Compositional engineering of tungsten-based carbides toward electrocatalytic hydrogen evolution

For purpose of developing noble-metal-free electrocatalysts with high activity toward hydrogen evolution reaction (HER), tungsten-cased carbides are synthesized with ammonium metatungstate as tungsten source, resorcinol and formaldehyde as carbon source. Systematic experiments demonstrate that the introduction of iron nitrate complexed with trisodium citrate has a clear impact on the structural and morphological features of final products. Moreover, various crystalline phases involving WC, W₂C, W and Fe₃W₃C can be readily tuned by altering the Fe/W atomic ratio. Electrochemical measurements reveal that the HER activity of Fe₃W₃C is superior to those of other control groups, giving a η₁₀ (the overpotential for driving a current density of 10 mA cm⁻²) of −226 mV and Tafel slope of 91 mV dec⁻¹ in acid solution. Theoretical calculations suggest the improved electrocatalytic performance of Fe₃W₃C may be attributed to the hydrogen spillover from W sites to Fe sites. This work may open up new opportunities to develop high-performance catalysts via accelerating hydrogen adsorption and hydrogen evolution at different components.