Se induced underpotential deposition of amorphous CoSe2 ultrathin nanosheet arrays as high-efficiency oxygen evolution electrocatalyst for zinc-air battery

Abstract Zinc-air battery is regarded as an ideal candidate for next-generation energy conversion and storage devices, but its conversion efficiency is mainly limited by the sluggish kinetics of oxygen evolution reaction (OER). Therefore, development of highly active and durable non-noble-metal OER catalysts is of great significance to promote its industrialization process. Herein, we electrodeposit amorphous CoSe2 ultrathin nanosheet arrays which exhibit a low overpotential of ∼0.287 V at 10 mA cm-2 and a Tafel slope of ∼62 mV dec-1 toward the OER in 1 M KOH. This catalytic activity is superior to its crystalline counterpart, commercial RuO2 and most of the reported Co-based catalysts. It can be mainly attributed to the lowered adsorption free energy of OER intermediates and improved charge transfer ability with phase transformation from crystalline state to amorphous state, beside the intrinsic catalytic activity of CoSe2. When serving as an air cathode in zinc-air battery, the amorphous CoSe2 also realizes a larger power density and better long-term cyclability compared with those of crystalline CoSe2 and Pt/C-RuO2 electrodes. This work offers a new underpotential deposition strategy to fabricate high-activity amorphous catalysts, and demonstrates its great potential for practical applications.