In situ growth of cobalt@cobalt-borate core-shell nanosheets as highly-efficient electrocatalysts for oxygen evolution reaction in alkaline/neutral medium

Development of efficient non-noble metal electrocatalysts for oxygen evolution reaction (OER) is still a crucial issue for renewable energy technologies. Herein, we report a core-shell-like catalyst of amorphous cobalt borate nanosheets grown on metallic cobalt deposited on Ti-mesh (Co@Co-Bi/Ti) by an in situ conversion strategy. Benefiting from the high activity, large surface area of Co-Bi nanosheets, outstanding electronic conductivity of metallic Co and the 3D structure inherited from Ti-mesh substrate, Co@Co-Bi/Ti shows high OER activity with a relatively small overpotential of 329 mV to obtain a current density of 10 mA cm(-2), a low Tafel slope of 46 mV dec(-1) and an accessible large current density of 500 mA cm(-2) in alkaline solution. Besides, Co@Co-Bi/Ti exhibits good performance in a near-neutral medium. This study provides an effective pathway to improve the cobalt metal based materials.