N-Carbon coated P-W2C composite as efficient electrocatalyst for hydrogen evolution reactions over the whole pH range

Abstract

Development of a highly efficient and stable hydrogen evolution reaction (HER) electrocatalyst based on non-precious-metal remains a great challenge. Herein, we report P-modified tungsten carbide encapsulated in N-doped carbon (P-W₂C@NC) as an efficient and stable HER electrocatalyst over the whole pH range (0–14), prepared by annealing polyoxometalate (H₃PW₁₂O₄₀·xH₂O) and dicyandiamide at a high temperature. To achieve a current density of 10 mA cm⁻², P-W₂C@NC required an overpotential of 89 mV in acid, 63 mV in alkaline solution and 185 mV in neutral solution. This is the first case of a tungsten-carbide-based HER electrocatalyst operating at all pH values with high activity and stability, and might provide some new routes for the exploration of tungsten-based Pt-like electrocatalysts for the HER.