Experimental and Theoretical Study of Cobalt Selenide as a Catalyst for O2 Electroreduction
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- 作者：Ellen Vayner ; Reyimjan A. Sidik ; Alfred B. Anderson ; Branko N. Popov
- 刊名：Journal of Physical Chemistry C
- 出版年：2007
- 出版时间：July 19, 2007
- 年：2007
- 卷：111
- 期：28
- 页码：10508 - 10513
- 全文大小：268K
- 年卷期：v.111,no.28(July 19, 2007)
- ISSN：1932-7455
文摘
Cobalt sulfides have been known for more than 30 years to be active toward oxygen reduction, and cobaltselenides have shown less activity. In this paper, a theoretical analysis is made of the four-electron reductionreaction of oxygen to water over the mixed anion and cation (202) surface of the pentlandite structure Co9Se8, one of several selenide phases. Reversible potentials for forming adsorbed reaction intermediates in acidare predicted using adsorption energies calculated with the Vienna ab initio simulation program (VASP) andthe known bulk solution values together in a linear Gibbs energy relationship. Comparison with an earliertheoretical analysis of pentlandite structure Co9S8 shows that the overpotential is predicted to be larger forthe selenide by around 0.22 V. Cobalt selenide electrodes of unspecified stoichiometry were prepared chemicallyon glassy carbon discs, and polarization curves were measured using rotating discs. When heat-treated at 900
C, the onset potential for O2 reduction was found to be 0.5 V (normal hydrogen electrode, NHE), whereaselectrodes not subject to heat-treatment were inactive. For Co3S4, onset potentials in the literature are ~0.8V (NHE), consistent with a ~0.3 V higher measured overpotential for the selenide. The theoretical predictionsfor the pentlandite sulfide and selenide surfaces are in qualitative agreement.
C, the onset potential for O2 reduction was found to be 0.5 V (normal hydrogen electrode, NHE), whereaselectrodes not subject to heat-treatment were inactive. For Co3S4, onset potentials in the literature are ~0.8V (NHE), consistent with a ~0.3 V higher measured overpotential for the selenide. The theoretical predictionsfor the pentlandite sulfide and selenide surfaces are in qualitative agreement.