Essential Roles of Proton Transfer in Photocatalytic Redox Reactions

Nowadays, semiconductor-based heterogeneous photocatalysis is receiving much more attention than ever before owing to the increasing challenge of environmental pollution and worldwide demand for clean energy. The stoichiometry of the photocatalytic reactions usually includes the simultaneous gain or loss of electrons and protons. However, not enough emphasis has been placed on the effect of proton transfer on the photocatalytic reactions, particularly on the kinetics of interfacial redox steps. In this article, we highlight the effects of proton on the interfacial electron transfer during the photocatalytic redox reactions. We try to emphasize that the proton transfer can largely determine the energetic profile and reaction pathway by participating in the interfacial redox reactions. Better understanding on the roles and the detailed mechanisms of proton transfer in the photocatalytic surface reactions is required for the further improvement of photocatalytic efficiency.