Lighting the Path to Practical Applications of Single-Atom Catalysts in Photocatalysis: The Role of Platinum Group Single Atoms in Enhancing Catalytic Activity

Single-atom catalysts (SACs) show promise because of their efficient use of precious metals, unique coordination and electronic structures, and excellent tunability. Photocatalysis can harvest solar energy to drive energetically unfavorable reactions under mild conditions, offering a sustainable alternative to energy-intensive reactions. However, the efficiency of solar photocatalysis is limited by poor solar spectrum utilization and rapid charge recombination. Integrating single atoms into semiconductor photocatalysts is a promising route to address these limitations. Mechanistic understanding of single-atom photocatalysis is crucial for developing efficient catalysts as they guide effective material design. This work provides an overview of the current knowledge on platinum group SACs applied to photocatalytic applications with a focus on the role of single atoms in photocatalytic reactions. The review begins with a summary of the unique advantages of platinum group metal SACs as well as their common structures. A concise summary of synthesis methods is then provided, followed by a comprehensive review of characterization methods for SAC structure, photoelectronic properties, and mechanisms of action. Next, the role of single atoms in improving general photocatalytic processes as well as specific reactions are discussed. Finally, future outlooks for SAC development are included to guide further advancements in the field.