Single-atom heterogeneous photocatalysts

Developing highly efficient photocatalysts with low production costs is critical to practical applications. Single-atom photocatalysts (SAPs), in which isolated atoms are anchored on the semiconductor supports, have attracted considerable attention owing to their preeminent catalytic activity, superior selectivity, impressive stability, and maximum atom utilization efficiency. Moreover, they offer a great opportunity to explore photocatalysis on the atomic level. Single atoms stand out from bulk, nanoparticle, and nanocluster counterparts. Herein, we summarize their recent progress, mainly focusing on their properties, geometric structures, synthetic strategies, characterization techniques, and photocatalytic applications. Also, the functions of isolated metal atoms in photocatalytic reactions are discussed. Finally, the challenges and perspectives of designing and fabricating highly active SAPs are presented.