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A Robust Molecular Catalyst Generated In Situ for Photoand Electrochemical Water Oxidation

H. A. Younus ; N. Ahmad ; A. H. Chughtai ; Matthias Vandichel (Institutionen för fysik, Kemisk fysik (Chalmers)) ; Michael Busch (Institutionen för fysik, Kemisk fysik (Chalmers)) ; K. Van Hecke ; M. Yusubov ; S. X. Song ; F. Verpoort
ChemSusChem (1864-5631). Vol. 10 (2017), 5, p. 862-875.
[Artikel, refereegranskad vetenskaplig]

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, [Co-II(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.

Nyckelord: cobalt, electrochemistry, oxidation, photochemistry, water splitting

Denna post skapades 2017-05-03.
CPL Pubid: 249104


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