Proton-coupled electron transfer (PCET) reactions play a vital role in a wide range of energy conversion processes. A general theory of PCET that includes the quantum mechanical effects of the active electrons and transferring proton, as well as the motions of the proton donor-acceptor mode and solvent or protein environment, has been developed. This formulation enables the calculation of rate constants and kinetic isotope effects for comparison to experiment. This theory has also been extended to describe PCET at interfaces. Recent experiments from Jim Mayer’s group have shown that photoreduced ZnO nanocrystals react by PCET with organic hydrogen atom acceptors such as the nitroxyl radical TEMPO. Application of this PCET theory to these systems indicates that the electron transfers from the conduction band of the ZnO nanocrystal to TEMPO concertedly with proton transfer from a surface oxygen of the ZnO nanocrystal to the oxygen of TEMPO. Moreover, proton diffusion from inside the nanocrystal to reactive sites on the surface was found to explain the experimentally observed nonexponential kinetics. The feedback between experiment and theory was critical to these studies.  This PCET theory has also been used to describe proton transfer from solution to the surface of a gold electrode. All of these theoretical studies are assisting in the interpretation of experimental data and the design of more effective catalysts for energy conversion processes.

Interfacial proton-coupled electron transfer: Interplay between experiment and theory

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.