Electrocatalytic performance of high-entropy alloys in alkaline hydrogen evolution reaction with high electronegativity difference

Abstract

High-entropy alloys (HEAs) are emerging electrocatalysts, which can convert inert Cu into a highly active electrocatalytic site by controlling the electronic structure of Cu through electronegativity differences after alloying. A multi-component Fe_0.19Co_0.23Ni_0.28Cu_0.28Cr_0.02 HEA thin film catalyst was prepared on the surface of a copper substrate by electrodeposition, and a low overpotential of 229 mV (η₅₀) was achieved, which was close to 207 mV of a Pt/C electrode. The Tafel slope was 34.1 mV dec⁻¹, which was slightly lower than that of the Pt/C electrode at 35 mV dec⁻¹, indicating excellent reaction kinetics. The catalyst exhibited remarkable in alkaline solution, after 10 h of Open Circuit Potential (OCP) testing; at 3000 s, the OCP started to stabilize at a value of −0.3 V and then remained stable until 36 000 s. Density functional theory (DFT) calculations show that the Cu site had the lowest water dissociation energy barrier and the lowest H* adsorption energy (0.009 eV). This study compares the volcanic-type relationships among precious metals, transition metals, and the work in this paper through experimental tests and simulation calculations, highlighting the excellent hydrogen evolution reaction performance of HEAs. Furthermore, it establishes trends between the intrinsic properties of materials and the rates of catalytic reactions, providing theoretical guidance for the design and activity prediction of efficient catalysts.