Intermediate spillover-enabled cooperation in single-atom catalysts

The linear scaling relationships between multiple intermediates constrain catalytic performance, especially in single-atom catalysts (SACs) with isolated sites. This review focuses on overcoming this limitation by constructing SACs-based cooperative systems that exploit the directional spillover of key intermediates between functionally distinct sites. We systematically summarize how hydrogen-, oxygen-, carbon-, and nitrogen intermediates spillover between four representative cooperation paradigms, including multi-center SACs, SACs-nanoparticle hybrids, SACs-support interaction, and single-atom alloys. Through functional decoupling and site-to-site relay, these strategies reduce kinetic barriers of rate-determining steps and reconstruct reaction pathways. Beyond mitigating activity-selectivity-stability trade-offs of SACs, intermediate spillover mechanism moves catalyst design from trial-and-error approaches toward mechanism-guided engineering.