Corrosion-engineered stereoscopic nano-microflower FeOOH for efficient electrocatalysis toward oxygen evolution reaction

Designing inexpensive and high-efficiency Fe(oxy)-hydroxide nanomaterials are essential to accelerate the sluggish kinetics of oxygen evolution reaction (OER). However, it is still a challenge to increase its electronic conductivity and exposure of the active site, as well as make it work under high current densities. Herein, a facile corrosion engineering strategy is proposed to in-situ synthesize the self-supporting Fe(oxy)-hydroxide heterostructures on nickel foam substrate in the corrosion system of “FeCl3-NaCl”. The morphologies and phase compositions characterization show that Cl- concentration can accelerate the oxygen corrosion process, while the concentration and species of metal irons can change the composition of the corrosion products. The synergistic effect of Cl- and Fe3+ enabled the FeOOH-Fe2.0 catalyst with stereoscopic nano-microflower structure, which owns abundant active sites, strong catalyst-base bond interaction, and fast electron transfer efficiency, reducing the potential reaction barrier of OER kinetics. Therefore, the obtained FeOOH-Fe2.0 provides a lower overpotential of 263 mV to achieve the current density of 100 mA cm−2 and a low Tafel slope of 64.03 mV dec−1 in 1 M KOH electrolyte. Furthermore, the FeOOH-Fe2.0 catalyst is used as an air electrode material to assemble Zn-air battery, which reaches the peak power density of 107.10 mW cm−2 and achieves long-term charge/discharge performance. This project offers a simple and effective method for preparing high-efficiency OER catalyst by corrosion strategy and confirms its application prospect in rechargeable Zn-air batteries.