High-valence metal-doped amorphous IrOx as active and stable electrocatalyst for acidic oxygen evolution reaction

Abstract

Proton-exchange membrane water electrolysis, particularly driven by renewable electricity, is a sustainable strategy for green hydrogen production. However, developing highly active and stable electrocatalysts to accelerate the oxygen evolution reaction (OER) remains challenging. Herein, we introduce an effective strategy for constructing high-valence metal-doped IrOx with abundant oxygen vacancies, while simultaneously enhancing the catalytic activity and stability of the acidic OER. The synthesized Ta-doped IrOx (350-Ta@IrOx) exhibits ultramicroscopic nanoparticle morphology and abundant surface oxygen vacancies</a>, enabling a rapid OER process with a low overpotential of 223 mV at 10 mA cm-2 and 147.7 times higher mass activity (1207.4 A gIr−1) than that of commercial IrO2 at 1.55 V</a> versus the reversible hydrogen electrode. More importantly, 350-Ta@IrOx affords excellent stability with insignificant potential degradation after 500 h of electrolysis at 10 mA cm2, originating from the low operating potential and suppressed dissolution and oxidation of oxygen vacancy active sites via Ta doping. Density functional theory calculations suggest that Ta doping and oxygen defect engineering are effective in facilitating the nucleophilic attack of water molecules, thereby accelerating the rate-determining step toward high catalytic OER activity on Ta-doped IrOx. We anticipate that this study will provide an effective method to obtain active and stable electrocatalysts via high-valence metal doping.