Self-Supported NiSe₂ Nanowire Arrays on Carbon Fiber Paper as Efficient and Stable Electrode for Hydrogen Evolution Reaction

NiSe₂ nanowire (NW) arrays grown on flexible carbon fiber paper (CFP) were synthesized, for the first time, through a novel thermal selenization method in vacuum instead of flowing inert gas. The ultrathin NiSe₂ NWs uniformly cover the CFP, contributing to the large surface area and fast charge transportation. Desirably, this binder-free and hierarchical electrode shows favorable activity for hydrogen evolution reaction (HER). It only requires an overpotential of 172 mV to afford the current density of 100 mA cm^-2 in 0.5 M H₂SO₄, corresponding to a low Tafel slope of 32.44 mV dec^-1. After 1000 continuous cycles, the HER activity of NiSe₂ NWs is well-maintained. Moreover, the current density remains unchanged in prolonged electrolysis, indicating an excellent durability of NiSe₂ NWs. The novel preparation method described in this study could inspire future work on the synthesis of transition-metal dichalcogenides with high purity and ultrasmall nanostructure toward improved electrocatalytic activity.