Synergistic Heterostructural Interface of CoP and WC for High-Performance Wide pH-Universal Hydrogen Evolution Electrocatalysis

The development of cost-effective catalysts with high activity and stability over a wide pH range is urgent, but there are great challenges in the selection and design of catalyst materials. In this work, cobalt phosphide nanoparticles were modified onto tungsten carbide nanowire arrays (CoP@WC/CC) on carbon cloth substrate by a two-step method. The construction of CoP@WC heterostructure results in the downward shift of the d-band center, which optimizes the adsorption energy of catalyst and reaction intermediates. Meanwhile, the synergistic effect of CoP and WC contributes to the alkaline HER kinetic process. In addition, binder-free self-supporting nanoarray have excellent electrical conductivity, large specific surface area and strong structure, which is conducive to charge/matter exchange and catalyst stability. The results show that CoP@WC/CC can effectively drive HER over a wide pH range and exhibit better catalytic performance than the single component control sample. In 0.5 M H2SO4 and 1 M KOH, CoP@WC/CC can drive the current density of 10 mA cm-2 with only 52 and 70 mV, while showing excellent stability without obvious performance degradation during 100 hours of constant current test. A proton exchange membrane water electrolysis (PEMWE) using CoP@WC/CC catalyst operates stably for 200,000 s at 30 mA cm-2. This study provides a new reference for the design and development of high efficiency, low cost and wide pH-universal hydrogen evolution electrocatalysts.