Hydroxyl-rich KIr4O8 Nanowires Promote Acidic Water Oxidation Electrocatalysis with Industrial Current Density

Abstract

Achieving high performance over Ir-based catalysts is still an enormous challenge for oxygen evolution reaction (OER) in acidic condition. Herein, we report that hydroxyl-rich KIr4O8 nanowires with more exposed active sites exhibit excellent catalytic activity and stability toward acidic OER. KIr4O8 nanowires anode catalyst shows a current density of 2.1 A/cm2 at 2 V in proton exchange membrane water electrolyzer. Combining in situ Raman spectroscopy and electrochemical mass spectroscopy results, we propose the modified adsorbate evolution mechanism that rich hydroxyl in inherent structure of KIr4O8 nanowires directly participants in the catalytic process for favoring the OER. Density functional theory calculation results further suggest that the enhanced proximity between Ir (d) and O (p) band center in KIr4O8 can strengthen the covalence of Ir-O, facilitate electron transfer between adsorbents and active sites, and decrease the energy barrier of rate-determining step during the OER.