Chu Hongqi, Zhang Dan, Feng Panpan, Gu Yulong, Chen Pen, Pan Kai, Xie Haijiao, Yang Min
MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Institution Harbin Institute of Technology, Harbin 150001, China.
Key Laboratory of Functional Inorganic Material Chemistry (MOE), School of Chemistry and Materials Science, Heilongjiang University, Harbin, 150080, China.
Nanoscale. 2021 Dec 2;13(46):19518-19526. doi: 10.1039/d1nr05747b.
Efficient electrocatalyst materials for several applications, including energy storage and conversion, have become vital for achieving technological progress. In this work, a CoO@CoO/C composite with abundant oxygen vacancies was successfully synthesized. The concentration of the oxygen vacancies was well controlled by changing the degree of vacuum during the heat treatment and was characterized by XPS and EPR. The existence of the porous structure arising from the cobalt oxide particles embedded in the carbon matrix provided an efficient charge and gas transmission path, significantly improving the performance of electrocatalytic oxygen evolution. Sufficient reactive sites were provided from both the oxygen vacancies and the heterogeneous interface. The mechanism of enhanced OER originating from the built-in electric field derived from oxygen vacancies was investigated. Consequently, the CoO@CoO/C composites offered an OER overpotential of 287 mV at a current density of 10 mA cm with good stability in 1 mol L KOH. In addition, combined with surface photovoltage (SPV), transient photovoltage (TPV), DFT, and Raman spectroscopy, the effect of oxygen defects on the electron migration ability and transformation of the intermediate products were investigated to further understand the nature of catalytic activity in OER.
包括能量存储和转换在内的多种应用的高效电催化剂材料，对于实现技术进步至关重要。在这项工作中，成功合成了具有丰富氧空位的CoO@CoO/C复合材料。通过改变热处理过程中的真空度，氧空位浓度得到了很好的控制，并通过XPS和EPR进行了表征。嵌入碳基体中的氧化钴颗粒形成的多孔结构提供了有效的电荷和气体传输路径，显著提高了电催化析氧性能。氧空位和异质界面都提供了足够的反应位点。研究了源自氧空位的内建电场增强析氧反应的机理。因此，CoO@CoO/C复合材料在1 mol L KOH中，在电流密度为10 mA cm时的析氧过电位为287 mV，具有良好的稳定性。此外，结合表面光电压（SPV）、瞬态光电压（TPV）、密度泛函理论（DFT）和拉曼光谱，研究了氧缺陷对电子迁移能力和中间产物转化的影响，以进一步了解析氧反应中催化活性的本质。
