Exploration of electrocatalytic water oxidation properties of NiFe catalysts doped with nonmetallic elements (P, S, Se)

The introduction of non-metallic atoms (P, S, Se) has emerged as an effective way to improve the catalytic activity of transition metal based layered double hydroxides (LDHs) for oxygen evolution reaction. However, objective comparisons of the performance of heteroelement-doped catalysts are complicated by the lack of standardization both in the electrochemical tests and physicochemical analysis. Herein, we use a unified protocol for evaluating the catalytic activities of heteroelement-doped NiFe-LDHs and explore the reasons for the differences in their catalytic performance. Some regular results are found from comparing the properties of the heteroelement-doped catalysts: (1) the introduction of P/S/Se can optimize the redox behaviors of Ni species, which is conducive to regulating adsorption energy of intermediates and the formation of high-valent active sites; (2) the specific area of catalysts was expanded after heteroelements doping, ensuring a more favorable structure for heterogeneous catalysis; (3) All P/S/Se-doped catalysts showed better activities when compared to the original NiFe LDHs in alkaline solutions, and the catalysts doped with S showed the best performance (Se < P < S).