Wei Lianwei, Hu Jiaping, Liu Huimin, Zhang Wanqun, Zheng Hui, Wu Shusheng, Tang Kaibin
Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, P. R. China.
Department of Chemistry, University of Science and Technology of China, Hefei, 230026, P. R. China.
Dalton Trans. 2022 May 10;51(18):7100-7108. doi: 10.1039/d2dt00706a.
The high overpotential required for the oxygen evolution reaction (OER)-due to the transfer of four protons and four electrons-has greatly hindered the commercial viability of water electrolysis. People have been committed to the development of alternative precious metal-free OER electrocatalysts, especially electrocatalysts for alkaline media. In this study, we report the application of Sr(CoFe)O (SCF-H) perovskite oxide with a hexagonal phase structure in the field of OER electrocatalysis. Synthesized by a simple and universal sol-gel method, the SCF-H perovskite oxide shows prominent OER activity with an overpotential of 318 mV at a current density of 10 mA cm and a Tafel slope of only 54 mV dec, which is significantly better than the cubic phase structure SrCoFeO (SCF-C), benchmark noble-metal oxide RuO and BaSrCoFeO (BSCF). Compared with cubic SCF-C, the hexagonal SCF-H perovskite oxide has abundant surface oxygen species (O/O), a faster charge transfer rate, and a higher electrochemical surface area. In addition, the DFT calculation results show that the center of the O p-band of SCF-H is closer to the Fermi level than that of SCF-C, which leads to the better OER activity of SCF-H. This work finds that the new hexagonal structure perovskite may become a promising OER electrocatalyst.
由于析氧反应（OER）需要转移四个质子和四个电子，因此所需的高过电位极大地阻碍了水电解的商业可行性。人们一直致力于开发替代的无贵金属OER电催化剂，尤其是用于碱性介质的电催化剂。在本研究中，我们报道了具有六方相结构的Sr(CoFe)O（SCF-H）钙钛矿氧化物在OER电催化领域的应用。通过简单通用的溶胶-凝胶法合成的SCF-H钙钛矿氧化物表现出突出的OER活性，在电流密度为10 mA cm时过电位为318 mV，塔菲尔斜率仅为54 mV dec，明显优于立方相结构的SrCoFeO（SCF-C）、基准贵金属氧化物RuO和BaSrCoFeO（BSCF）。与立方相的SCF-C相比，六方相的SCF-H钙钛矿氧化物具有丰富的表面氧物种（O/O）、更快的电荷转移速率和更高的电化学表面积。此外，密度泛函理论（DFT）计算结果表明，SCF-H的O p带中心比SCF-C更接近费米能级，这导致SCF-H具有更好的OER活性。这项工作发现，新型六方结构钙钛矿可能成为一种有前景的OER电催化剂。
