Self-Supported Cu3P Nanowire Arrays as an Integrated High-Performance Three-Dimensional Cathode for Generating Hydrogen from Water

Searching for inexpensive hydrogen evolution reaction (HER) electrocatalysts with high activity has attracted considerable research interest in the past years. Reported herein is the topotactic fabrication of self‐supported Cu3P nanowire arrays on commercial porous copper foam (Cu3P NW/CF) from its Cu(OH)2 NW/CF precursor by a low‐temperature phosphidation reaction. Remarkably, as an integrated three‐dimensional hydrogen‐evolving cathode operating in acidic electrolytes, Cu3P NW/CF maintains its activity for at least 25 hours and exhibits an onset overpotential of 62 mV, a Tafel slope of 67 mV dec−1, and a Faradaic efficiency close to 100 %. Catalytic current density can approach 10 mA cm−2 at an overpotential of 143 mV. Down to the wire: Self‐supported Cu3P nanowire arrays on porous copper foam (Cu3P NW/CF) were derived from topotactic low‐temperature phosphidation of its Cu(OH)2 NW/CF precursor. As an integrated hydrogen‐evolving cathode, Cu3P NW/CF exhibits excellent catalytic activity and durability with nearly 100 % Faradaic efficiency in acidic aqueous electrolytes.