Ultrafast proton coupled charge transfer dynamics in photocatalysis

In this talk I will present our experimental and theoretical studies on the nature of electron and hole acceptor states and their dynamics for protic solvent molecule (H$_{2}$O, CH$_{3}$OH) covered TiO$_{2}$ surfaces. Electron-hole pair generation by band gap excitation can introduce charges into protic solvent/TiO$_{2}$ interface, which can drive photocatalytic processes. By time resolved two-photon photoemission and DFT electronic structure calculations we identify the partially solvated or ``wet'' electron accepter states, and their proton-coupled electron transfer (PCET) dynamics. Because holes are through to be the primary reagents for photocatalysis on TiO$_{2}$, we also explore possible hole driven PCET dynamic pathways.