Synergistic effects of single atoms and nanoparticles: Emerging opportunities for electrocatalysis

The rational design of high-performance catalysts is crucial for advancing energy conversion and storage technologies. Single-atom and nanoparticle synergistic catalysts (SAC-NPs) have garnered significant attention due to their ability to precisely modulate electronic structures and optimize intermediate adsorption energies. Single-atom catalysts (SACs) exhibit maximized atomic utilization and well-defined active sites; however, their restricted electronic tunability and inherent instability limit their widespread application. Conversely, nanoparticle catalysts (NPs) provide superior charge transfer capabilities and enhanced catalytic stability, effectively complementing SACs. The SAC-NPs leverage atomic-scale electronic interactions to enhance catalytic activity, stability, and reaction kinetics, making it a promising platform for electrocatalysis. Therefore, elucidating the synergistic catalytic mechanisms of SAC-NPs and refining optimization strategies are crucial for advancing the development of high-performance catalysts. This review systematically summarizes the synthesis strategies and structural modulation approaches of SAC-NPs. Furthermore, the synergistic catalytic mechanisms, encompassing electron transfer, tandem catalysis, and bifunctional catalysis, are critically examined from both experimental and theoretical perspectives. Finally, recent advancements in SAC-NPs for key electrocatalytic reactions are reviewed, along with current challenges and future research directions. This work aims to provide comprehensive theoretical and practical guidance for the development of SAC-NPs, facilitating the rational design of next-generation catalysts and advancing renewable energy technologies.