Tuning the Ultrafast Dynamics of Photoinduced Proton-Coupled Electron Transfer in Energy Conversion Processes

Photoinduced proton-coupled electron transfer (PCET) is essential for a wide range of energy conversion processes in chemical and biological systems. Understanding the underlying principles of photoinduced PCET at a level that allows tuning and control of the ultrafast dynamics is crucial for designing renewable and sustainable energy sources such as artificial photosynthesis devices and photoelectrochemical cells. This Perspective discusses fundamental aspects of photoinduced PCET, including the characterization of different types of excited electronic states, as well as the roles of solute and solvent dynamics, nonadiabatic transitions, proton delocalization, and vibrational relaxation. It also presents strategies for tuning and controlling the charge transfer dynamics and relaxation processes by altering the nature and positions of molecular substituents, the distance associated with electron transfer, the proton transfer interface, and the solvent properties. These insights, in conjunction with further studies, will play an important role in guiding the design of more effective energy conversion devices.