Inhibiting overoxidation of an α-MnO2 electrocatalyst by the lattice strain effect for efficient water oxidation

Abstract

The development of low-cost transition metal catalysts for use in alkaline water electrolysis (AWE) at high current densities is essential for achieving high-performance water splitting. Here, we reported a CrSb–MnO₂ catalyst, which shows a low overpotential of 263 mV at 100 mA cm⁻² and outstanding stability with only a small degradation of the catalyst after 100 h of operation at 1 A cm⁻² (1 M KOH). In addition, the catalyst also achieved excellent performance in AWE (1.69 V@1 A cm⁻²). This enhanced performance is not only due to lattice-strain engineering, which effectively modulates the electronic configurations of the active sites, but also due to bimetallic synergy, which improves the dynamics of metal–metal charge transfer. In situ differential electrochemical mass spectrometry (DEMS) and Fourier-transform infrared (FTIR) analyses revealed that the CrSb–MnO₂ catalyst preferred the adsorbate evolution mechanism (AEM) during the alkaline OER. This preference contributes to sustained stability under high current conditions in alkaline media. This work offers a novel approach for designing membrane electrodes that can operate efficiently and stably under large currents.