Prussian blue analogue derived cobalt–nickel phosphide/carbon nanotube composite as electrocatalyst for efficient and stable hydrogen evolution reaction in wide-pH environment

Transition metal phosphides, especially bimetallic phosphides, are promising noble-metal-free electrocatalysts for hydrogen evolution reaction (HER). However, their inferior charge transfer ability constrains further performance improvement. In this work, a facile strategy is reported to fabricate Co₂P/Ni₂P/carbon nanotube (CNT) composite from a precursor Co-Ni Prussian blue analogue. The combination of Co₂P/Ni₂P and CNT endows Co₂P/Ni₂P/CNT with improved electrical conductivity and a richer electrochemically active surface area. As a result, the Co₂P/Ni₂P/CNT composite exhibits desirable HER activities across a wide pH range, delivering a benchmark current density of 10 mA cm⁻² at overpotentials as low as 151 and 202 mV in 0.5 M H₂SO₄ and 1 M KOH electrolytes, respectively, as well as remarkable electrocatalytic stabilities over 48 h in both electrolytes. This strategy enables the design of high-performance electrocatalysts for efficient and stable hydrogen generation.