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Publications (10 of 10) Show all publications
Liu, T., Zhang, B. & Sun, L. (2019). Iron-Based Molecular Water Oxidation Catalysts: Abundant, Cheap, and Promising. Chemistry - An Asian Journal, 14(1), 31-43
Open this publication in new window or tab >>Iron-Based Molecular Water Oxidation Catalysts: Abundant, Cheap, and Promising
2019 (English)In: Chemistry - An Asian Journal, ISSN 1861-4728, E-ISSN 1861-471X, Vol. 14, no 1, p. 31-43Article, review/survey (Refereed) Published
Abstract [en]

An efficient and robust water oxidation catalyst based on abundant and cheap materials is the key to converting solar energy into fuels through artificial photosynthesis for the future of humans. The development of molecular water oxidation catalysts (MWOCs) is a smart way to achieve promising catalytic activity, thanks to the clear structures and catalytic mechanisms of molecular catalysts. Efficient MWOCs based on noble-metal complexes, for example, ruthenium and iridium, have been well developed over the last 30 years; however, the development of earth-abundant metal-based MWOCs is very limited and still challenging. Herein, the promising prospect of iron-based MWOCs is highlighted, with a comprehensive summary of previously reported studies and future research focus in this area.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
artificial photosynthesis, electrochemistry, iron, molecular catalysts, oxidation, water splitting
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-241314 (URN)10.1002/asia.201801253 (DOI)000454953700003 ()30362258 (PubMedID)2-s2.0-85057257052 (Scopus ID)
Note

QC 20190125

Available from: 2019-01-25 Created: 2019-01-25 Last updated: 2019-01-25Bibliographically approved
Fan, L., Zhang, P., Zhang, B., Daniel, Q., Timmer, B., Zhang, F. & Sun, L. (2018). 3D Core-Shell NiFeCr Catalyst on a Cu Nanoarray for Water Oxidation: Synergy between Structural and Electronic Modulation. ACS ENERGY LETTERS, 3(12), 2865-2874
Open this publication in new window or tab >>3D Core-Shell NiFeCr Catalyst on a Cu Nanoarray for Water Oxidation: Synergy between Structural and Electronic Modulation
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2018 (English)In: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 3, no 12, p. 2865-2874Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-241005 (URN)10.1021/acsenergylett.8b01897 (DOI)000453805100003 ()2-s2.0-85056263175 (Scopus ID)
Note

QC 20190109

Available from: 2019-01-09 Created: 2019-01-09 Last updated: 2019-01-09Bibliographically approved
Zhang, P., Li, L., Nordlund, D., Chen, H., Fan, L., Zhang, B., . . . Sun, L. (2018). Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation. Nature Communications, 9(1), Article ID 381.
Open this publication in new window or tab >>Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation
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2018 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, no 1, article id 381Article in journal (Refereed) Published
Abstract [en]

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm-2. The core-shell NiFeCu electrode exhibits pH-dependent oxygen evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-222290 (URN)10.1038/s41467-017-02429-9 (DOI)2-s2.0-85041107994 (Scopus ID)
Note

QC 20180206

Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-02-06Bibliographically approved
Wang, L., Zhang, J., Liu, P., Xu, B., Zhang, B., Chen, H., . . . Sun, L. (2018). Design and synthesis of dopant-free organic hole-transport materials for perovskite solar cells. Chemical Communications, 54(69)
Open this publication in new window or tab >>Design and synthesis of dopant-free organic hole-transport materials for perovskite solar cells
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2018 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 69Article in journal (Refereed) Published
Abstract [en]

Two novel dopant-free hole-transport materials (HTMs) with spiro[dibenzo[c,h]xanthene-7,9-fluorene] (SDBXF) skeletons were prepared via facile synthesis routes. A power conversion efficiency of 15.9% in perovskite solar cells is attained by using one HTM without dopants, which is much higher than undoped Spiro-OMeTAD-based devices (10.8%). The crystal structures of both new HTMs were systematically investigated to reveal the reasons behind such differences in performance and to indicate the design principles of more advanced HTMs.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:kth:diva-234569 (URN)10.1039/c8cc04026e (DOI)000442605100002 ()30043013 (PubMedID)2-s2.0-85052539543 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20180917

Available from: 2018-09-17 Created: 2018-09-17 Last updated: 2018-10-19Bibliographically approved
Daniel, Q., Duan, L., Timmer, B. J. J., Chen, H., Luo, X., Ambre, R., . . . Sun, L. (2018). Water Oxidation Initiated by In Situ Dimerization of the Molecular Ru(pdc) Catalyst. ACS Catalysis, 8(5), 4375-4382
Open this publication in new window or tab >>Water Oxidation Initiated by In Situ Dimerization of the Molecular Ru(pdc) Catalyst
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2018 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, no 5, p. 4375-4382Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
Keywords
solar fuels, water oxidation, electrochemistry, ruthenium dimer, mechanism of O-O bond formation
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-231630 (URN)10.1021/acscatal.7b03768 (DOI)000431727300070 ()2-s2.0-85046695744 (Scopus ID)
Note

QC 20180702

Available from: 2018-07-02 Created: 2018-07-02 Last updated: 2018-07-02Bibliographically approved
Zhang, B. & Sun, L. (2018). Why nature chose the Mn4CaO5 cluster as water-splitting catalyst in photosystem II: a new hypothesis for the mechanism of O-O bond formation. Dalton Transactions, 47(41), 14381-14387
Open this publication in new window or tab >>Why nature chose the Mn4CaO5 cluster as water-splitting catalyst in photosystem II: a new hypothesis for the mechanism of O-O bond formation
2018 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 47, no 41, p. 14381-14387Article, review/survey (Refereed) Published
Abstract [en]

Resolving the questions, namely, the selection of Mn by nature to build the oxygen-evolving complex (OEC) and the presence of a cubic Mn3CaO4 structure in OEC coupled with an additional dangling Mn (Mn4) via mu-O atom are not only important to uncover the secret of water oxidation in nature, but also essential to achieve a blueprint for developing advanced water-oxidation catalysts for artificial photosynthesis. Based on the important experimental results reported so far in the literature and on our own findings, we propose a new hypothesis for the water oxidation mechanism in OEC. In this new hypothesis, we propose for the first time, a complete catalytic cycle involving a charge-rearrangement-induced Mn-VII-dioxo species on the dangling Mn4 during the S-3 -> S-4 transition. Moreover, the O-O bond is formed within this Mn-VII-dioxo site, which is totally different from that discussed in other existing proposals.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-241340 (URN)10.1039/c8dt01931b (DOI)000454842000001 ()30129959 (PubMedID)2-s2.0-85055182383 (Scopus ID)
Note

QC 20190121

Available from: 2019-01-21 Created: 2019-01-21 Last updated: 2019-01-21Bibliographically approved
Zhang, B., Li, Y., Valvo, M., Fan, L., Daniel, Q., Zhang, P., . . . Sun, L. (2017). Electrocatalytic Water Oxidation Promoted by 3 D Nanoarchitectured Turbostratic Δ-MnOx on Carbon Nanotubes. ChemSusChem, 10(22), 4472-4478
Open this publication in new window or tab >>Electrocatalytic Water Oxidation Promoted by 3 D Nanoarchitectured Turbostratic Δ-MnOx on Carbon Nanotubes
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2017 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 22, p. 4472-4478Article in journal (Refereed) Published
Abstract [en]

The development of manganese-based water oxidation electrocatalysts is desirable for the production of solar fuels, as manganese is earth-abundant, inexpensive, non-toxic, and has been employed by the Photosystem II in nature for a billion years. Herein, we directly constructed a 3 D nanoarchitectured turbostratic δ-MnOx on carbon nanotube-modified nickel foam (MnOx/CNT/NF) by electrodeposition and a subsequent annealing process. The MnOx/CNT/NF electrode gives a benchmark catalytic current density (10 mA cm−2) at an overpotential (η) of 270 mV under alkaline conditions. A steady current density of 19 mA cm−2 is obtained during electrolysis at 1.53 V for 1.0 h. To the best of our knowledge, this work represents the most efficient manganese-oxide-based water oxidation electrode and demonstrates that manganese oxides, as a structural and functional model of oxygen-evolving complex (OEC) in Photosystem II, can also become comparable to those of most Ni- and Co-based catalysts.

Place, publisher, year, edition, pages
Wiley-VCH Verlag, 2017
Keywords
artificial photosynthesis, electrochemistry, manganese, turbostratic manganese oxide, water oxidation, Carbon, Carbon nanotubes, Electrocatalysts, Electrodes, Foams, Nanotubes, Nickel, Oxidation, Oxides, Yarn, Alkaline conditions, Annealing process, Catalytic current, Co-based catalysts, Oxygen-evolving complexes, Turbostratic, Manganese oxide, carbon nanotube, manganese derivative, oxide, water, catalysis, chemistry, electrochemical analysis, electrode, molecular mimicry, oxidation reduction reaction, photosystem II, procedures, solar energy, Electrochemical Techniques, Manganese Compounds, Nanotubes, Carbon, Oxidation-Reduction, Photosystem II Protein Complex
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-227139 (URN)10.1002/cssc.201700824 (DOI)000416158500023 ()28675680 (PubMedID)2-s2.0-85035013364 (Scopus ID)
Note

QC 20180503

Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2019-02-07Bibliographically approved
Zhang, P., Chen, H., Wang, M., Yang, Y., Jiang, J., Zhang, B., . . . Sun, L. (2017). Gas-templating of hierarchically structured Ni-Co-P for efficient electrocatalytic hydrogen evolution. Journal of Materials Chemistry A, 5(16), 7564-7570
Open this publication in new window or tab >>Gas-templating of hierarchically structured Ni-Co-P for efficient electrocatalytic hydrogen evolution
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2017 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 16, p. 7564-7570Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-206680 (URN)10.1039/c7ta01716b (DOI)000399390300036 ()2-s2.0-85017596277 (Scopus ID)
Note

QC 20170510

Available from: 2017-05-10 Created: 2017-05-10 Last updated: 2017-05-10Bibliographically approved
Zhang, W., Liu, P., Sadollahkhani, A., Li, Y., Zhang, B., Zhang, F., . . . Kloo, L. (2017). Investigation of Triphenylamine (TPA)-Based Metal Complexes and Their Application in Perovskite Solar Cells. ACS OMEGA, 2(12), 9231-9240
Open this publication in new window or tab >>Investigation of Triphenylamine (TPA)-Based Metal Complexes and Their Application in Perovskite Solar Cells
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2017 (English)In: ACS OMEGA, ISSN 2470-1343, Vol. 2, no 12, p. 9231-9240Article in journal (Refereed) Published
Abstract [en]

Triphenylamine-based metal complexes were designed and synthesized via coordination to Ni(II), Cu(II), and Zn(II) using their respective acetate salts as the starting materials. The resulting metal complexes exhibit more negative energy levels (vs vacuum) as compared to 2,2', 7,7'-tetrakis(N, N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD), high hole extraction efficiency, but low hole mobilities and conductivities. Application of dopants typically used for Spiro-OMeTAD was not successful, indicating a more complicated mechanism of partial oxidation besides the redox potential. However, utilization as hole-transport material was successful, giving a highest efficiency of 11.1% under AM 1.5G solar illumination.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-221019 (URN)10.1021/acsomega.7b01434 (DOI)000418744400078 ()2-s2.0-85040066582 (Scopus ID)
Funder
Swedish Energy AgencySwedish Research CouncilKnut and Alice Wallenberg Foundation
Note

QC 20180112

Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2018-01-15Bibliographically approved
Daniel, Q., Anabre, R. B., Zhang, B., Philippe, B., Chen, H., Li, F., . . . Sun, L. (2017). Re-Investigation of Cobalt Porphyrin for Electrochemical Water Oxidation on FTO Surface: Formation of CoOx as Active Species. ACS Catalysis, 7(2), 1143-1149
Open this publication in new window or tab >>Re-Investigation of Cobalt Porphyrin for Electrochemical Water Oxidation on FTO Surface: Formation of CoOx as Active Species
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2017 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, no 2, p. 1143-1149Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
Keywords
water oxidation, cobalt oxide, decomposition, surface characterization, thin film
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-203830 (URN)10.1021/acscatal.6b01815 (DOI)000393539200026 ()2-s2.0-85012893978 (Scopus ID)
Note

QC 20170321

Available from: 2017-03-21 Created: 2017-03-21 Last updated: 2017-11-29Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4093-1251

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