3D hierarchical porous N-doped carbon nanoarchitecture coated bimetallic phosphides as a highly efficient bifunctional electrocatalyst for overall water splitting

Abstract

As the energy and ecological crises are increasingly grim, it is challengeable but extremely attractive to fabricate highly efficient and low-cost bifunctional electrocatalysts for overall water splitting (OWS). Herein, a bimetallic phosphide embedded in N-doped hierarchical porous carbon (CoP/Ni2P@NHPC) framework was successfully constructed by calcination and phosphorization of cobalt–nickel coordination polymer nanoflowers (Co/Ni CPNFs), which were obtained by a facile hydrothermal process. Benefitting from their fascinating architecture and composition, the as-prepared CoP/Ni2P@NHPC exhibits outstanding electrochemical properties for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) with small Tafel slopes (103.9 mV dec-1, 62.58 mV dec-1) and ultralow overpotentials (275 mV, 159 mV at 10 mA cm−2) in alkaline medium. Additionally, the CoP/Ni2P@NHPC can be used as a bifunctional catalyst in a two-electrode water splitting device, and it only requires a low cell voltage of 1.55 V to attain the current density of 10 mA cm−2. Meanwhile, the CoP/Ni2P@NHPC also present admirable durability (at least 20 h) under long-term electrolysis. This work gives inspiration for the preparation of highly active bifunctional electrocatalysts for OWS.