Electrodeposition and characterization of nanostructured composite Ni–W alloys for hydrogen evolution in basic media

The development of efficient, low-cost, and stable electrocatalysts is essential for hydrogen production <i>via</i> water splitting, which is a key technology for sustainable energy. This study investigates electrodeposited nanostructured composite Ni-W alloy thin films with varying tungsten contents (up to 35.8 wt%) as electrocatalysts for the hydrogen evolution reaction (HER) in a 1 mol L^-1 KOH solution. The physical and chemical properties of the electrocatalytic composite coatings were thoroughly characterized using XRD, SEM, EDX and XPS. XRD confirmed their nanocrystalline structure and the presence of Ni₁₇W₃, metallic W, and WO₃ phases. Scanning electron microscopy revealed that increasing tungsten content resulted in smaller particle sizes (from 23.9 nm for pure Ni to 7.3 nm for the highest W-content alloy) and a distinctive wrinkled surface morphology. The electrocatalytic performance for HER was evaluated using linear sweep voltammetry (LSV), Tafel plots, chronopotentiometry, and electrochemical impedance spectroscopy (EIS). These electrochemical analyses consistently demonstrated the incorporation of tungsten significantly enhanced HER activity of the Ni-W, and coating with the highest W-content (35.8 wt%) shows the best performance, characterized by the highest exchange current density (0.644 mA cm^-2) and the lowest Tafel slope (-168 mV dec^-1). Chronopotentiometry of the best catalyst (Ni-6W) proved that it sustains activity after 250 cycles, highlighting superior performance at a current density of -50 mA cm^-2, and EIS confirmed its suitability in the alkaline electrolyte. These results underscore the potential of nanostructured composite Ni-W alloys as promising low-cost electrocatalysts for efficient hydrogen production. This work confirms the general feasibility and potential of composite Ni-W alloys as good electrocatalysts for HER.