Co₃O₄ Nanowire Arrays toward Superior Water Oxidation Electrocatalysis in Alkaline Media by Surface Amorphization

It is highly desirable to develop a simple, fast and straightforward method to boost the alkaline water oxidation of metal oxide catalysts. In this communication, we report our recent finding that the generation of amorphous Co-borate layer on Co₃ O₄ nanowire arrays supported on Ti mesh (Co₃ O₄ @Co-Bi NA/TM) leads to significantly boosted OER activity. The as-prepared Co₃ O₄ @Co-Bi NA/TM demands overpotential of 304 mV to drive a geometrical current density of 20 mA cm^-2 in 1.0 M KOH, which is 109 mV less than that for Co₃ O₄ NA/TM, with its catalytic activity being preserved for at least 20 h. It suggests that the existence of amorphous Co-Bi layer promotes more CoO_x (OH)_y generation on Co₃ O₄ surface.