Exciting lattice oxygen of nickel–iron bi-metal alkoxide for efficient electrochemical oxygen evolution reaction

Abstract

High efficiency, cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems. The electro-oxidation of water to oxygen plays a crucial role in such energy conversion technologies. Herein, we report a robust method for the synthesis of a bimetallic alkoxide for efficient oxygen evolution reaction (OER) for alkaline electrolysis, which yields current density of 10 mA cm⁻² at an overpotential of 215 mV in 0.1 M KOH electrolyte. The catalyst demonstrates an excellent durability for more than 540 h operation with negligible degradation in activity. Raman spectra revealed that the catalyst underwent structure reconstruction during OER, evolving into oxyhydroxide, which was the active site proceeding OER in alkaline electrolyte. In-situ synchrotron X-ray absorption experiment combined with density functional theory calculation suggests a lattice oxygen involved electrocatalytic reaction mechanism for the in-situ generated nickel–iron bimetal-oxyhydroxide catalyst. This mechanism together with the synergy between nickel and iron are responsible for the enhanced catalytic activity and durability. These findings provide promising strategies for the rational design of non-noble metal OER catalysts.