Unveiling the origin of high catalytic activity of WO3/MWCNT nanocomposites for the hydrogen evolution reaction

Abstract

The electrocatalytic performance of the hydrogen evolution reaction (HER) largely relies on lower Tafel slope and overpotential values. WO₃-based composites have emerged as one of the most promising electrocatalysts for the HER. Here, we report a facile two-step synthesis method for WO₃ and multi-walled carbon nanotube (MWCNT) composites with variable content of MWCNTs. The optimal integration of MWCNTs with oxygen vacancy-enriched WO₃ provides abundant active sites and better conductivity beneficial for the HER. The analysis reveals that the HER follows a Volmer and Heyrovsky reaction process. Composite formation and the presence of oxygen vacancies in WO₃ were confirmed through various characterization techniques. The optimized composite exhibited the lowest overpotential (η₁₀ = 0.2 V) and Tafel slope (70 mV dec⁻¹ and 85 mV dec⁻¹, before and after performing the stability test). This work provides a valuable insight into the understanding of the structure–HER activity relationship in WO₃/MWCNT composite-based electrocatalysts.