Spatial Charge Separation in Photocatalysis: From Particle Adjacency to Atom Proximity

Abstract Charge separation is one of the basic processes in artificial photosynthesis, which plays a key role in determining the solar energy conversion efficiency. Utilizing charge separation forces to drive the spatial separation of photogenerated electrons and holes has been demonstrated as an effective approach to improve the charge separation efficiency. Herein, a comprehensive review is presented on the latest advances in spatial charge separation strategies for artificial photosynthesis, ranging from the macroscopic particulate scale to the microscopic atomic scale. The fundamental driving forces for the spatial photocharge separation in semiconductor photocatalysts are first outlined. Then, the key characterization techniques to demonstrate spatial charge separation are introduced. Subsequently, the photocatalysis systems featuring spatial charge separation between interparticles, junction interfaces, crystal facets, molecular motifs, and neighboring surface atoms are introduced. The underlying mechanisms of spatial charge separation at different scales corresponding to these photocatalysis systems are also analyzed. Finally, this review concludes with remarks on the advantages and drawbacks of these interparticle and intraparticle charge separation approaches. This review is anticipated to offer helpful insights into the underlying mechanisms of spatial charge separation at different scales and to provide guidance for the precise design of photocatalyst surfaces and structures.