 and 3 in solution. The [3(FeHFe)](+) cation possesses the sole transoid ba/ba geometry as other reported mu-hydride diiron analogues. The electrocatalytic property of {(mu-SCH2)(2)NC6H5}[Fe(CO)(2)PMe3](2) (5) was studied for proton reduction in the presence of HOAc.

  • 71.
    Du, Jian
    et al.
    Dalian Univ Technol, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Li, Fei
    Dalian Univ Technol, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Wang, Yong
    Dalian Univ Technol, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Zhu, Yong
    Dalian Univ Technol, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. Dalian Univ Technol, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Cu3P/CuO Core-Shell Nanorod Arrays as High-Performance Electrocatalysts for Water Oxidation2018Inngår i: Chemelectrochem, ISSN 2196-0216, Vol. 5, nr 15, s. 2064-2068Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Earth-abundant transition-metal-based oxides are potential candidates to replace the state-of-the-art noble-metal-based oxygen evolution catalysts (OECs) such as IrO2 and RuO2. Despite the low cost and large abundance, copper-based OER catalysts have been less frequently studied, mainly owing to the low electrical conductivity of copper oxides that results in large overpotential and sluggish kinetics for oxygen evolution. We report here the insitu fabrication of semi-metallic Cu3P nanorod arrays on commercial copper foam via a template approach; the resulting self-supported core-shell Cu-Cu3P/CuO electrode has the merits of high electrical conductivity, large active area, and short diffusion paths for electrolyte and evolved oxygen, exhibiting a low overpotential of 315mV and high durability over 50h at a current density of 10mAcm(-2) for OER in 1.0 M KOH. The remarkable OER performance reported here is not only superior to that of analogous Cu-CuO foam electrode, but also outperforms those of copper-based OER electrocatalysts in the literature.

  • 72.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Araujo, Carlos Moyses
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ahlquist, Mårten S. G.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Highly efficient and robust molecular ruthenium catalysts for water oxidation2012Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 109, nr 39, s. 15584-15588Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Water oxidation catalysts are essential components of light-driven water splitting systems, which could convert water to H-2 driven by solar radiation (H2O + h nu -> 1/2O(2) + H-2). The oxidation of water (H2O -> 1/2O(2) + 2H(+) + 2e(-)) provides protons and electrons for the production of dihydrogen (2H(+) + 2e(-) -> H-2), a clean-burning and high-capacity energy carrier. One of the obstacles now is the lack of effective and robust water oxidation catalysts. Aiming at developing robust molecular Ru-bda (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) water oxidation catalysts, we carried out density functional theory studies, correlated the robustness of catalysts against hydration with the highest occupied molecular orbital levels of a set of ligands, and successfully directed the synthesis of robust Ru-bda water oxidation catalysts. A series of mononuclear ruthenium complexes [Ru(bda)L-2] (L = pyridazine, pyrimidine, and phthalazine) were subsequently synthesized and shown to effectively catalyze Ce-IV-driven [Ce-IV = Ce(NH4)(2()NO3)(6)] water oxidation with high oxygen production rates up to 286 s(-1) and high turnover numbers up to 55,400.

  • 73.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Bozoglian, Fernando
    Mandal, Sukanta
    Stewart, Beverly
    Privalov, Timofei
    Llobet, Antoni
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    A molecular ruthenium catalyst with water-oxidation activity comparable to that of photosystem II2012Inngår i: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 4, nr 5, s. 418-423Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Across chemical disciplines, an interest in developing artificial water splitting to O-2 and H-2, driven by sunlight, has been motivated by the need for practical and environmentally friendly power generation without the consumption of fossil fuels. The central issue in light-driven water splitting is the efficiency of the water oxidation, which in the best-known catalysts falls short of the desired level by approximately two orders of magnitude. Here, we show that it is possible to close that 'two orders of magnitude' gap with a rationally designed molecular catalyst [Ru(bda)(isoq)(2)] (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; isoq = isoquinoline). This speeds up the water oxidation to an unprecedentedly high reaction rate with a turnover frequency of >300 s(-1). This value is, for the first time, moderately comparable with the reaction rate of 100-400 s(-1) of the oxygen-evolving complex of photosystem II in vivo.

  • 74.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Fischer, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Xu, Yunhua
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Isolated Seven-Coordinate Ru(IV) Dimer Complex with HOHOH (-) Bridging Ligand as an Intermediate for Catalytic Water Oxidation2009Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, nr 30, s. 10397-+Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    With the inspiration from an oxygen evolving complex (OEC) in Photosystern II (PSII), a mononuclear Ru(II) complex with a tetradentate ligand containing two carboxylate groups has been synthesized and structurally characterized. This Ru(II) complex showed efficient catalytic properties toward water oxidation by the chemical oxidant cerium(IV) ammonium nitrate. During the process of catalytic water oxidation, Ru(III) and Ru(IV) species have been successfully isolated as intermediates. To our surprise, X-ray crystallography together with HR-MS revealed that the Ru(IV) species is a seven-coordinate Ru(IV) dimer complex containing a [HOHOH](-) bridging ligand. This bridging ligand has a short O center dot center dot center dot O distance and is hydrogen bonded to two water molecules. The discovery of this very uncommon seven-coordinate Ru(IV) dimer together with a hydrogen bonding network may contribute to a deeper understanding of the mechanism for catalytic water oxidation. It will also provide new possibilities for the design of more efficient catalysts for water oxidation, which is the key step for solar energy conversion into hydrogen by tight-driven water splitting, the ultimate challenge in artificial photosynthesis.

  • 75.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Mandal, Sukanta
    Bozoglian, Fernando
    Stewart, Beverly
    Privalov, Timofei
    Llobet, Antoni
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    The First Replication of the Water Oxidation Activity of Photosystem-II by a Molecular Ruthenium CatalystManuskript (preprint) (Annet vitenskapelig)
  • 76.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Tong, L.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Towards the Visible Light-Driven Water Splitting Device: Ruthenium Water Oxidation Catalysts with Carboxylate-Containing Ligands2014Inngår i: Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes, Wiley-Blackwell, 2014, s. 51-76Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    The presence of oxo and carboxylate ligands is crucial to decreasing the redox potentials of the oxygen evolving complex (OEC). It has been proved that negatively charged ligands can stabilize the high oxidation states of various transition metal-based complexes and lower their oxidation potentials. This chapter focuses on complexation of transition metals primarily ruthenium (Ru) with carboxylate-containing ligands, in order to develop artificial water oxidation catalysts (WOCs) with small overpotentials. The authors aim at applying highly active and robust WOCs in artificial photosynthesis devices that convert photo energy to chemical energy. A typical visible light-driven water oxidation system consists of three components: a WOC, a photosensitizer, and a sacrificial electron acceptor. The chapter demonstrates a density functional theory (DFT)-directed development of robust Ru-WOCs, showing one of the advantages of molecular WOCs.

  • 77.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Tong, Lianpeng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Xu, Yunhua
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Visible light-driven water oxidation-from molecular catalysts to photoelectrochemical cells2011Inngår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 4, nr 9, s. 3296-3313Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This perspective article reports the most significant advances in the field of water oxidation-from molecular water oxidation catalysts (WOCs) to photoelectrochemical cells. Different series of catalysts that can be applied in visible light-driven water oxidation catalysis are discussed in details and several key aspects of their catalytic mechanisms are introduced. In order to construct a water oxidation electrode from molecular catalysts, proper immobilization methods have to be employed. Herein, we present one section about how to attach catalysts onto an electrode/material surface. Finally, the state of the art photoelectrochemical cells that achieve visible light-driven water splitting are described.

  • 78.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Wang, Lei
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Inge, A. Ken
    Fischer, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Zou, Xiaodong
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Insights into Ru-Based Molecular Water Oxidation Catalysts: Electronic and Noncovalent-Interaction Effects on Their Catalytic Activities2013Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 52, nr 14, s. 7844-7852Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of Ru-bda water oxidation catalysts [Ru(bda)L-2] (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; L = [HNEt3][3-SO3-pyridine], 1; 4-(EtOOC)-pyridine, 2; 4-bromopyridine, 3; pyridine, 4; 4-methoxypyridine, 5; 4-(Me2N)-pyridine, 6; 4-[Ph(CH2)(3)]-pyridine, 7) were synthesized with election-donating/-withdrawing groups and hydro-philic/hydrophobic groups in the axial ligands. These complexes were characterized by H-1 NMR spectroscopy, high-resolution mass spectrometry, elemental analysis, and electrochemistry. In addition, complexes 1 and 6 were further identified by single crystal X-ray crystallography, revealing a highly distorted octahedral configuration of the Ru coordination sphere. All of these complexes are highly active toward Ce-IV-driven (Ce-IV = Ce(NH4)(2)(NO3)(6)) water oxidation with oxygen evolution rates up to 119 mols of O-2 per mole of catalyst per second. Their structure-activity relationship was investigated. Electron-withdrawing and noncovalent interactions (attraction) exhibit positive effect on the catalytic activity of Ru-bda catalysts.

  • 79.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Wang, Lei
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Li, Fusheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Li, Fei
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. State Key Lab of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology (DUT), Dalian, China.
    Highly Efficient Bioinspired Molecular Ru Water Oxidation Catalysts with Negatively Charged Backbone Ligands2015Inngår i: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 48, nr 7, s. 2084-2096Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The oxygen evolving complex (OEC) of the natural photosynthesis system II (PSII) oxidizes water to produce oxygen and reducing equivalents (protons and electrons). The oxygen released from PSII provides the oxygen source of our atmosphere; the reducing equivalents are used to reduce carbon dioxide to organic products, which support almost all organisms on the Earth planet. The first photosynthetic organisms able to split water were proposed to be cyanobacteria-like ones appearing ca. 2.5 billion years ago. Since then, nature has chosen a sustainable way by using solar energy to develop itself. Inspired by nature, human beings started to mimic the functions of the natural photosynthesis system and proposed the concept of artificial photosynthesis (AP) with the view to creating energy-sustainable societies and reducing the impact on the Earth environments. Water oxidation is a highly energy demanding reaction and essential to produce reducing equivalents for fuel production, and thereby effective water oxidation catalysts (WOCs) are required to catalyze water oxidation and reduce the energy loss. X-ray crystallographic studies on PSII have revealed that the OEC consists of a Mn4CaO5 cluster surrounded by oxygen rich ligands, such as oxyl, oxo, and carboxylate ligands. These negatively charged, oxygen rich ligands strongly stabilize the high valent states of the Mn cluster and play vital roles in effective water oxidation catalysis with low overpotential. This Account describes our endeavors to design effective Ru WOCs with low overpotential, large turnover number, and high turnover frequency by introducing negatively charged ligands, such as carboxylate. Negatively charged ligands stabilized the high valent states of Ru catalysts, as evidenced by the low oxidation potentials. Meanwhile, the oxygen production rates of our Ru catalysts were improved dramatically as well. Thanks to the strong electron donation ability of carboxylate containing ligands, a seven-coordinate Ru-IV species was isolated as a reaction intermediate, shedding light on the reaction mechanisms of Ru-catalyzed water oxidation chemistry. Auxiliary ligands have dramatic effects on the water oxidation catalysis in terms of the reactivity and the reaction mechanism. For instance, Ru-bda (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) water oxidation catalysts catalyze Ce-IV-driven water oxidation extremely fast via the radical coupling of two Ru-V=O species, while Ru-pda (H(2)pda = 1,10-phenanthroline-2,9-dicarboxylic acid) water oxidation catalysts catalyze the same reaction slowly via water nucleophilic attack on a Ru-V-O species. With a number of active Ru catalysts in hands, light driven water oxidation was accomplished using catalysts with low catalytic onset potentials. The structures of molecular catalysts could be readily tailored to introduce additional functional groups, which favors the fabrication of state-of-the-art Ru-based water oxidation devices, such as electrochemical water oxidation anodes and photo-electrochemical anodes. The development of efficient water oxidation catalysts has led to a step forward in the sustainable energy system.

  • 80. Duan, Lele
    et al.
    Wang, Mei
    Li, Ping
    Wang, Ning
    Wang, Fujun
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Synthesis, protonation and electrochemical properties of trinuclear NiFe2 complexes Fe-2(CO)(6)(mu(3)-S)(2) Ni(Ph2PCH2)(2)NR (R = n-Bu, Ph) with an internal pendant nitrogen base as a proton relay2009Inngår i: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 362, nr 2, s. 372-376Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two trinuclear NiFe2 complexes Fe-2(CO)(6)(mu(3)-S)(2)[Ni(Ph2PCH2)(2)NR] (R = n-Bu, 1; Ph, 2) containing an internal base were prepared as biomimetic models for the active sites of FeFe and NiFe hydrogenases. Treatment of complex Fe-2(CO)(6)(mu(3)-S)(2)[Ni(Ph2PCH2)(2)N(n-Bu)] (1) with HOTf gave an N-protonated complex [Fe-2(CO)(6)(mu(3)-S)(2){Ni(Ph2PCH2)(2)NH(n-Bu)}][OTf] ([1H][OTf]). The structures of complexes 1, 2 and [1H][OTf] were determined by X-ray crystallography, which shows that the proton held by the N atom of [1H][OTf] lies in an equatorial position. Cyclic voltammograms of complexes 1 and [1H][OTf] were studied and compared with that of Fe-2(CO)(6)(mu(3)-S)(2)[Ni(dppe)].

  • 81.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Xu, Yunhua
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Gorlov, Mikhail
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Tong, Lianpeng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Andersson, Samir
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Chemical and Photochemical Water Oxidation Catalyzed by Mononuclear Ruthenium Complexes with a Negatively Charged Tridentate Ligand2010Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, nr 15, s. 4659-4668Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two mononuclear ruthenium complexes [RuL(pic)(3)] (1) and [RuL(bpy)(pic)] (2) (H2L = 2,6-pyridinedicarboxylic acid, pic=4-picoline, bpy = 2,2'-bipyridine) have been synthesized and fully characterized. Both complexes could promote water oxidation chemically and photochemically. Compared with other known ruthenium-based water oxidation catalysts using [Ce(NH4)(2)(NO3)(6)] (Ce-IV) as the oxidant in solution at pH 1.0, complex 1 is one of the most active catalysts yet reported with an initial rate of 0.23 turnovers(-1). Under acidic conditions, the equatorial 4-picoline in complex 1 dissociates first. In addition, ligand exchange in 1 occurs when the Rum state is reached. Based on the above observations and MS measurements of the intermediates during water oxidation by 1 using Ce-IV as oxidant, [RuL(pic)(2)(H2O)](+) is proposed as the real water oxidation catalyst.

  • 82.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Xu, Yunhua
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Tong, Lianpeng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ce-IV- and Light-Driven Water Oxidation by [Ru(terpy)(pic)(3)](2+) Analogues: Catalytic and Mechanistic Studies2011Inngår i: CHEMSUSCHEM, ISSN 1864-5631, Vol. 4, nr 2, s. 238-244Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of mononuclear ruthenium polypyridyl complexes [Ru(Mebimpy)(pic)(3)](PF6)(2) (2; Mebimpy=2,6-bis(1-methylbenzimidazol-2-yl)pyridine; pic=4-picoline), Ru(bimpy)(pic)(3) (3; H(2)bimpy=2,6-bis(benzimidazol-2-yl)pyridine), trans-[Ru(terpy)-(pic)(2)Cl](PF6) (4; terpy=2,2';6',2 ''-terpyridine), and trans-[Ru(terpy)(pic)(2)(OH2)](ClO4)(2) (5) are synthesized and characterized as analogues of the known Ru complex, [Ru(terpy)(pic)(3)](PF6)(2) (1). The effect of the ligands on electronic and catalytic properties is studied and discussed. The negatively charged ligand, bimpy(2-), has a remarkable influence on the electrochemical events due to its strong electron-donating ability. The performance in light- and Ce-IV-driven (Ce-IV=Ce(NH4)(2)(NO3)(6)) water oxidation is successfully demonstrated. We propose that ligand exchange between pic and H2O occurs to form the real catalyst, a Ru-aqua complex. The synthesis and testing of trans[Ru(terpy)(pic)(2)(OH2)](ClO4)(2) (5) confirmed our proposal. In addition, complex 5 possesses the best catalytic activity among these five complexes.

  • 83.
    Duan, Lele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Xu, Yunhua
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Zhang, Pan
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Wang, Mei
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Visible Light-Driven Water Oxidation by a Molecular Ruthenium Catalyst in Homogeneous System2010Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 49, nr 1, s. 209-215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Discovery of an efficient catalyst bearing low overpotential toward water oxidation is a key step for light-driven water splitting into dioxygen and dihydrogen. A mononuclear ruthenium complex, Ru(II)L(pic)(2) (1) (H2L = 2,2'-bipyridine-6,6'-dicarboxylic acids pic = 4-picoline), was found capable of oxidizing water eletrochemically at a relatively low potential and promoting light-driven water oxidation using a three-component system composed of a photosensitizer, sacrificial electron acceptor, and complex 1. The detailed electrochemical properties of 1 were studied, and the onset potentials of the electrochemically catalytic curves in pH 7.0 and pH 1.0 solutions are 1.0 and 1.5 V, respectively. The low catalytic potential of 1 under neutral conditions allows the use of [Ru(bpy)(3)](2+) and even [Ru(dmbpy)(3)](2+) as a photosensitizer for photochemical water oxidation. Two different sacrificial electron acceptors, [Co(NH3)(5)Cl]Cl-2 and Na2S2O8, were used to generate the oxidized state of ruthenium tris(2,2'-bipyridyl) photosensitizers. In addition, a two-hour photolysis of I in a pH TO phosphate buffer did not lead to obvious degradation, indicating the good photostability of our catalyst. However, under conditions of light-driven water oxidation, the catalyst deactivates quickly. In both solution and the solid state under aerobic conditions, complex 1 gradually decomposed via oxidative degradation of its ligands, and two of the decomposed products, sp(3) C-H bond oxidized Ru complexes, were identified. The capability of oxidizing the sp(3) C-H bond implies the presence of a highly oxidizing Ru species, which might also cause the final degradation of the catalyst.

  • 84. Ekstrom, J.
    et al.
    Ott, S.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Akermark, B.
    Eriksson, L.
    Pentacarbonyl(diphenyl(N-propylamine)phosphine)diiron(mu-1,3-propanedithiolate)2005Inngår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 61, s. M852-M853Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The title compound, (μ-(SCH2)(2)CH2) Fe(CO)(3)Fe(CO)(2)P( C6H5)(2)NHCH2CH2CH3, has been prepared and characterized as a a model substance for a class of enzymes known as hydrogenases.

  • 85. Ekström, Jesper
    et al.
    Abrahamsson, Maria
    Olson, Carol
    Bergquist, Jonas
    Kaynak, Filiz B.
    Eriksson, Lars
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Becker, Hans-Christian
    Akermark, Bjoern
    Hammarstroem, Leif
    Ott, Sascha
    Bio-inspired, side-on attachment of a ruthenium photosensitizer to an iron hydrogenase active site model2006Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, nr 38, s. 4599-4606Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first ruthenium - diiron complex [(mu- pdt) Fe-2(CO)(5){PPh2(C(6)H(4)CCbpy)} Ru(bpy)(2)](2+) 1 (pdt = propyldithiolate, bpy = 2,2'-bipyridine) is described in which the photoactive ruthenium trisbipyridyl unit is linked to a model of the iron hydrogenase active site by a ligand directly attached to one of the iron centers. Electrochemical and photophysical studies show that the light-induced MLCT excited state of the title complex is localized towards the potential diiron acceptor unit. However, the relatively mild potential required for the reduction of the acetylenic bipyridine together with the easily oxidized diiron portion leads to a reductive quenching of the excited state, instead. This process results in a transiently oxidized diiron unit which may explain the surprisingly high light sensitivity of complex 1.

  • 86. Elawad, M.
    et al.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Mola, G. T.
    Yu, Z.
    Arbab, E. A. A.
    Enhanced performance of perovskite solar cells using p-type doped PFB:F4TCNQ composite as hole transport layer2019Inngår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 771, s. 25-32Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Conjugated polymers have been widely used as hole transport materials (HTM) in the preparation of mesoscopic perovskite solar cells (PSCs). In this work, we employed p-type doped conducting polymer known as poly(9,9-dioctylfluorene-co-bis-N,N-(-4-butyl phenyl)-bis-N,N-phenyl-1,4-phenylenediamine) (PFB) as a hole transport material (HTM) in perovskite based solar cell. The effect of dopant concentration on the optical and electrical properties of PEB was investigated to optimize the electrical properties of the material for the best function of the solar cell. The highest power conversion efficiency of mesoscopic perovskite solar cells (PSCs), fabricated in this investigation, was found to be 14.04% which is 57% higher than that of pristine PFB hole transport layer. The UV–Vis absorption and Raman spectroscopy measurements confirm the occurrence of oxidation in a p-type doped PFB hole transport layer. This is attributed to the transfer of electrons from the highest occupied molecular orbital (HOMO) of PEB to the lowest unoccupied molecular orbital (LUMO) of F4TCNQ. The solar cells produced using p-type doped PFB:F4TCNQ composite not only improves device performances but also shows superior long-term stability. The optical, morphological and electrical properties of the doped composite PFB: F4TCNQ and newly fabricated devices are presented and discussed in this paper.

  • 87. Ellis, Hanna
    et al.
    Eriksson, Susanna K.
    Feldt, Sandra M.
    Gabrielsson, Erik
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Lohse, Peter W.
    Lindblad, Rebecka
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Rensmo, Håkan
    Boschloo, Gerrit
    Hagfeldt, Anders
    Linker Unit Modification of Triphenylamine-Based Organic Dyes for Efficient Cobalt Mediated Dye-Sensitized Solar Cells2013Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, nr 41, s. 21029-21036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Linker unit modification of donor-linker-acceptor-based organic dyes was investigated with respect to the spectral and physicochemical properties of the dyes. The spectral response for a series of triphenylamine (TPA)-based organic dyes, called LEG1-4, was shifted into the red wavelength region, and the extinction coefficient of the dyes was increased by introducing different substituted dithiophene units on the pi-conjugated linker. The photovoltaic performance of dye-sensitized solar cells (DSCs) incorporating the different dyes in combination with cobalt-based electrolytes was found to be dependent on dye binding. The binding morphology of the dyes on the TiO2 was studied using photoelectron spectroscopy, which demonstrated that the introduction of alkyl chains and different substituents on the dithiophene linker unit resulted in a larger tilt angle of the dyes with respect to the normal of the TiO2-surface, and thereby a lower surface coverage. The good photovoltaic performance for cobalt electrolyte-based DSCs found here and by other groups using TPA-based organic dyes with a cyclopentadithiophene linker unit substituted with alkyl chains was mainly attributed to the extended spectral response of the dye, whereas the larger tilt angle of the dye with respect to the TiO2-surface resulted in less efficient packing of the dye molecules and enhanced recombination between electrons in TiO2 and Co(III) species in the electrolyte.

  • 88.
    Fan, Ke
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Chen, Hong
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ji, Yongfei
    Huang, Hui
    Claesson, Per Martin
    Daniel, Quentin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Philippe, Bertrand
    Rensmo, Hakan
    Li, Fusheng
    Luo, Yi
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Nickel-vanadium monolayer double hydroxide for efficient electrochemical water oxidation2016Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 7, artikkel-id 11981Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial requirements remains a challenge. Herein, we report a monolayer of nickel-vanadium-layered double hydroxide that shows a current density of 27 mA cm(-2) (57 mA cm(-2) after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel-iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel-vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting.

  • 89.
    Fan, Ke
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Li, Fusheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Wang, Lei
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Daniel, Quentin
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Gabrielsson, Erik
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi. Dalian University of Technology (DUT), China.
    Pt-free tandem molecular photoelectrochemical cells for water splitting driven by visible light2014Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, nr 46, s. 25234-25240Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photoelectrochemical (PEC) cells using molecular catalysts to split water into hydrogen and oxygen have been investigated intensively during the past years. However, the high-cost of Pt counter electrodes and instability of molecular PEC cells hinder the practical applications. We describe in this article a Pt-free tandem molecular PEC cell, for the first time, employing molecular ruthenium- and cobalt-catalysts with strong dipicolinic acid anchoring groups on the respective photoanode and photocathode for total water splitting. The Pt-free tandem molecular PEC cell showed an effective and steady photocurrent density of ca. 25 mu A cm(-2) for water splitting driven by visible light without external bias. This study indicates that tandem molecular PEC cells can provide great potential to the Pt-free devices for light driven total water splitting.

  • 90.
    Fan, Ke
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Li, Fusheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Wang, Lei
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Quentin, Daniel
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Chen, H.
    Gabrielsson, Erik
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sun, J.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology (DUT), Dalian, China.
    Immobilization of a Molecular Ruthenium Catalyst on Hematite Nanorod Arrays for Water Oxidation with Stable Photocurrent2015Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, nr 19, s. 3242-3247Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photoelectrochemical (PEC) cells for light-driven water splitting are prepared using hematite nanorod arrays on conductive glass as the photoanode. These devices improve the photocurrent of the hematite-based photoanode for water splitting, owing to fewer surface traps and decreased electron recombination resulting from the one-dimensional structure. By employing a molecular ruthenium co-catalyst, which contains a strong 2,6-pyridine-dicarboxylic acid anchoring group at the hematite photoanode, the photocurrent of the PEC cell is enhanced with high stability for over 10000s in a 1M KOH solution. This approach can pave a route for combining one-dimensional nanomaterials and molecular catalysts to split water with high efficiency and stability.

  • 91. Fan, Ke
    et al.
    Zou, Haiyuan
    Lu, Yue
    Beijing Univ Technol, Inst Microstruct & Properties Adv Mat, Beijing 100124, Peoples R China..
    Chen, Hong
    Li, Fusheng
    Liu, Jinxuan
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Tong, Lianpeng
    Toney, Michael F.
    Sui, Manling
    Yu, Jiaguo
    Direct Observation of Structural Evolution of Metal Chalcogenide in Electrocatalytic Water Oxidation2018Inngår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, nr 12, s. 12369-12379Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As one of the most remarkable oxygen evolution reaction (OER) electrocatalysts, metal chalcogenides have been intensively reported during the past few decades because of their high OER activities. It has been reported that electron-chemical conversion of metal OER chalcogenides into oxides/hydroxides would take place after the OER. However, the transition mechanism of such unstable structures, as well as the real active sites and catalytic activity during the OER for these electrocatalysts, has not been understood yet; therefore a direct observation for the electrocatalytic water oxidation process, especially at nano or even angstrom scale, is urgently needed. In this research, by employing advanced Cs-corrected transmission electron microscopy (TEM), a step by step oxidational evolution of amorphous electrocatalyst CoSx into crystallized CoOOH in the OER has been in situ captured: irreversible conversion of CoSx to crystallized CoOOH is initiated on the surface of the electrocatalysts with a morphology change via Co(OH)(2) intermediate during the OER measurement, where CoOOH is confirmed as the real active species. Besides, this transition process has also been confirmed by multiple applications of X-ray photoelectron spectroscopy (XPS), in situ Fourier-transform infrared spectroscopy (FTIR), and other ex situ technologies. Moreover, on the basis of this discovery, a high-efficiency electrocatalyst of a nitrogen-doped graphene foam (NGF) coated by CoSx has been explored through a thorough structure transformation of CoOOH. We believe this in situ and in-depth observation of structural evolution in the OER measurement can provide insights into the fundamental understanding of the mechanism for the OER catalysts, thus enabling the more rational design of low-cost and high-efficient electrocatalysts for water splitting.

  • 92.
    Fan, Lizhou
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Zhang, Peili
    DUT, DUT KTH Joint Educ, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China.;DUT, Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Zhang, Biaobiao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Daniel, Quentin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Timmer, Brian
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Zhang, Fuguo
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi. DUT, DUT KTH Joint Educ, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China.;DUT, Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    3D Core-Shell NiFeCr Catalyst on a Cu Nanoarray for Water Oxidation: Synergy between Structural and Electronic Modulation2018Inngår i: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 3, nr 12, s. 2865-2874Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low cost transition metal-based electrocatalysts for water oxidation and understanding their structure-activity relationship are greatly desired for clean and sustainable chemical fuel production. Herein, a core-shell (CS) NiFeCr metal/metal hydroxide catalyst was fabricated on a 3D Cu nanoarray by a simple electrodeposition-activation method. A synergistic promotion effect between electronic structure modulation and nanostructure regulation was presented on a CS-NiFeCr oxygen evolution reaction (OER) catalyst: the 3D nanoarchitecture facilitates the mass transport process, the in situ formed interface metal/metal hydroxide heterojunction accelerates the electron transfer, and the electronic structure modulation by Cr incorporation improves the reaction kinetics. Benefiting from the synergy between structural and electronic modulation, the catalyst shows excellent activity toward water oxidation under alkaline conditions: overpotential of 200 mV at 10 mA/cm(2) current density and Tafel slope of 28 mV/dec. This work opens up a new window for understanding the structure-activity relationship of OER catalysts and encourages new strategies for development of more advanced OER catalysts.

  • 93.
    Fan, Ting
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Duan, Lele
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Huang, Ping
    Chen, Hong
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Daniel, Quentin
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ahlquist, Mårten S. G.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    The Ru-tpc Water Oxidation Catalyst and Beyond: Water Nucleophilic Attack Pathway versus Radical Coupling Pathway.2017Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, nr 4, s. 2956-2966Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many Ru water oxidation catalysts have been documented in the literature. However, only a few can catalyze the O-O bond formation via the radical coupling pathway, while most go through the water nucleophilic attack pathway. Understanding the electronic effect on the reaction pathway is of importance in design of active water oxidation catalysts. The Ru-bda (bda = 2,2'-bipyridine-6,6'-dicarboxylate) catalyst is one example that catalyzes the 0-0 bond formation via the radical coupling pathway. Herein, we manipulate the equatorial backbone ligand, change the doubly charged bda(2-) ligand to a singly charged tpc- (2,2':6',2 ''-terpyridine-6-carboxylate) ligand, and study the structure activity relationship. Surprisingly, kinetics measurements revealed that the resulting Ru-tpc catalyst catalyzes water oxidation via the water nucleophilic attack pathway, which is different from the Ru-bda catalyst. The O-O bond formation Gibbs free energy of activation (AGO) at T = 298.15 K was 20.2 +/- 1.7 kcal mol(-1). The electronic structures of a series of Ru-v=O species were studied by density function theory calculations, revealing that the spin density of O-Ru=O of Ru-v=O is largely dependent on the surrounding ligands. Seven coordination configuration significantly enhances the radical character of Ru-v=O.

  • 94. Feldt, Sandra M.
    et al.
    Gibson, Elizabeth A.
    Gabrielsson, Erik
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Boschloo, Gerrit
    Hagfeldt, Anders
    Design of Organic Dyes and Cobalt Polypyridine Redox Mediators for High-Efficiency Dye-Sensitized Solar Cells2010Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, nr 46, s. 16714-16724Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dye-sensitized solar cells (DSCs) with cobalt-based mediators with efficiencies surpassing the record for DSCs with iodide-free electrolytes were developed by selecting a suitable combination of a cobalt polypyridine complex and an organic sensitizer. The effect of the steric properties of two triphenylamine-based organic sensitizers and a series of cobalt polypyridine redox mediators on the overall device performance in DSCs as well as on transport and recombination processes in these devices was compared. The recombination and mass-transport limitations that, previously, have been found to limit the performance of these mediators were avoided by matching the properties of the dye and the cobalt redox mediator. Organic dyes with higher extinction coefficients than the standard ruthenium sensitizers were employed in DSCs in combination with outer-sphere redox mediators, enabling thinner TiO2 films to be used. Recombination was reduced further by introducing insulating butoxyl chains on the dye rather than on the cobalt redox mediator, enabling redox couples with higher diffusion coefficients and more suitable redox potential to be used, simultaneously improving the photocurrent and photovoltage of the device. Optimization of DSCs sensitized with a triphenylamine-based organic dye in combination with tris(2,2'-bipyridyl)cobalt(II/III) yielded solar cells with overall conversion efficiencies of 6.7% and open-circuit potentials of more than 0.9 V under 1000 W m(-2) AM1.5 G illumination. Excellent performance was also found under low light intensity indoor conditions.

  • 95. Fredin, Kristofer
    et al.
    Anderson, Kenrick F.
    Duffy, Noel W.
    Wilson, Gregory J.
    Fell, Christopher J.
    Hagberg, Daniel P.
    KTH, Skolan för kemivetenskap (CHE).
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Bach, Udo
    Lindquist, Sten-Eric
    Effect on Cell Efficiency following Thermal Degradation of Dye-Sensitized Mesoporous Electrodes Using N719 and D5 Sensitizers2009Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 113, nr 43, s. 18902-18906Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work examines the comparative durability of two common dyes at temperatures that may be experienced during fabrication of dye-sensitized solar cells (DSCs) such as through the application of thermoplastics for encapsulation or the use of a molten solid-state hole conductor. Dye-sensitized electrodes were heated in an atmosphere of air or nitrogen and thereafter used as working electrodes in DSCs. Electrodes sensitized with N719 appeared more sensitive to thermal degradation than electrodes sensitized with D5, although absorbance measurements suggest similar first-order degradation rates for the two dyes. Intensity modulated photovoltage spectroscopy and intensity modulated photocurrent spectroscopy were used to measure the effect of heating on electron lifetime and transport. It was found that the electron diffusion length may.. be as low as 10% for heated samples, compared to that of the unheated counterpart, and therefore, we assess recombination as an additional efficiency limiting process in our experiments.

  • 96. Fredin, Kristofer
    et al.
    Johansson, Erik M. J.
    Hahlin, Maria
    Schölin, Rebecka
    Plogmaker, Stefan
    Gabrielsson, Erik
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Rensmo, Håkan
    Solid state dye-sensitized solar cells prepared by infiltrating a molten hole conductor into a mesoporous film at a temperature below 150 degrees C2011Inngår i: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 161, nr 21-22, s. 2280-2283Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Infiltration of a molten hole conductor in a mesoporous film at an elevated temperature exhibits good wetting performance and the procedure is therefore suitable as part of the preparation method for solid state dye-sensitized solar cells. Herein, we present a system prepared by infiltrating 4-(diethylamino)benzaldehyde-1,1)-diphenyl-hydrazone in its molten form at a temperature below 150 degrees C. The system displays a maximum photon-to-current conversion efficiency of about 35%, a value corresponding to an increase of about 5 times in comparison with a previously published system prepared by infiltrating a molten hole-conductor at a temperature exceeding 250 degrees C. By means of comparing charge transport and recombination with the results measured for a liquid analogue, we conclude that whereas the transport rates are similar, recombination is significantly more rapid in the solid-state device.

  • 97.
    Freitag, Marina
    et al.
    Uppsala Univ, Dept Chem Angstrom Lab, Sweden..
    Quentin, Daniel
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Pazoki, Meysam
    Uppsala Univ, Dept Chem Angstrom Lab, Sweden..
    Sveinbjornsson, Kari
    Uppsala Univ, Dept Chem Angstrom Lab, Sweden..
    Zhang, Jinbao
    Uppsala Univ, Dept Chem Angstrom Lab, Sweden..
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology (DUT), Dalian, China.
    Hagfeldt, Anders
    Uppsala Univ, Dept Chem Angstrom Lab, Sweden..
    Boschloo, Gerrit
    Uppsala Univ, Dept Chem Angstrom Lab, Sweden..
    High-efficiency dye-sensitized solar cells with molecular copper phenanthroline as solid hole conductor2015Inngår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 8, nr 9, s. 2634-2637Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Copper phenanthroline complexes in the solid phase can act as efficient molecular hole transporting material (HTM) for hybrid solar cells. We prepared solid-state dye-sensitized solar cells with the organic dye LEG4 and bis(2,9-dimethyl-1,10-phenanthroline)copper(I/II) (Cu(dmp)(2)) and achieved power conversion efficiencies of more than 8% under 1000 W m(-2) AM1.5G illumination, with open-circuit potentials of more than 1.0 V. The successful application of a copper-complex based HTM paves the way for low-cost and efficient hybrid solar cells, as well as for other opto-electronic devices.

  • 98.
    Gabrielsson, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Ellis, Hanna
    Feldt, Sandra
    Tian, Haining
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Boschloo, Gerrit
    Hagfeldt, Anders
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Convergent/Divergent Synthesis of a Linker-Varied Series of Dyes for Dye-Sensitized Solar Cells Based on the D35 Donor2013Inngår i: Advanced Energy Materials, ISSN 1614-6832, Vol. 3, nr 12, s. 1647-1656Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of four new dyes, based on the D35 type donor moiety with varied linker units, is synthesized using a facile convergent/divergent method, enabled by an improved synthesis of the D35 donor. The dyes are evaluated in dye sensitized solar cells with Co(II/III)(bpy)(3)-based electrolytes. By extending the linker fragment, higher photocurrents and solar energy conversion efficiencies are achieved. It is also found that the linker unit plays a crucial role in maintaining a high open-circuit photovoltage. Based on the photovoltaic performance it is concluded that the hexylthiophene unit is the most suitable for this purpose, as it allows further enhancement of the already high open-circuit voltage of D35 to 0.92 V. The best dye in this series reaches an efficiency of 6.8%.

  • 99.
    Gabrielsson, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Hao, Yan
    Lohse, Peter William
    Johansson, Erik Martin Jesper
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Hagfeldt, Anders
    Boschloo, Gerrit
    Control of Interfacial Charge Transfer in Organic Dye-SensitizedSolar Cells Based on Cobalt ElectrolytesManuskript (preprint) (Annet vitenskapelig)
  • 100.
    Gabrielsson, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Tian, Haining
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Eriksson, Susanna K.
    Gao, Jiajia
    Chen, Hong
    Li, Fusheng
    Oscarsson, Johan
    Sun, Juliang
    Resmo, Håkan
    Kloo, lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Hagfeldt, Anders
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Dipicolinic Acid: A Strong Anchoring Group with Tunable Redoxand Spectral Behavior for Stable Dye-Sensitized Solar CellsManuskript (preprint) (Annet vitenskapelig)
1234567 51 - 100 of 490
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  • text
  • asciidoc
  • rtf