Boosting Electrocatalytic Oxygen Evolution by Cation Defect Modulation via Electrochemical Etching

Defects engineering is an efficient strategy to enhance the performance of electrode materials by modulating the local electronic structure but usually requires costly and complicated processing. Here, an electrochemical reduction etching method has been developed for controllable tailoring of the cationic defects in iron-based oxides under mild conditions. The optimized defective spinel-type iron nickel oxide exhibits an overpotential as low as 270 mV at 10 mA cm(-2) and a Tafel slope of only 33.8 mV dec(-1) for the oxygen evolution reaction (OER), outperforming the benchmark RuO2 and pristine oxide. Experiments and theoretical calculations reveal that Fe vacancies can enhance Ni-O covalency, increase the density of active sites, and optimize the surface electronic structure, which promote the water adsorption/ activation and moderate oxygen intermediate species adsorption, thus significantly enhancing OER activity. This work provides a promising approach to create cation deficiency and mechanistic insight to understand the vacancy-induced enhancement of oxygen electrocatalysis.

Automated summary

Defects engineering is an efficient strategy to enhance electrode material performance, but typically requires costly processing. A new electrochemical reduction etching method allows for controlled tailoring of cationic defects in iron-based oxides, leading to significantly improved oxygen evolution reaction activity by enhancing Ni-O covalency and increasing active sites density through Fe vacancies.