Strain engineering of high-entropy alloy catalysts for electrocatalytic water splitting.

Developing active and cost-effective bifunctional electrocatalysts for overall water splitting is challenging but mandatory for renewable energy technologies. We report a high-entropy alloy (HEA) of PtIrCuNiCr as a bifunctional electrocatalyst for overall water splitting, which shows a low overpotential of ca. 190 mV at the current density of 10 mA cm. Compared with pure metals, HEAs exhibit remarkable surface strain due to severe lattice distortion in their crystal structures. Theoretical calculations reveal that the strain can regulate the binding energy of intermediates on catalysts by adjusting the metal-metal bonding energy. It pushes the HEA toward the top of volcano plots to achieve superior electrocatalytic activity for both hydrogen and oxygen evolution reactions. The strain effect of HEAs on electrocatalysis can be well engineered by tuning the catalyst radius or configurational entropy. This work renders a systematic strain regulation strategy for designing a high-performance HEA catalyst for overall water splitting.