▎ 摘　　要

Herein, a scalable and facile strategy is presented to fabricate ultra-small nickel phosphide nanoparticles loaded reduced graphene oxide on nickel foam (Ni2P/RGO@NF) through an interfacial redox reaction between GO and NF in water, followed by a simple phosphorization process. This self-supported Ni2P/RGO@NF catalyst with favorable 3D hierarchical nanostructure, enhanced electrical conductivity and high density of ultra-small Ni2P (24,000 particles per square micron) shows outstanding bifunctional catalytic performance toward overall water splitting under alkaline and neutral conditions. Notably, the Ni2P/RGO@NF electrode delivers low cell voltage of just 1.58V and 1.68V at a current density of 10 mA cm(-2) in alkaline and neutral electrolytes with prominent stability for more than 20 h, respectively. Moreover, ultra-small cobalt phosphide loaded RGO on cobalt foam samples have also been prepared by the same method. Thus, this strategy provides a general way for fabricating self-supported electrocatalysts with ultra-small metal-based nanoparticles, which is scalable and applicable in energy storage and conversion devices. (C) 2020 Elsevier Ltd. All rights reserved.