Surface polaron states on single-crystal rutile TiO2 nanorods array enhancing charge separation and transfer

Polaron states on TiO2 photoanode are an important electron transfer pathway at the electrode-electrolyte interface. Here, we electrochemically doped the single-crystal rutile TiO2 nanorods array with exposed (110) facet to produce surface polaron states, Ti3+-OH, greatly contributing to the charge separation and transfer. Our results experimentally clarified the previous confusing understanding in the origination of the improved photoelectrochemical (PEC) water splitting and verified the enhanced PEC effects mainly from surface polaron states instead of the grain boundaries passivation.