Volume 10, Issue 5 p. 862-875
Full Paper

A Robust Molecular Catalyst Generated In Situ for Photo- and Electrochemical Water Oxidation

Dr. Hussein A. Younus

Dr. Hussein A. Younus

State Key Laboratory of Advanced Technology for Materials, Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 P.R. China

School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070 P.R. China

National Research Tomsk Polytechnic University, Lenin Avenue 30, Tomsk, 634050 Russia

Chemistry Department, Faculty of Science, Fayoum University, Fayoum, 36514 Egypt

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Dr. Nazir Ahmad

Dr. Nazir Ahmad

State Key Laboratory of Advanced Technology for Materials, Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 P.R. China

School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070 P.R. China

National Research Tomsk Polytechnic University, Lenin Avenue 30, Tomsk, 634050 Russia

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Dr. Adeel H. Chughtai

Dr. Adeel H. Chughtai

State Key Laboratory of Advanced Technology for Materials, Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 P.R. China

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Dr. Matthias Vandichel

Dr. Matthias Vandichel

Center for Molecular Modeling, Ghent University, Technology Park 903, 9052 Zwijnaarde, Belgium

Department of Physics and Competence Center for Catalysis, Chalmers University of Technology, Fysikgränd 3, Göteborg, Sweden

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Dr. Michael Busch

Dr. Michael Busch

Department of Physics and Competence Center for Catalysis, Chalmers University of Technology, Fysikgränd 3, Göteborg, Sweden

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Prof. Kristof Van Hecke

Prof. Kristof Van Hecke

Department of Inorganic and Physical Chemistry, Laboratory of Organometallic Chemistry and Catalysis, Ghent University, Krijgslaan 281 (S-3), 9000 Ghent, Belgium

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Prof. Mekhman Yusubov

Prof. Mekhman Yusubov

National Research Tomsk Polytechnic University, Lenin Avenue 30, Tomsk, 634050 Russia

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Prof. Shaoxian Song

Prof. Shaoxian Song

School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070 P.R. China

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Prof. Francis Verpoort

Corresponding Author

Prof. Francis Verpoort

State Key Laboratory of Advanced Technology for Materials, Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 P.R. China

School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070 P.R. China

National Research Tomsk Polytechnic University, Lenin Avenue 30, Tomsk, 634050 Russia

Department of Inorganic and Physical Chemistry, Laboratory of Organometallic Chemistry and Catalysis, Ghent University, Krijgslaan 281 (S-3), 9000 Ghent, Belgium

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First published: 05 December 2016
Citations: 42

Graphical Abstract

Finding active catalytic species: An in situ generated cobalt catalyst efficiently conducts photo- and electrochemical water oxidation under near-neutral conditions. This work sheds light upon the ability to directly assemble molecular metal–organic catalyst films on the surface of different conducting electrodes for the potential molecular engineering of cobalt-based electrocatalytic films.

Abstract

Water splitting is the key step towards artificial photosystems for solar energy conversion and storage in the form of chemical bonding. The oxidation of water is the bottle-neck of this process that hampers its practical utility; hence, efficient, robust, and easy to make catalytic systems based on cheap and earth-abundant materials are of exceptional importance. Herein, an in situ generated cobalt catalyst, [CoII(TCA)2(H2O)2] (TCA=1-mesityl-1,2,3-1H-triazole-4-carboxylate), that efficiently conducts photochemical water oxidation under near-neutral conditions is presented. The catalyst showed high stability under photolytic conditions for more than 3 h of photoirradiation. During electrochemical water oxidation, the catalytic system assembled a catalyst film, which proved not to be cobalt oxide/hydroxide as normally expected, but instead, and for the first time, generated a molecular cobalt complex that incorporated the organic ligand bound to cobalt ions. The catalyst film exhibited a low overpotential for electrocatalytic water oxidation (360 mV) and high oxygen evolution peak current densities of 9 and 2.7 mA cm−2 on glassy carbon and indium-doped tin oxide electrodes, respectively, at only 1.49 and 1.39 V (versus a normal hydrogen electrode), respectively, under neutral conditions. This finding, exemplified on the in situ generated cobalt complex, might be applicable to other molecular systems and suggests that the formation of a catalytic film in electrochemical water oxidation experiments is not always an indication of catalyst decomposition and the formation of nanoparticles.