Amorphous Cu–W Alloys as Stable and Efficient Electrocatalysts for Hydrogen Evolution

Cu and W are completely immiscible in equilibrium conditions, and neither of them is a good catalytic element for the electrochemical hydrogen evolution reaction (HER) due to their hydrogen adsorption Gibbs free energy (ΔGH) being too positive or negative, respectively. However, the combination of Cu with W could potentially result in a moderate ΔGH. In this study, a series of binary amorphous Cu–W alloys are fabricated via a magnetron sputtering method. The optimal HER catalytic performance is demonstrated when the nominal component is Cu50W50, showing an overpotential of only 65 mV at 10 mA cm–2 in 1 M KOH. Accordingly, density functional theory calculations show that the amorphous Cu50W50 alloy has a close-to-zero ΔGH compared to the pure Cu and W metals, accounting for its HER activity. In addition, the amorphous Cu50W50 alloy shows no obvious degradation at 100 mA cm–2 for 200 h, highlighting its long-term durability. This work provides a versatile strategy for the preparation of amorphous alloys with completely immiscible components and insights into the compositional design of nonprecious metal electrocatalysts for widespread applications.