Electrochemically fabricated hierarchical porous Ni(OH)2/NiCu electrodes for hydrogen evolution reaction

•We brush-plated NiCu layer instead of conventional electrodeposition.•Deposition-dealloying cycles was done to roughen the surface of NiCu layer.•Selective dissolution of Cu was done to fabricate a hierarchical porous structure.•The roughened porous NiCu layer was dipped in NiCl2 solution.•Porous Ni(OH)2/NiCu electrode has the best HER activity of all the electrodes.

A hierarchical porous Ni(OH)2/NiCu electrode was fabricated by a novel electrochemical method, which included brush plating, cyclic voltammetry (CV) treatment, electrochemical dealloying and hydrolysis. We firstly discussed the feasibility of using brushing plating to produce NiCu precursors. Then we found that the CV treatment can be used to yield a roughened NiCu surface; thereafter, the selective dissolution of Cu can be used to further improve the surface area. Through controlling the cycle number and time of dealloying, we can get a hierarchical porous NiCu which exhibit highest hydrogen evolution reaction activity. Subsequently, the obtained hierarchical porous NiCu immersed in 0.1 M NiCl2 to get a hierarchical porous Ni(OH)2/NiCu electrode. The influence of immersing time was also discussed. The fabricated hierarchical porous Ni(OH)2/NiCu electrode exhibits higher hydrogen evolution reaction (HER) activity than those of the brush-plated NiCu and porous NiCu electrodes, which can be attributed to the unique hierarchical porous structure and the synergy between the Ni(OH)2 and NiCu surfaces.