Novel porous tungsten carbide hybrid nanowires on carbon cloth for high-performance hydrogen evolution

Abstract

The platinum-like behavior of tungsten carbides has made them one of the most promising electrocatalysts for the hydrogen evolution reaction (HER). So far, however, their poor activity has kept them far away from practical application. Related research has been basically focused on the form of particles with poor nano-structures, which is not conducive to further development. There is an urgent need to develop a versatile and facile method to synthesize tungsten carbide nanostructures with high active site density. Here we developed a plasma-assisted carburization method to synthesize porous tungsten carbide hybrid nanowires (p-WC_x NWs) on carbon cloth. Benefitting from the rapid carburization process with a unique etching-effect in the plasma, the resulting p-WC_x NWs are provided with porous nano-structures and an appropriate carbon coating layer. They exhibit excellent HER performance with a small onset potential of 39 mV, η₁₀ (overpotential to drive a current of 10 mA cm⁻²) of 118 mV, and Tafel slope of 55 mV dec⁻¹ in acid solution, and an onset potential of 56 mV, η₁₀ of 122 mV, and Tafel slope of 56 mV dec⁻¹ in alkaline solution. These performances are superior to those reported for W-based carbide electrocatalysts to date. Impressively, the p-WC_x NWs/CC electrode could sustain more than 40 h of hydrogen production at the current density of 20 mA cm⁻² without observable deterioration in both strong acid and alkaline solutions.