Single Atoms–Metal Clusters/Nanoparticles Synergistic Dual‐Site Electrocatalysts for Alkaline Hydrogen Evolution

ABSTRACT

Now a new generation of electrocatalysts featuring the coexistence of single atoms (SAs) and metal clusters/nanoparticles (CLs/NPs) are exhibiting remarkable synergistic effects for alkaline hydrogen evolution reaction (HER). The distinct chemical environments of SAs and CLs/NPs allow for the spatial separation of different reaction steps, boosting alkaline HER synergistically. This review provides a comprehensive account of the advanced SAs‐CLs/NPs synergistic electrocatalysts for alkaline HER and anion exchange membrane water electrolysis (AEMWE). We classify these catalysts into four types based on the elemental composition of the active sites and discuss their respective synthetic approaches, with an emphasis on strategies to control the relative loading and spatial proximity of SAs and CLs/NPs. We then present a detailed mechanistic discussion of how synergistic interactions between SAs and CLs/NPs accelerate alkaline HER kinetics, drawing on insights from in situ/operando spectral characterization techniques and density functional theory (DFT) calculations. The performance of these catalysts in AEMWE devices is also evaluated, highlighting the most promising systems for practical application. Finally, we outline the key challenges that must be overcome to realize the full potential of SAs‐CLs/NPs synergistic catalysts.