材料科学
X射线光电子能谱
过电位
密度泛函理论
氧气
费米能级
催化作用
价(化学)
空位缺陷
电化学
碳纤维
化学工程
物理化学
结晶学
电极
计算化学
化学
复合材料
电子
工程类
物理
有机化学
复合数
量子力学
生物化学
作者
Hui Yuan,Jiantao Li,Wei Yang,Zechao Zhuang,Yan Zhao,Liang He,Lin Xu,Xiaobin Liao,Ruiqi Zhu,Liqiang Mai
标识
DOI:10.1021/acsami.8b01209
摘要
Rationally generating oxygen vacancies in electrocatalysts is an important approach to modulate the electrochemical activity of a catalyst. Herein, we report a remarkable enhancement in oxygen reduction reaction (ORR) activity of NiCo2O4 supported on hollow carbon spheres (HCS) achieved through generating abundant oxygen vacancies within the surface lattice. This catalyst exhibits enhanced ORR activity (larger limiting current density of ∼-5.8 mA cm-2) and higher stability (∼90% retention after 40 000 s) compared with those of NiCo2O4/HCS and NiCo2O4. The results of X-ray photoelectron spectroscopy (XPS) characterizations suggest that the introduction of oxygen vacancies optimizes the valence state of active sites. Furthermore, we carried out density functional theory (DFT) calculations to further confirm the mechanism of oxygen vacancies, and results show that oxygen vacancies enhance the density of states (DOS) near the Fermi level, decrease work function, and lower the calculated overpotential of NiCo2O4.
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