Geometrical Engineering of Spinel Oxide Solid Solution to Enhance the Oxygen Evolution Reaction

Abstract

Thanks to their outstanding activity, spinel oxides are generally regarded as a potential noble metal-free electrocatalyst as a substitute for noble metals in the oxygen evolution reaction. The design and regulations of octahedral geometry have been considered to be the most feasible strategy to enhance the OER performance on spinel oxides. In this report, to promote the catalytic activity of OER, two strategies have been applied to regulate the octahedral geometry of spinel oxide solid solution, including construction of a large number of active sites by filling the foreign cations into the unoccupied octahedral interstices and exposure of multiple active sites. The as-prepared iron foam (IF)-supported solid solution of MoxNi1–xFe2O4 (the atomic ratio of Mo:Ni is 1.05:10) nanosheets (MNFO NS/IF) exhibits efficient catalytic activity (achieving low overpotentials of 250 and 281 mV at current densities of 10 and 100 mA cm–2), fast kinetics (with a lower Tafel slope of only 36.9 mV dec–1), and high durability (maintaining the OER performance at 100 mA cm–2 over 120 h).