Enabling Cr-induced efficient hydrogen evolution on high-entropy alloys via rapid thermal shock

Abstract

Achieving efficient construction and regulation of active sites in complex high-entropy systems is crucial for developing high-entropy alloys (HEAs) as top-notch catalysts for the hydrogen evolution reaction (HER). Herein, a rapid thermal shock process coupled with Cr content regulation was employed to fabricate a self-supporting PtFeCoNiCuCr_0.5@CC-720 HEA material, which exhibits a low HER overpotential of 83 mV to achieve 100 mA cm⁻² in KOH electrolyte. Based on experiments and density functional theory (DFT) calculations, the influence of Cr content on the microstructure as well as HER electrocatalytic activity was elucidated. It was revealed that incorporation of Cr enhances the crystallinity of the HEA material, accelerates the electron transfer rate, and modulates the electronic configuration of active sites due to its low electronegativity induced electron-donating effect. As a result, the d-band center of Pt sites was shifted towards the Fermi level, leading to optimized Gibbs free energy for hydrogen species adsorption/desorption and improved HER activity. This work offers a perspective for rapid regulation of HER activity on high entropy alloys and is helpful for designing electrocatalysts with enhanced activity.