Single-molecule interfacial electron transfer dynamics of porphyrin on TiO2 nanoparticles: dissecting the interfacial electric field and electron accepting state density dependent dynamics

Abstract

Single-molecule photon-stamping spectroscopy correlated with electrochemical techniques was used to dissect complex interfacial electron transfer (ET) dynamics by probing an m-ZnTCPP molecule anchored to a TiO₂ NP surface while electrochemically controlling the energetically-accessible surface states of TiO₂ NPs. Application of negative potential increases the electron density in TiO₂ NPs, resulting in hindered forward ET and enhanced backward ET due to the changes in the interfacial electric field and the occupancy of acceptor states.