Kirkendall oxidation tailors lattice strain in transition metal oxides for efficient oxygen electrocatalysis

Summary

Advanced electrocatalysts for oxygen reduction/evolution reaction (ORR/OER) are pivotal to clean energy conversions. Lattice strain has been found to effectively enhance catalytic performance in transition metal oxides (TMOs), but precise control is challenging with conventional bulk processing methods. Herein, we report the regulation of lattice strain (ranging from 0% to 2.2%) in TMOs through Kirkendall diffusion, enabling us to chart the strain-dependent electrocatalysis. The Co₃O₄ 400 plane with an optimal 1.8% tensile strain delivers an ORR half-wave potential of 0.86 V and a small OER overpotential of 0.30 V at 10 mA cm⁻² in alkaline environments, located among the top TMO-based electrocatalysts. X-ray absorption spectra and density functional theory calculations collectively suggest that tensile strain simultaneously optimizes the adsorption of ^∗OOH and the desorption of ^∗OH on adjacent Co atoms. This work provides new insights into regulating strain in TMOs for advanced oxygen electrocatalysis, which is extendable to other catalytic applications.