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  • 1.
    Daniel, Quentin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Anabre, Ram B.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Zhang, Biaobiao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Philippe, Bertrand
    Chen, Hong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Fan, Ke
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ahmadi, Sareh
    Rensmo, Hakan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology (DUT), China.
    Re-Investigation of Cobalt Porphyrin for Electrochemical Water Oxidation on FTO Surface: Formation of CoOx as Active Species2017In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, no 2, p. 1143-1149Article in journal (Refereed)
    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.

  • 2.
    Daniel, Quentin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Timmer, Brian J. J.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Chen, Hong
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Luo, Xiaodan
    Peking Univ, Coll Chem & Mol Engn, Beijing 100871, Peoples R China..
    Ambre, Ram
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Wang, Ying
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Zhang, Biaobiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Zhang, Peili
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Wang, Lei
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Sun, Junliang
    Peking Univ, Coll Chem & Mol Engn, Beijing 100871, Peoples R China..
    Ahlquist, Mårten S. G.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Water Oxidation Initiated by In Situ Dimerization of the Molecular Ru(pdc) Catalyst2018In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, no 5, p. 4375-4382Article in journal (Refereed)
    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.

  • 3.
    Daniel, Quentin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Huang, Ping
    Fan, Ting
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Wang, Ying
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rinkevicius, Zilvinas
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ahlquist, Mårten S. G.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Mamedov, Fikret
    Styring, Stenbjörn
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rearranging from 6-to 7-coordination initiates the catalytic activity: An EPR study on a Ru-bda water oxidation catalyst2017In: Coordination chemistry reviews, ISSN 0010-8545, E-ISSN 1873-3840, Vol. 346, p. 206-215Article in journal (Refereed)
    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.

  • 4.
    Daniel, Quentin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. 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 oxidation2016In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, no 37, p. 14689-14696Article in journal (Refereed)
    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.

  • 5.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Fei
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. 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 Ligands2015In: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 48, no 7, p. 2084-2096Article, review/survey (Refereed)
    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.

  • 6.
    Fan, Ke
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Daniel, Quentin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Gabrielsson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Dalian University of Technology (DUT), China.
    Pt-free tandem molecular photoelectrochemical cells for water splitting driven by visible light2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 46, p. 25234-25240Article in journal (Refereed)
    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.

  • 7.
    Fan, Ke
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Quentin, Daniel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chen, H.
    Gabrielsson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, J.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. 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 Photocurrent2015In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 19, p. 3242-3247Article in journal (Refereed)
    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.

  • 8.
    Gabrielsson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Tian, Haining
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. Uppsala University, Sweden.
    Eriksson, Susanna K.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Chen, Hong
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Oscarsson, Johan
    Sun, Junliang
    Rensmo, Håkan
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Hagfeldt, Anders
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. Dalian University of Technology (DUT), China.
    Dipicolinic acid: a strong anchoring group with tunable redox and spectral behavior for stable dye-sensitized solar cells2015In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 18, p. 3858-3861Article in journal (Refereed)
    Abstract [en]

    Dipicolinic acidwas investigated as a new anchoring group for DSSCs. A pilot dye (PD2) bearing this new anchoring group was found to adsorb significantly stronger to TiO2 than its cyanoacrylic acid analogue. The electrolyte composition was found to have a strong effect on the photoelectrochemical properties of the adsorbed dye in the device, allowing the dye LUMO energy to be tuned by 0.5 eV. Using a pyridine-free electrolyte, panchromatic absorption of the dye on TiO2 extending to 900 nm has been achieved. Solar cells using PD2 and a Co(bpy)(3) based electrolyte showed unique stability under simulated sunlight and elevated temperatures.

  • 9.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Design of Water Splitting Devices via Molecular Engineering2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Converting solar energyto fuels such as hydrogen by the reaction of water splitting is a promising solution for the future sustainable energy systems. The theme of this thesis is to design water splitting devices via molecular engineering; it concerns the studies of both electrochemical-driven and photo-electrochemical driven molecular functional devices for water splitting.

    The first chapter presents a general introduction about Solar Fuel Conversion. It concerns molecular water splitting catalysts, light harvesting materials and fabrication methods of water splitting devices.

    The second chapter describes an electrode by immobilizing a molecular water oxidation catalyston carbon nanotubes through the hydrophobic interaction. This fabrication method is corresponding to the question: “How to employ catalysts in functional devices without affecting their performances?”

    In the third chapter, molecular water oxidation catalysts were successfully immobilized on glassy carbon electrode surface via electrochemical polymerization method. The O-O bond formation pathways of catalysts on electrode surfaces were studied. This kinetic studyis corresponding to the question: “How to get kinetic information of RDS whena catalyst is immobilized on the electrode surface?”

    Chapter four explores molecular water oxidation catalysts immobilized on dye-sensitized TiO2 electrodeand Fe2O3 semiconductor electrode via different fabrication methods. The reasons of photocurrent decay are discussed and two potential solutions are provided. These studies are corresponding to the question: “How to improvethe stability of photo-electrodes?”

    Finally, in the last chapter, two novel Pt-free Z-schemed molecular photo-electrochemical cells with both photoactive cathode and photoactive anode for visible light driven water splitting driven were demonstrated. These studies are corresponding to the question: “How to utilizethe concept of Z-schemein photosynthesis to fabricate Pt-free molecular based PEC cells?

  • 10.
    Li, Fusheng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fan, Ke
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Daniel, Quentin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chen, Hong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology, China.
    Control the O-O bond formation pathways by immobilizing molecular catalysts on glassy carbon via electrochemical polymerizationManuscript (preprint) (Other academic)
    Abstract [en]

    Molecular water oxidation catalysts Ru-bda (1) and Ru-pda (2) are electrochemically polymerized on glassy carbon (GC) electrodes. Reaction orders and kinetic isotope effects (KIE) of the corresponding electrodes are studied. Results indicate that poly-1@GC goes through a radical coupling pathway. By adding poly-styrene (PSt) as a “blocking unit” in the poly-1, the radical coupling process of Ru-bda is blocked, and poly-1+PSt@GC catalyzes water oxidation through the water nucleophilic attack pathway. In comparison, catalyst 2, which oxidizes water via water nucleophilic attack path in homogeneous systems, goes through a radical coupling pathway as well when 2 is polymerized on glassy carbon (poly-2@GC).

  • 11.
    Li, Fusheng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fan, Ke
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Daniel, Quentin
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. State Key Laboratory of Fine Chemicals, Research Center on Molecular Devices, Dalian University of Technology (DUT), Dalian, China .
    Immobilizing Ru(bda) Catalyst on a Photoanode via Electrochemical Polymerization for Light-Driven Water Splitting2015In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 5, no 6, p. 3786-3790Article in journal (Refereed)
    Abstract [en]

    The molecular water oxidation catalyst 1 was electrochemically polymerized on a dye-sensitized TiO2 electrode and an Fe2O3 nanorod electrode. High photocurrent densities of ca. 1.4 mA cm(-2) for poly-1+RuP@TiO2 and ca. 0.4 mA cm(-2) for poly-1@Fe2O3 were achieved under pH-neutral conditions. A kinetic isotope effect (KIE) study on poly-1+RuP@TiO2 shows that poly-1 catalyzes water oxidation on the surface of TiO2 via a radical coupling mechanism.

  • 12.
    Li, Fusheng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fan, Ke
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Xu, Bo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Gabrielsson, Erik
    Daniel, Quentin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Lin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology (DUT), Dalian, China.
    Organic Dye-Sensitized Tandem Photoelectrochemical Cell for Light Driven Total Water Splitting2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 28, p. 9153-9159Article in journal (Refereed)
    Abstract [en]

    Light driven water splitting was achieved by a tandem dye-sensitized photoelectrochemical cell with two photoactive electrodes. The photoanode is constituted by an organic dye L0 as photosensitizer and a molecular complex Ru1 as water oxidation catalyst on meso-porous TiO2, while the photocathode is constructed with an organic dye P1 as photoabsorber and a molecular complex Col as hydrogen generation catalyst on nanostructured NiO. By combining the photocathode and the photoanode, this tandem DS-PEC cell can split water by visible light under neutral pH conditions without applying any bias.

  • 13.
    Li, Fusheng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Li, Lin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tong, Lianpeng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Daniel, Quentin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Immobilization of a molecular catalyst on carbon nanotubes for highly efficient electro-catalytic water oxidation2014In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 50, no 90, p. 13948-13951Article in journal (Refereed)
    Abstract [en]

    Electrochemically driven water oxidation has been performed using a molecular water oxidation catalyst immobilized on hybrid carbon nanotubes and nano-material electrodes. A high turnover frequency (TOF) of 7.6 s(-1) together with a high catalytic current density of 2.2 mA cm(-2) was successfully obtained at an overpotential of 480 mV after 1 h of bulk electrolysis.

  • 14.
    Wang, Lei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fan, Ke
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Daniel, Quentin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Philippe, B.
    Rensmo, H.
    Chen, H.
    Sun, J.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Electrochemical driven water oxidation by molecular catalysts in situ polymerized on the surface of graphite carbon electrode2015In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 37, p. 7883-7886Article in journal (Refereed)
    Abstract [en]

    A simple strategy to immobilize highly efficient ruthenium based molecular water-oxidation catalysts on the basal-plane pyrolytic graphite electrode (BPG) by polymerization has been demonstrated. The electrode 1@BPG has obtained a high initial turnover frequency (TOF) of 10.47 s-1 at ∼700 mV overpotential, and a high turnover number (TON) up to 31600 in 1 h electrolysis.

  • 15. Wang, Lei
    et al.
    Mirmohades, Mohammad
    Brown, Allison
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Quentin, Daniel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lomoth, Reiner
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China.
    Hammarstrom, Leif
    Sensitizer-Catalyst Assemblies for Water Oxidation2015In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 54, no 6, p. 2742-2751Article in journal (Refereed)
    Abstract [en]

    Two molecular assemblies with one Ru(II)-polypyridine photosensitizer covalently linked to one Ru(II)(bda)L2 catalyst (1) (bda = 2,2'-bipyridine-6,6'-dicarboxylate) and two photosensitizers covalently linked to one catalyst (2) have been prepared using a simple C-C bond as the linkage. In the presence of sodium persulfate as a sacrificial electron acceptor, both of them show high activity for catalytic water oxidation driven by visible light, with a turnover number up to 200 for 2. The linked photocatalysts show a lower initial yield for light driven oxygen evolution but a much better photostability compared to the three component system with separate sensitizer, catalyst and acceptor, leading to a much greater turnover number. Photocatalytic experiments and time-resolved spectroscopy were carried out to probe the mechanism of this catalysis. The linked catalyst in its Ru(II) state rapidly quenches the sensitizer, predominantly by energy transfer. However, a higher stability under photocatalytic condition is shown for the linked sensitizer compared to the three component system, which is attributed to kinetic stabilization by rapid photosensitizer regeneration. Strategies for employment of the sensitizer-catalyst molecules in more efficient photocatalytic systems are discussed.

  • 16. Yamamoto, Masanori
    et al.
    Nishizawa, Yusuke
    Chabera, Pavel
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Pascher, Torbjörn
    Sundström, Villy
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Imahori, Hiroshi
    Visible light-driven water oxidation with a subporphyrin sensitizer and a water oxidation catalyst2016In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 52, no 94, p. 13702-13705Article in journal (Refereed)
    Abstract [en]

    A new subporphyrin was synthesized for use as a molecular sensitizer in electrochemical and dye-sensitized photoelectrochemical water oxidation. A photoelectrochemical cell with a TiO2 electrode modified with the sensitizer and a molecular water oxidation catalyst generated higher photocurrent than reference cells that have electrodes modified with either the photosensitizer or the catalyst under visible light (lambda > 500 nm) illumination. Oxygen evolution was confirmed after photolysis by GC and GC-MS analyses using isotope-labeling experiments. The large molar extinction coefficients of the ring-contracted porphyrin in the visible region enabled kinetic analysis by time-resolved transient absorption spectroscopy, which also supported the photocatalytic activity.

  • 17. Yamamoto, Masanori
    et al.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fukushima, Takashi
    Tanaka, Koji
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Imahori, Hiroshi
    Visible light-driven water oxidation using a covalently-linked molecular catalyst-sensitizer dyad assembled on a TiO2 electrode2016In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 7, no 2, p. 1430-1439Article in journal (Refereed)
    Abstract [en]

    The combination of porphyrin as a sensitizer and a ruthenium complex as a water oxidation catalyst (WOC) is promising to exploit highly efficient molecular artificial photosynthetic systems. A covalently-linked ruthenium-based WOC-zinc porphyrin (ZnP) sensitizer dyad was assembled on a TiO2 electrode for visible-light driven water oxidation. The water oxidation activity was found to be improved in comparison to the reference systems with the simple combination of the individual WOC and ZnP as well as with ZnP solely, demonstrating the advantage of the covalent linking approach over the non-covalent one. More importantly, via vectorial multi-step electron transfer triggered by visible light, the dye-sensitized photoelectrochemical cell (DSPEC) achieved a broader PEC response in the visible region than DSPECs with conventional ruthenium-based sensitizers. Initial incident photon-to-current efficiencies of 18% at 424 nm and 6.4% at 564 nm were attained under monochromatic illumination and an external bias of -0.2 V vs. NHE. Fast electron transfer from the WOC to the photogenerated radical cation of the sensitizer through the covalent linkage may suppress undesirable charge recombination, realizing the moderate performance of water oxidation. X-ray photoelectron spectroscopic analysis of the photoanodes before and after the DSPEC operation suggested that most of the ruthenium species exist at higher oxidation states, implying that the insufficient oxidation potential of the ZnP moiety for further oxidizing the intermediate ruthenium species at the photoanode is at least the bottleneck of the system.

  • 18.
    Zhang, Peili
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Chen, Hong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Wang, Mei
    Yang, Yong
    Jiang, Jian
    Zhang, Biaobiao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Daniel, Quentin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116023 Dalian, China .
    Gas-templating of hierarchically structured Ni-Co-P for efficient electrocatalytic hydrogen evolution2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 16, p. 7564-7570Article in journal (Refereed)
    Abstract [en]

    One of the grand challenges for developing scalable and sustainable hydrogen producing systems is the lack of efficient and robust earth-abundant element based catalysts for the hydrogen evolution reaction (HER). Herein, a hierarchically structured Ni-Co-P film was fabricated via a gas templating electro-deposition method. This film exhibits remarkably high catalytic performance for the HER in 1 M KOH with respective current densities of -10 and -500 mA cm(-2) at the overpotentials of -30 and -185 mV with a Tafel slope of 41 mV dec(-1). A controlled potential electrolysis experiment demonstrates that the as-prepared Ni-Co-P film is an efficient and robust catalyst with a faradaic efficiency close to 100%. Systematic characterization suggests that the unique hierarchical structure and the mutual participation of nano-sized Ni/Co based components are responsible for the high HER catalytic activity.

1 - 18 of 18
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