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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Experimental and Theoretical Study of Cobalt Selenide as a Catalyst for O_2 Electroreduction
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Experimental and Theoretical Study of Cobalt Selenide as a Catalyst for O_2 Electroreduction

机译：硒化钴催化O_2电还原的实验和理论研究

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摘要

Cobalt sulfides have been known for more than 30 years to be active toward oxygen reduction, and cobalt selenides have shown less activity. In this paper, a theoretical analysis is made of the four-electron reduction reaction of oxygen to water over the mixed anion and cation (202) surface of the pentlandite structure Co_9-Se_8, one of several selenide phases. Reversible potentials for forming adsorbed reaction intermediates in acid are predicted using adsorption energies calculated with the Vienna ab initio simulation program (VASP) and the known bulk solution values together in a linear Gibbs energy relationship. Comparison with an earlier theoretical analysis of pentlandite structure Co_9S_8 shows that the overpotential is predicted to be larger for the selenide by around 0.22 V. Cobalt selenide electrodes of unspecified stoichiometry were prepared chemically on glassy carbon discs, and polarization curves were measured using rotating discs. When heat-treated at 900 °C, the onset potential for O_2 reduction was found to be 0.5 V (normal hydrogen electrode, NHE), whereas electrodes not subject to heat-treatment were inactive. For Co_3S_4, onset potentials in the literature are ~0.8 V (NHE), consistent with a ~0.3 V higher measured overpotential for the selenide. The theoretical predictions for the pentlandite sulfide and selenide surfaces are in qualitative agreement.
机译：已知硫化钴具有30多年的减氧活性，而硒化钴的活性却较低。在本文中，对五方硒化物结构之一的五方结构Co_9-Se_8的混合阴离子和阳离子（202）表面上的氧气与水进行四电子还原反应进行了理论分析。使用维也纳从头算模拟程序（VASP）计算的吸附能和已知的本体溶液值一起以线性吉布斯能量关系预测在酸中形成吸附反应中间体的可逆电位。与较早的对五方晶结构Co_9S_8的理论分析比较，表明硒化物的过电势预计会增大约0.22 V.化学计量未指定的硒化钴钴电极是在玻璃碳圆盘上化学制备的，并且使用旋转圆盘测量了极化曲线。在900°C热处理时，发现O_2还原的起始电位为0.5 V（正常氢电极，NHE），而未经热处理的电极则处于非活性状态。对于Co_3S_4，文献中的起始电势为〜0.8 V（NHE），与硒化物的实测过电势高〜0.3 V一致。对五氧化硫和硒化物表面的理论预测在定性上是一致的。

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