Ultrathin 2D nanosheet based 3D hierarchical hollow polyhedral CoM/C (M = Ni, Cu, Mn) phosphide nanocages as superior electrocatalysts toward oxygen evolution reaction

[Display omitted] •A general ion-inducing method was developed to obtain the unique electrocatalyst.•The doped C and the secondary metal help to modulate the electronic structure.•The hollow structure and 2D nanosheets collaborate to optimize the mass activity.•Extrinsic morphology and intrinsic electronic modulation synergistically boost OER. Metal phosphide materials with unique nanostructures are of great interest for electrocatalysis. Herein, an ion-induction strategy is developed to synthesize a family of carbon incorporated homobimetallic (CoNi/C, CoCu/C, CoMn/C) phosphide electrocatalyst of hierarchical hollow polyhedral nanocages (HHPNCs) composed of ultrathin 2D subunits. The unique morphological structure effectively optimize the surface active sites, accelerate the charge transfer, and thus boost their superior catalytic activity. Density functional theory calculations reveal that not only the homogenously doped secondary metals but also the incorporated carbon effectively regulates the electronic structure and as a result collaboratively lower the kinetic energy barrier for the OER. Electrochemical measurements show high OER efficiency (η@10 mA cm−2 = 267, 262, and 283 mV for samples of CoNi/C-, CoMn/C-, and CoCu/C-HHPNC, respectively) and durability in alkaline electrolytes. Especially, the prepared carbon incorporated homobimetallic HHPNCs show very much higher (almost 9 times) mass activity than the particle counterpart.