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

Achieving the efficient construction and regulation of active sites in complex high-entropy system is crucial for developing high-entropy alloys (HEAs) as top-notch catalysts for hydrogen evolution reaction (HER). Herein, a rapid thermal shock process coupled with Cr content regulation was employed to fabricate a self-supporting PtFeCoNiCuCr0.5@CC-720 as HEAs material, which bears 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 microstructure as well as HER electrocatalytic activity was elucidated. It was revealed that incorporation of Cr enhances the crystallinity of HEAs 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 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 in high entropy alloys and is helpful for designing electrocatalysts with enhanced activity.