空位缺陷
塔菲尔方程
氧气
格式化
氧化物
化学
钴
密度泛函理论
二氧化碳
材料科学
无机化学
物理化学
计算化学
结晶学
催化作用
电化学
电极
冶金
有机化学
生物化学
作者
Shan Gao,Zhao-Yan Sun,Wei Liu,Xingchen Jiao,Xiaolong Zu,Qitao Hu,Yongfu Sun,Takeshi Yao,Wenhua Zhang,Shiqiang Wei,Yi Xie
摘要
The role of oxygen vacancies in carbon dioxide electroreduction remains somewhat unclear. Here we construct a model of oxygen vacancies confined in atomic layer, taking the synthetic oxygen-deficient cobalt oxide single-unit-cell layers as an example. Density functional theory calculations demonstrate the main defect is the oxygen(II) vacancy, while X-ray absorption fine structure spectroscopy reveals their distinct oxygen vacancy concentrations. Proton transfer is theoretically/experimentally demonstrated to be a rate-limiting step, while energy calculations unveil that the presence of oxygen(II) vacancies lower the rate-limiting activation barrier from 0.51 to 0.40 eV via stabilizing the formate anion radical intermediate, confirmed by the lowered onset potential from 0.81 to 0.78 V and decreased Tafel slope from 48 to 37 mV dec-1. Hence, vacancy-rich cobalt oxide single-unit-cell layers exhibit current densities of 2.7 mA cm-2 with ca. 85% formate selectivity during 40-h tests. This work establishes a clear atomic-level correlation between oxygen vacancies and carbon dioxide electroreduction.
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