Aligned porous nickel electrodes fabricated via ice templating with submicron particles for hydrogen evolution in alkaline water electrolysis

Though a large number of nickel-based catalysts have been applied to alkaline water electrolysis, the effect of the catalyst structure on hydrogen evolution reaction (HER) is often ignored. In this work, aligned porous nickel electrodes (APNEs) are fabricated by ice templating and tested for HER in 1 M KOH electrolyte. Compared to isotropic porous structures, such as nickel foam and nickel fiber felt, the present anisotropic porous structure with aligned channels has a smaller pore size, larger area of electrocatalytic activity, and stronger bubble removal ability, resulting in outstanding HER performance. Three kinds of nickel powders with different diameters are also used to prepare APNEs. The results show that the particle size plays a dominant role in the structure: smaller particles lead to wider pores and thinner walls with more protuberances. The APNE-A prepared with the smallest particles shows the most outstanding HER performance, with a minimum overpotential of 101 mV at 10 mA cm−2 and a Tafel slope of 94.3 mV dec−1. And the analysis results of stability tests and electrolytic voltage efficiency further support the positive effect of the structure on HER performance.