A Multi-Site Synergistic Effect in High-Entropy Alloy for Efficient Hydrogen Evolution

Unraveling the mechanism driven by electronegativity-dominated electronic configuration is crucial for developing high-entropy alloys as efficient catalyst for hydrogen evolution reaction (HER). In this work, different atoms with diverse electronegativities are explored to regulate the electrocatalytic activity of PtFeCoNi@HCS toward HER, resulting in PtFeCoNiCuCr@HCS with an overpotential of 29 mV at 10 mA cm(-2) and enhanced durability surpassing that of commercial 20% Pt/C in KOH environment. Based on various physicochemical and electrochemical techniques as well as density functional theory calculations, a multi-site synergistic effect within PtFeCoNiCuCr@HCS material is elucidated in terms of both structural composition and electrocatalytic process. Briefly, Pt and Cu serve as the fundamental elements to form face-centered cubic crystal framework, Cr primarily functions as an electron donor to regulate the electronic configuration, Co serves as the main active site for water dissociation, and the produced hydrogen species prefer to transfer toward Pt, Fe, and Cu sites for hydrogen formation. This work offers an in-depth insight on the synergistic mechanism in high entropy alloys and is helpful for designing efficient electrocatalysts.