Phase-Controlled Cobalt Phosphide Nanoparticles Coupled with N, P, S Co-Doped Hollow Carbon Polyhedrons as Efficient Catalysts for Both Alkaline and Acidic Hydrogen Evolution

Tailoring cobalt phosphide electrocatalysts with a tunable phase and morphology is of great importance for the advancement of hydrogen evolution reaction (HER). The synthesis of phase- and morphology-modulated hollow cobalt phosphide nanoparticles coupled with N, P, S co-doped carbon (Co-P@NPS-C) polyhedrons through a facile three-step method is reported. Benefiting from the cooperation of structural features, heteroatoms doping, and catalytic components (Co x P, a mixture of CoP and Co 2 P), the hollow Co x P@NPS-C polyhedrons exhibit superior HER performance and long-term stability in 1.0 m KOH solution, with a low onset potential value (18 mV), an overpotential of 80 mV at 10 mA cm −2 , and a small Tafel slope of 57.6 mV dec −1 . In addition, the Co x P@NPS-C electrodes exhibit good electrochemical properties and stability in 0.5 m H 2 SO 4 solution. These results suggest a novel and promising coating approach with poly(cyclotriphosphazene- co -4,4′-sulfonyldiphenol (PZS) to fabricate other heterogeneous catalysts for various applications.