Multi-Component Intermetallic Nanocrystals: a Promising Frontier in Advanced Electrocatalysis

As the latest representation of high-entropy materials, structurally ordered multi-component intermetallic (MCI) nanocrystals exhibit various attractive functional properties, exceptionally high activity, and durability in energy-related electrocatalytic applications. These properties are primarily attributed to their ordered superlattice structures and high-entropy effects in one sublattice. However, to date, MCI nanocrystals have not been systematically studied. This review comprehensively analyzes the structural characteristics of MCI nanocrystals and the thermodynamics and kinetics of their ordering transformation. Various synthesis strategies for constructing MCI nanocrystals are discussed, including traditional thermal annealing, the cutting-edge manufacturing protocol of Joule heating methods, and wet chemical synthesis, highlighting their advantages and limitations. Importantly, the electronic structure characteristics of MCI nanocrystals are analyzed, beginning with the orbital hybridization of platinum group elements with 3d-block, p-block, and f-block metals, and further discussing their roles in electrocatalytic reactions (oxygen reduction reaction, hydrogen evolution reaction, formic acid oxidation reaction, and methanol oxidation reaction). The focus is on how the optimized electronic structure of active sites in MCI nanocrystals and the shifting of the d-band center contribute to performance enhancement. Based on comprehensive analysis, this review summarizes the progress made in MCI nanocrystals to date and highlights the significant challenges faced by the scientific community.