Double-template fabrication of three-dimensional porous nickel electrodes for hydrogen evolution reaction

Three-dimensional (3D) porous nickel structures were fabricated via a double-template electrochemical deposition process. The construction of the foam structures was achieved by means of a hydrogen bubble dynamic template, prepared from Cu electrodeposition at high current densities. Subsequently, a Ni layer was electrodeposited on the Cu 3D template. During the nickel coating, the typical finger-like microstructure of the Cu foam becomes denser and changes to a cauliflower microstructure. The hydrogen evolution reaction (HER) on these macroporous Ni electrodes was evaluated in 30 wt.% KOH solution by means of polarization curves and electrochemical impedance spectroscopy (EIS). Results demonstrate greater apparent activity of the developed electrodes towards HER in comparison with commercial smooth Ni electrode. The 3D porous Ni electrocatalyst obtained from Cu templates synthesized at the lowest current density and the highest electrodeposition time yielded the best electrochemical activity for HER.

► Three-dimensional Ni structures have been successfully created by a double-template procedure. ► The catalysts manifest greater activity towards HER in comparison with smooth Ni electrode. ► A fraction of the inner surface of the electrode is blocked during HER due to gas bubbles. ► The higher the pore sizes of the macroporous catalyst, the higher the electrode activity.