Black Phosphorus-Modified Co3O4 through Tuning the Electronic Structure for Enhanced Oxygen Evolution Reaction.

Spinel Co3O4, consisting of two mixed valence states, Co2+ and Co3+, has attracted enormous interest as a promising electrocatalyst for oxygen evolution reaction (OER). Proper control on the relative proportion of Co2+/Co3+ in cobalt oxide can greatly tune the electronic structure and further optimize its catalytic performance. Herein, a hybrid coupling Co3O4 with black phosphorus (Co3O4@BP) is designed as an efficient catalyst for OER. Electron migration from BP to Co3O4 is achieved in Co3O4@BP, owing to the higher Fermi level of BP than that of Co3O4. Efficient electron transfer can not only create massive active sites with abundant Co2+ but also remarkably suppress the deterioration of BP. Particularly, the Co3O4@BP catalyst outperforms the pristine Co3O4 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 Co3O4@BP by balancing advantages and utilizing drawbacks of Co3O4 and BP.