Effect of synthesis pathway on HER performance of tungsten carbide compared to commercial WC

The relationship between synthesis strategy and electrocatalytic performance plays an important role in the rational design of non-noble metal catalysts for the hydrogen evolution reaction (HER). Herein, tungsten carbide (S-WC) was synthesized via a facile ammonia-assisted route, and its electrocatalytic activity was systematically benchmarked against commercially available tungsten carbide (C-WC). Electrochemical measurements revealed that S-WC achieved a current density of 0.5 mA cm −2 at overpotentials of 297 mV in 1 M KOH and 340 mV in 0.5 M H 2 SO 4 , demonstrating superior HER activity compared with C-WC under identical operating conditions. The corresponding Tafel slopes of 128 and 140 mV dec –1 suggest that the HER kinetics in both alkaline and acidic media are governed predominantly by a Volmer step-limited pathway. Furthermore, the higher exchange current density obtained for S-WC indicates more favourable interfacial charge-transfer kinetics than those of C-WC. The improved performance is attributed to the ammonia-assisted synthesis route, which modifies the surface characteristics of tungsten carbide and increases the density of electrochemically accessible active sites, thereby facilitating faster interfacial charge transfer. Overall, this work demonstrates how synthesis strategy governs the structure–property relationship in tungsten carbide catalysts and provides insight into the rational design of efficient, pH-universal HER electrocatalysts.