Imaging charge carrier transfer in facet-dependent semiconductor photocatalysts by single-particle fluorescence spectroscopy

Facet-dependent semiconductor photocatalysts exhibit immense potential in solar energy conversion and environmental purification. Variations in composition, morphology, atomic arrangement, and surface defects among different nanomaterials result in significant diversities in photocatalytic activities. Nevertheless, the structural diversity covered by integrity and uniformity is detrimental to highlighting the relationship between material and activity, compromising the logical design and optimization of photocatalysts. Fortunately, the "temporally-spatially" resolved single-particle fluorescence spectroscopy imaging technique paves the way for an in-depth exploration of facet-dependent carrier separation and transfer processes at different sites of single nanoparticle, thus providing a profound understanding of the photocatalytic reaction mechanism. In this review, we briefly introduce the imaging principle of single-particle fluorescence spectroscopy. Subsequently, we focus on the recent advancements in single-particle fluorescence spectroscopy technology to characterize the structural complexity and heterogeneity of facet-dependent semiconductor photocatalysts, as well as its application in revealing the interfacial interactions between catalysts and reactants. Finally, we provide outlooks on the development prospects of single-particle fluorescence spectroscopy in the field of photocatalysis.