Hierarchical Co(OH)2/Ni(OH)2 nanosheets coupled with black phosphorus for enhanced oxygen evolution electrocatalysis

Improving the electrocatalytic performance of transition metal hydroxides in the oxygen evolution reaction (OER) is crucial for advancing efficient electrochemical water splitting. Herein, through a multi-step electrodeposition strategy, a novel composite material was successfully developed, consisting of thin black phosphorus (BP) layers, Co(OH) 2 nanosheets, and Ni(OH) 2 nanoflowers (referred to as Co-BP-Ni), for efficient OER electrocatalysis. We found that there is a unique electron donor-acceptor heterointerface between BP and Co(OH) 2 /Ni(OH) 2 (Co-Ni), where surface active electrons migrate from BP to the metal hydroxides. Comprehensive characterization confirmed that this coupling not only generated many active sites but also enhanced mass transport efficacy. Accordingly, the optimized Co-BP-Ni composite material has an overpotential as low as 163 mV at 10 mA cm -2 and maintains good structural stability. Most importantly, this work provides fundamental guidance for designing highly active black phosphorus or transition metal hydroxide-based electrocatalysts through interface electron regulation.