Abstract :
Using water-coverage-controlled steady and transient infrared absorption spectroscopy and large-model ab initio calculations, it is clarified that water enhances hole trapping at the surface of TiO2 nanospheres but not of well-faceted nanoparticles. This water-assisted effect unique to the nanospheres originates from water adsorption as a ligand at a low-coordinated TiuOH site or through robust hydrogen bonding directly to the terminal OH at the highly curved nanosphere surface.This morphology-dependent water-assisted effect provides a novel and rational basis for designing and engineering nanophotocatalyst morphology to improve photocatalytic performances.