Hierarchical porous Co-N-C supported multi-morphology Co2P for high-current-density water splitting

The development of high-performance water splitting electrocatalysts under high current densities that can be produced on a large scale is a significant challenge. In this study, we constructed a dual-function electrocatalyst (M-Co2P/Co-N-C), consisting of hierarchical porous Co-N-C and multi-morphology Co2P, through a simple one-step pyrolysis strategy. By incorporating high-viscosity slurry, we were able to increase the metallic single atom loading and prevent the agglomeration of Co2P nanostructures during pyrolysis. Electron transfer was observed at the interface of Co2P (ΔG°H > 0) and Co-N-C (ΔG°H < 0). Such synergistic effect optimized the H∗ binding energy around 0, thus improving the hydrogen evolution dynamics. Additionally, by controlling the amount of slurry, we were able to achieve unique multi-morphology Co2P composed of nanoparticles and nanorods that promoted fast mass transfer at high current densities. M-Co2P/Co-N-C exhibited extraordinary hydrogen evolution performance in 1.0 M KOH, with a low overpotential of 61 mV at a current density of 10 mA cm−2 (η10) as well as a small Tafel slope of 66 mV dec−1. Furthermore, M-Co2P/Co-N-C demonstrated even more superior performance compared to the benchmark Pt/C electrocatalyst at large current densities, indicating its potential for practical applications in mass hydrogen production.