Bright “cool” road paint beats city heat, but it can also blind drivers. New research sets the first safety caps on shine—here’s the simple rule planners need before they coat the streets.

Particulate photocatalytic systems using nanoscale photocatalysts have been developed as an attractive promising route for solar energy utilization to achieve resource sustainability and environmental harmony. Dynamic obstacles are considered as the dominant inhibition for attaining satisfactory energy-conversion efficiency. The complexity in light absorption and carrier transfer behaviors has remained to be further clearly illuminated. It is challenging to trace the fast evolution of charge carriers involved in transfer migration and interfacial reactions within a micro–nano-single-particle photocatalyst, which requires spatiotemporal high resolution. In this review, comprehensive dynamic descriptions including irradiation field, carrier separation and transfer, and interfacial reaction processes have been elucidated and discussed. The corresponding mechanisms for revealing dynamic behaviors have been explained. In addition, numerical simulation and modeling methods have been illustrated for the description of the irradiation field. Experimental measurements and spatiotemporal characterizations have been clarified for the reflection of carrier behavior and probing detection of interfacial reactions. The representative applications have been introduced according to the reported advanced research works, and the relationships between mechanistic conclusions from variable spatiotemporal measurements and photocatalytic performance results in the specific photocatalytic reactions have been concluded. This review provides a collective perspective for the full understanding and thorough evaluation of the primary dynamic processes, which would be inspired for the improvement in designing solar-driven energy-conversion systems based on nanoscale particulate photocatalysts.