Size controllable CoNiP nanoparticle supported on porous carbon for highly-efficient electrocatalytic overall water splitting

Designing small size well-dispersed transition metal phosphides nanoparticles with more exposed catalytic sites and strong interfacial coupling properties is an efficient method for optimizing water splitting performance. Herein, various adjustable sizes of CoP/CoNiP nanoparticles securely anchored on asphalt-derived porous carbon (labeled as CoxNi1-xP/C) are successfully constructed by using preferred ethanol/water solvent. The as-obtained optimal 6-8 nm-sized Co 0.67 Ni 0.33 P/C achieves cutting-edge catalytic performance than the counterparts with an overpotential of 58 mV for hydrogen evolution reaction and 231 mV for oxygen evolution reaction at 10 mA cm-2 in 1.0 M KOH. Importantly, it requires an overpotential of 225 mV@500 mA cm-2 for HER superior to that of commercial Pt/C. Meanwhile, Co 0.67 Ni 0.33 P/C represents outstanding stability as proved by almost perfectly overlapping curves of current density in the long-time voltage cycles (3000 cycles) and negligible degradation after chronopotentiometry tests (up to 24 h) under 10 mA cm-2 . In catalyzing overall water splitting, just 1.59 V is obtained to accomplish 10 mA cm-2 using Co 0.67 Ni 0.33 P/C as both electrodes, surpassing most advanced bifunctional catalysts. By this research, we introduce an efficient synthetic strategy for creating carbon-based transition metal phosphides with small particle size and remarkable catalytic activity in new ways.