Exploration of ultrafast dynamic processes in photocatalysis: Advances and challenges

Photocatalysis plays a crucial role in harnessing renewable energy by efficiently converting solar energy into chemical energy. Adequate cognition of photogenerated charge carrier dynamics in photocatalysis is the key to realizing efficient solar energy utilization, and provides guidance for breaking through the efficiency bottleneck. However, a convincing correlation between those photophysical processes and the photocatalytic performance has yet been established due to the complexity of photocatalytic reactions. In this review, we overviewed the detailed ultrafast photophysics in photocatalysis based on three typical ultrafast spectroscopic techniques (TRPL, TA and TRIR), and put a special focus on the justification as well as the limitation on correlating those photophysics with the actual catalytic performance. The classification of carrier behaviors after photoexcitation as well as typical time-resolved spectroscopic characterization techniques are briefly introduced first. State-of-the-art studies on the excited state dynamics in photocatalysis and its correlation to catalytic performance are then systematically presented from three types of common photocatalysts including quantum dots, polymeric photocatalysts, and traditional semiconductors. Finally, a summary on the correlation between ultrafast photophysics and the final photocatalytic performance is provided, and challenges and limitations of current photophysical characterization to rationalize the catalytic performance are outlined.