Cobalt carbonate as an electro-catalyst for water oxidation.

Author(s) Patra, S.G.; Illés, E.; Mizrahi, A.; Meyerstein, D.
Journal Chemistry
Date Published 2019 Oct 23

Co(II) salts in the presence of HCO 3 - /CO 3 2- in aqueous solutions act as electro-catalysts for water oxidation. It comprises of several key steps: (i) A relatively small wave at an E pa ~ 0.71 V vs . Ag/AgCl due to the Co III/II redox couple. (ii) A second wave is observed at E pa ~ 1.10 V with a considerably larger current. In which the Co III undergoes oxidation to form a Co IV species. The large current is attributed to catalytic oxidation of HCO 3 - /CO 3 2- to HCO 4 - . (iii) A process with very large currents at > 1.2 V due to the formation of Co V (CO 3 ) 3 - which oxidizes both water and HCO 3 - /CO 3 2- . These processes depend on [Co II ], [NaHCO 3 ] and pH. Chronoamperometry at 1.3 V gives a green deposit. It acts as a heterogeneous catalyst for water oxidation. DFT calculations point out that Co n (CO 3 ) 3 n-6 , n = 4 & 5 are attainable at potentials similar to those experimentally observed.

DOI 10.1002/chem.201904051
ISSN 1521-3765
Citation Patra SG, Illés E, Mizrahi A, Meyerstein D. Cobalt carbonate as an electro-catalyst for water oxidation. Chemistry. 2019.

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