Black Phosphorus-Modified CoO through Tuning the Electronic Structure for Enhanced Oxygen Evolution Reaction.

Spinel CoO, consisting of two mixed valence states, Co and Co, has attracted enormous interest as a promising electrocatalyst for oxygen evolution reaction (OER). Proper control on the relative proportion of Co/Co in cobalt oxide can greatly tune the electronic structure and further optimize its catalytic performance. Herein, a hybrid coupling CoO with black phosphorus (CoO@BP) is designed as an efficient catalyst for OER. Electron migration from BP to CoO is achieved in CoO@BP, owing to the higher Fermi level of BP than that of CoO. Efficient electron transfer can not only create massive active sites with abundant Co but also remarkably suppress the deterioration of BP. Particularly, the CoO@BP catalyst outperforms the pristine CoO by over four times and is even 20 times higher than that of bare BP at a potential of 1.65 V versus reversible hydrogen electrode. Our finding provides insightful understanding for electronic engineering in CoO@BP by balancing advantages and utilizing drawbacks of CoO and BP.