From Single Atom Photocatalysts to Synergistic Photocatalysts: Design Principles and Applications

Abstract Photocatalysis represents a solar‐to‐chemical energy transformation process including three processes, light absorption, charge separation/transfer, and surface reactions. Owing to the merits of single‐atom catalysts (SACs) toward maximal atom utilization, unsaturated coordination structure, and tunable electronic configuration, single‐atom photocatalysts (SAPs) exhibit extraordinary photocatalytic performance toward a series of sustainable reactions. Accompanied by the complexity of photocatalytic processes and the realistic demand for tandem reactions as well as the promotion of intricate reactions with multiple reaction routes and intermediates, significant efforts are desired to gain in‐depth insights into the design and fabrication of synergistic photocatalysts. In this review, the first part discusses the design principles from traditional semiconductor‐based photocatalysts to SAPs. Moreover, six basic models of synergistic photocatalysts including remote dual atoms, bridged dual atoms, adjacent dual atoms, single atoms + clusters/nanoparticles (NPs), single atoms + defects, NPs + NPs, are highlighted and distinguished by their structure features. Second, specific examples of SAPs and synergistic photocatalysts are appreciated under the category of CO₂ reduction reaction (CO₂RR), hydrogen evolution reaction (HER), nitrogen reduction reaction (NRR), and pollutants degradation. Finally, this review will conclude by discussing the challenges and future perspectives of SAPs and synergistic photocatalysts for sustainable applications.