Well-defined CoP/Ni2P nanohybrids encapsulated in a nitrogen-doped carbon matrix as advanced multifunctional electrocatalysts for efficient overall water splitting and zinc–air batteries

Abstract

Rational design of efficient multifunctional electrocatalysts is of significant importance for clean energy conversion and storage systems, such as water electrolysis, fuel cells and rechargeable metal–air batteries. Herein, well-designed CoP/Ni₂P nanoparticles encapsulated in a nitrogen-doped carbon matrix (named as CoP/Ni₂P@NC), derived from an organic–inorganic metal phosphonate precursor, can not only efficiently catalyze the hydrogen evolution reaction at all-pH ranges, but also exhibit outstanding activities for oxygen evolution and oxygen reduction reaction in an alkaline environment. When CoP/Ni₂P@NC was used as both anode and cathode electrocatalysts for overall water splitting, a low cell voltage of 1.60 V was sufficient to drive a current density of 10 mA cm⁻². When employed as an air–cathode for rechargeable Zn–air batteries, CoP/Ni₂P@NC shows a high peak power density of 77 mW cm⁻² and a long-term cycle life of 100 cycles. The remarkable electrocatalytic performance arises from the inherent catalytic activity of CoP/Ni₂P, the unique N-doped core–shell structure and the strong synergistic interactions among CoP, Ni₂P and N-doped carbon. This work is expected to inspire the design of advanced, multifunctional and performance-oriented organic–inorganic metal phosphonate-derived catalysts for sustainable energy conversion technologies.