High-entropy alloy nanocrystal assembled by nanosheets with d–d electron interaction for hydrogen evolution reaction

Abstract

The development of efficient catalysts with superior performance for water splitting into hydrogen is urgently required in the catalysis community. Herein, for the first time, we report unique high-entropy alloy (HEA) catalysts– PtMoPdRhNi nanocrystals (NCs) with strong d–d electron interaction encapsulated with radial nanosheets. Through the exploration of the atomic ratio of PtMoPdRhNi, the obtained Pt₂₈Mo₆Pd₂₈Rh₂₇Ni₁₅ NCs with the strongest d–d electron interaction display the highest alkaline hydrogen evolution reaction (HER) activity, with the overpotential as low as 9.7 mV at a current density of −10 mA cm⁻². The superior HER performance mainly originated from the d–d electron interaction in constituent metals and multi-active sites with optimized energy barriers of HEAs. In situ surface-enhanced Raman spectroscopy (SERS) and theoretical calculations are combined to reveal the mechanism in both water dissociation and H* adsorption/desorption. This study not only elucidates the complex structural information and the catalytic mechanisms of multielement HEA systems in depth for further rational design of efficient catalysts but also highlights HEAs as sufficiently advanced catalysts and accelerates the research of HEAs in energy-related applications.