Carbon-Embedded Tungsten Carbide Electrocatalysts Derived from Self-Deposited Tungsten Oxide for the pH-Universal Hydrogen Evolution Reaction

Tungsten carbide (WC) has been explored as a cost-effective and Earth-abundant alternative electrocatalyst for the hydrogen evolution reaction (HER) in both acid and alkaline conditions, due to its electronic structure comparable to that of platinum. Herein, we report on a simple and convenient approach for depositing the carbon-embedded WC electrocatalyst on nickel foam from the thermal reduction of a sucrose-impregnated self-deposited tungsten trioxide (WO3) precursor. Different sucrose concentrations (between 20 and 80% aqueous solution) and reduction temperatures (between 600 and 1000 °C) are tested to achieve an optimized material exhibiting the best electrocatalytic efficiency for HER. The optimized material is obtained from the precursor impregnated with 50% sucrose and thermally reduced at 800 °C. It can operate HER with overpotential values measured at 10 and 100 mA cm–2 of 0.124 and 0.232 V, respectively, at pH 14, and 0.208 and 0.333 V at pH 0.3, respectively. Furthermore, these electrodes are found to be stable in both media during controlled-current density electrolysis tests over a period of 40 h. The presence of excess amorphous carbon embedding WC is beneficial to improve the conductivity and dispersibility of the electrocatalyst and consequently its HER activity. These findings demonstrate that robust and efficient WC-based binder-free HER electrocatalysts can be produced easily from spontaneously deposited WO3 film and sucrose as the carbon source.