Highly active porous nickel-film electrode via polystyrene microsphere template-assisted composite electrodeposition for hydrogen-evolution reaction in alkaline medium

A highly porous nickel-film electrode with satisfactory mechanical strength was prepared by a facile vertical template-assisted composite electrodeposition method using polystyrene (PS) microspheres templates, with the aim of improving the electrocatalytic activity for the hydrogen-evolution reaction (HER). During the composite electrodeposition process, the hydrophobic PS microspheres were highly dispersed in the electrolyte with the help of a surfactant, and then co-deposited with Ni to form the film electrode. After removing the PS templates by annealing, a porous Ni film containing large amount of uniformly dispersed pores with narrow size distribution was obtained, and then applied as the electrode for the HER in an alkaline medium. As evidenced by the electrochemical analysis, the porous Ni film electrode exhibits higher catalytic activity as compared to a dense Ni film electrode and is superior to a Ni/RuO2/CeO2 commercial electrode. The effect of temperature on the catalytic properties of the porous Ni film electrode was also investigated; the activation energy was calculated as 17.26 kJ/mol. The enhanced activity toward the HER was attributed to the improved electrochemical surface area and mass transportation facilitated by the high porosity of the synthesized Ni film electrode.