Ultrathin Template Approach to Synthesize High-Entropy Intermetallic Nanoparticles for Hydrogen Evolution Reaction

Intermetallic nanoparticles (i-NPs) have received considerable attention as high-performance catalysts for diverse catalytic applications. However, high-entropy i-NPs have been rarely reported due to particle growth and phase separation in the multicomponent alloy. In this study, for the first time, an integrated approach of template and structure transformation is introduced to synthesize a series of sub ≈ 5 nm multicomponent i-NPs with varying compositions. Firstly, ultrathin PtCu nanosheets (NSs) are directly converted into bimetallic PtCu i-NPs. Furthermore, these PtCu NSs are also used as templates for epitaxial growth of the other metals, followed by annealing to obtain high-loading, novel compositions and uniform i-NPs with ternary, quaternary, and quinary compositions, including high-entropy i-NPs. Interestingly, L1₀ intermetallic phases are obtained when Fe is introduced. As a proof-of-concept application, these high-entropy i-NPs showed superior catalytic performance for the hydrogen evolution reaction, which can be attributed to the negatively shifted d-band center of Pt, thereby resulting in reduced H* adsorption energy at Pt sites as supported by density functional theory calculations. Overall, this research presents a promising method for the development of i-NPs with various compositions.