Dynamic Redox Induced Localized Charge Accumulation Accelerating Proton Exchange Membrane Electrolysis

The sluggish anodic oxygen evolution reaction (OER) in proton exchange membrane (PEM) electrolysis necessitates applied bias to facilitate electron transfer as well as bond cleavage and formation. Traditional electrocatalysis focuses on analyzing the effects of electron transfer, while the role of charge accumulation induced by the applied overpotential has not been thoroughly investigated. To explore the influence mechanism of bias-driven charge accumulation, capacitive Mn is incorporated into IrO₂ to regulate the local electronic structure and the adsorption behavior. The applied bias triggers dynamic redox reactions at the active sites, which introduce local charge accumulation on the surface of electrocatalyst. Under bias, Mn oxidation induced a noticeable pseudocapacitance in the pre-OER region, promoting the OER kinetics of iridium sites. Meanwhile, the increased oxygen vacancy formation energy further prevents the lattice oxygen activation. The PEM electrolyzer, equipped with optimal materials as an anode, operates at a low driving voltage of 1.637 V under 2.0 A cm^-2, maintaining stable performance for over 800 h with a low degradation rate (19.4 µV h^-1). This work provides insights into the performance of metal oxide catalysts in acidic environments and offers forward-looking strategies for enhancing the catalytic performance through dynamic redox induced capacitive behavior.