Facile electrodeposition of tungsten trioxide and molybdenum disulfide on carbon cloth for the hydrogen evolution reaction in acidic media

Molybdenum disulfide (MoS 2 ) and tungsten trioxide (WO 3 ) are promising catalysts for the hydrogen evolution reaction (HER), but these materials have limitations. MoS 2 has a relatively low conductivity, whereas WO 3 requires a high onset potential. To address these shortcomings, a WO 3 :MoS x bilayer was formed on carbon cloth via rapid electrodeposition and used as an electrocatalyst for the HER, thereby combining the benefits of both components. By varying the electrodeposition conditions, including the electrochemical window, tungstate concentration, and cycle number, the WO 3 underlayer was optimised to yield a conductive, high-surface-area scaffold that serves as a substrate for nucleation of the MoS x . Uniform WO 3 electrodeposition was achieved, while the electrodeposited MoS x overlayer healed WO 3 cracks and protected the WO 3 underlayer. The optimised CC/WO 3 :MoS x exhibited an overpotential of 160 mV at 10 mA cm –2 and 260 mV at 100 mA cm –2 , and a Tafel slope of 94 mV dec –1 . Good stability over 60 h at a relatively high current density of 30 mA cm –2 was achieved using a thin Nafion over-coating. Only minor surface compositional variations were observed, indicating excellent stability. These findings confirm that electrodeposited WO 3 :MoS x on carbon cloth can serve as a cost-effective, scalable, and efficient HER electrocatalyst in acidic environments.