Single-site photocatalysts with a porous structure

A photocatalytic reaction involves charge separation and transfer under photoirradiation, and the photogenerated charge carriers (holes and electrons) are responsible for the photocatalytic activity of the catalyst. The active centres in a single-site photocatalyst are the isolated and spatially separated sites that may interact with reactants after photo-irradiation. Generally, single-site photocatalysts perform better than other types of photocatalysts owing to the presence of the efficient active centres. A porous structure can provide more single sites and special passages for charge transport. Thus, the introduction of a porous structure into a photocatalyst may result in markedly enhanced photocatalytic reactivity, providing a promising strategy for the design and fabrication of novel photocatalysts with high performances. In this review, we summarize the developments in single-site photocatalysts, particularly those with a porous structure, such as metal-incorporated zeolites, metal–organic frameworks and porous semiconductor photocatalysts. The synthesis, structures and catalytic performances of these single-site photocatalysts have been described, and characterization and reaction mechanisms for single-site photocatalysts have also been detailed. Finally, we point out the significance of study on single-site photocatalysts with a porous structure.