Optimizing the active interface structure of MnO2 to achieve sustainable water oxidation in an acidic medium

Abstract

Developing cost-effective electrocatalysts for the oxygen evolution reaction (OER) in proton exchange membrane (PEM) water electrolysis is crucial to achieving large-scale hydrogen production through water electrolysis. Here, we propose the utilization of a compound Er₂O₃ to enhance the catalytic performance of MnO₂ in acidic OER. In situ Raman and DFT calculations reveal that Er₂O₃ not only suppresses the phase transition of MnO₂ but also undergoes dissolution at the interface, thereby optimizing the structure of the active catalytic layer. The optimization of the Mn active site through the incorporation of robust Mn–O bonds in the catalytic interface layer, along with the accumulation of active MnO species during OER, are both pivotal factors for enhancing catalytic performance. Due to these inherent advantages, the MnO₂@Er₂O₃ heterostructure catalyst exhibits a low overpotential of 342 ± 5 mV at a current density of 10 mA cm⁻². The long-term stability test at a high current density of 50 mA cm⁻² for 20 h exhibited no significant performance degradation. This study develops a cost-effective electrocatalyst for acidic OER and provides a new avenue for developing low-cost electrocatalysts for OER under acidic conditions in water electrolysis.