Low-crystalline NiCuP with elemental synergy for hydrogen evolution reaction in proton exchange membrane water electrolyzer.

[Display omitted] • NiCuP electrocatalysts were electrodeposited onto porous carbon paper. • Low-crystallinity of NiCuP facilitates the electron transfer kinetics. • Bimetallic NiCu and electron-rich P of NiCuP enhanced the HER performance. • Electrochemical active sites of NiCuP were increased by employing Cu foam support. • PEMWE with NiCuP/CF/CP cathode exhibited a current density of 0.35 A/cm2 at 2.0 V cell. Transition metal phosphide is a representative electrocatalyst for hydrogen production via water electrolysis, owing to its superior activity and stability. In this study, we prepare NiCuP electrocatalysts on porous carbon paper (CP) using facile electrodeposition, which is a simple technique to modulate the material properties by controlling the deposition parameters. In the half-cell test, their catalytic activities for hydrogen evolution reaction in an acidic medium are significantly affected by the composition and crystallinity. After the optimization, the low-crystalline NiCuP electrocatalyst with a high Cu/Ni ratio is transferred onto a 3D-structured copper foam (CF) support, which provides a larger electrochemical surface area. Then, the NiCuP/CF/CP electrode is used as the cathode of the proton exchange membrane water electrolyzer, and a reasonable single-cell performance is achieved for hydrogen production. [ABSTRACT FROM AUTHOR]