Redefining Catalytic Boundaries: Precise Design and Engineering of Nanoscale Partnerships in Nanoparticle-Regulated Single-Atom Catalysts for Multifunctional Applications

During the synthesis of single-atom catalysts (SACs), the high surface free energy often leads to spontaneous aggregation, resulting in the generation of nanoparticles (NPs), which are regarded as undesirable bystanders that reduce the dispersion of SACs. However, as research evolved, the importance of structural heterogeneity in SACs became evident, so that the stability, reactivity, and selectivity of SACs are no longer limited to the design of single active sites. This realization has driven the emergence of catalysts in which NPs and SACs coexist (NPs-SACs), overcoming the limitations of traditional SACs and combining the atomic efficiency of SACs with the versatile catalytic properties of NPs. In view of this subversive cognition, this work summarizes the synthesis method of NPs-SACs from the underlying design, focusing on the precise ratio control and interconversion of NPs and SACs, and points out the possible risk of false positives in identifying NPs-SACs. The impact of NPs on the catalytic activity of SACs, including their role in modifying physicochemical properties, and geometric and electronic structures and the mechanism of enhancing reactivity through various specific interactions, is discussed. Additionally, recent breakthroughs in NPs-SACs across diverse fields are reviewed. Finally, the limitations of current research and future avenues are outlined to guide the design of next-generation catalysts.