Constructing surface concave defects on NiFe layered double hydroxides by electrochemical reduction for efficient oxygen evolution reaction

NiFe-LDH has been proved to be one of the most effective non-noble metals electrocatalysts for oxygen evolution reaction, but inadequate exposure of the active sites prevents its performance from being comparable to noble metal catalysts. Herein, we prepare 3D nanoflower-like NiFe-LDH composed of bumpy, thin nanosheets by hydrothermal combined with electrochemical reduction method. Various characterization results reveal that the nanosheets of NiFe-LDH are partial exfoliated and reduced by the atomic H* and H2 in the electrochemical reduction process, which results in the generation of surface oxygen vacancies (Vos), forming plenty concave defects in the surface of nanosheets. The optimized partially surface reduced NiFe-LDH exhibits an outstanding catalytic activity for OER with long-term stability. The overpotential is only 185 mV at 100 mA cm-2 with no obvious deterioration in 100 h operation process. The enhanced activity is attributed to the more exposure and the adjustment of electron density of metal active sites. This work provides a universality method to strip nanosheets and induce oxygen vacancies on oxygenated catalysts.