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 (Delta G H) being too positive or negative, respectively. However, the combination of Cu with W could potentially result in a moderate Delta G H. 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 Delta G H 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.