Great attention has been focused on the production of non-polluting gas fuel (hydrogen) from water electrolysis combined with renewable resources. However, the H2 bubble removal during water electrolysis is still challenging, which is a critical factor to improve the electrode performance of hydrogen evolution reaction (HER). Herein, a gradient porous electrode with decreasing pore size from the middle of the electrode to the two sides (SML-LMS-HE) was developed to accelerate H2 bubble removal rate by optimizing the pore size distribution of HER electrode. This electrode was prepared by using composite Ni foams with gradient porous structure as the conductive substrate, then being decorated with MoS2/Ni3S2 heteronanorods. The as-prepared electrode exhibited a much higher H2 bubble removal rate as compared with that of homogeneous porous HER electrode (MMM-MMM-HE) and gradient porous HER electrode with increasing pore size from the middle of the electrode to the two sides (LMS-SML-HE), conducive to the sufficient exposure of the active sites and the effective improvement of the electrode performance. As a result, SML-LMS-HE demonstrated a considerably low overpotential of 83 mV at the current density of 10 mA cm-2 as compared with MMM-MMM-HE and LMS-SML-HE.
Keywords hydrogenÂ evolutionÂ reaction,Â gradientÂ porous electrode,Â hydrogenÂ bubbleÂ transport