Atomically Dispersed Cr Doping Induced Oxide Pathway Mechanism of Hollow RuO2 to Boost Oxygen Evolution Stability for PEMWE

Abstract

Developing stable and efficient electrocatalysts for acidic oxygen evolution reactions (OER) is crucial for the commercialization of proton exchange membrane water electrolysis (PEMWE). Herein, we use the oxyphilic Cr to atomically doped RuO₂ hollow sphere and synthesize Cr_0.092-RuO₂ catalyst via a phase transition strategy. Theoretical and experimental results indicate that oxyphilic Cr can improve the adsorption of OH⁻, shorten the distance of bimetallic sites and promote the direct coupling of oxygen free radicals, causing the formation of the heterogeneous bimetallic oxide pathway mechanism (OPM), where Cr can serve as an electron donor to provide stable Cr-O─Ru bonds and effectively avoid the excessive oxidation of Ru. The electrocatalytic performance of Cr_0.092-RuO₂ is improved significantly, and it not only exhibits high OER activity (overpotential of 168 mV at 10 mA cm⁻²), but also outstanding catalytic stability (2800 h at 10 mA cm⁻²). As a result, the Cr_0.092-RuO₂-based PEMWE only needs 1.62 V at 1 A cm⁻² and runs stably for 400 h at 0.5 A cm⁻². In short, the OPM pathway of avoiding excessive oxidation of RuO₂ proposed here may be a useful strategy for developing highly efficient Ir-free OER catalysts for PEMWE.