Modulation of Surface Structure and Electronic States of Defective Pd-Doped NiFe-Layered Double Hydroxide Bifunctional Electrocatalyst by Alkaline Etching for Zn–Air Batteries

Surface structure and electronic states are important parameters for bifunctional catalysts, especially in energy devices. Herein, the hierarchically porous defective Pd-doped NiFe-layered double hydroxide is prepared by electrodeposition and alkaline etching. The etching process increases the surface area to facilitate bifunctional catalysis of the oxygen reduction reaction/oxygen evolution reaction in Zn–air batteries (ZABs). Electrochemical assessment reveals inhibited oxidation of nickel hydroxide after alkaline etching and formation of the hybrid battery composed of Zn–Ni and ZABs, which shows high reversibility and stability. The results reveal an effective strategy to modulate the surface properties of bifunctional catalysts.