Metal-organic frameworks derived carbon-incorporated cobalt/dicobalt phosphide microspheres as Mott–Schottky electrocatalyst for efficient and stable hydrogen evolution reaction in wide-pH environment

Cobalt phosphides, as low cost and abundant non-noble materials for hydrogen evolution reaction (HER), are always constrained by their inferior charge transfer and sluggish intrinsic electrocatalytic kinetics. In this work, carbon-incorporated Co/Co₂P microspheres (Co/Co₂P@C) as a novel Mott–Schottky catalyst were synthesized successfully via carbonization and gradual phosphorization of Co based metal-organic frameworks. The unique merits, including Mott-Schottky effect at the interface formed between metal Co and semiconductor Co₂P, the incorporated carbon-layer on the surface and the spherical structure endow Co/Co₂P@C with favorable electrical conductivity, preferable kinetics and long-term stability when it was evaluated as electrocatalyst for HER in wide-pH range. As a result, the Co/Co₂P@C with the optimized phosphorization degree delivers a benchmark current density of 10 mA cm⁻² at the low overpotential of 192 and 158 mV in acidic and alkaline electrolytes, respectively, with a remarkable stability (CV cycling for 3000 cycles and continuous electrolysis at the overpotential of 200 mV for 48 h). Therefore, the as-designed Co/Co₂P@C should be one of the most promising catalysts for HER application.