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 Cu 3 P nanowire arrays on commercial porous copper foam (Cu 3 P 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, Cu 3 P 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.