Spectroelectrochemical photoluminescence (SEPL) is used to investigate surface electron and hole traps on anatase
nanoparticles, anatase nanosheets and rutile nanowires in aqueous and nonaqueous environments. In aqueous
environment there is an overvoltage for occupying surface electron traps in rutile and anatase samples. For anatase,
this overvoltage is larger on (101) nanoparticles than on (001) nanosheets. The electrochemical energy levels of
electron traps determined by SEPL in acetonitrile are consistent with emitted photon energies as determined by the
photoluminescence spectrum. Our results show how the contacting solvent and particle morphology can influence
the redox potential of surface electron traps and thus guide further research on improving the performance of nano-
TiO<sub>2</sub> in applications such as dye–sensitized solar cells and solar water splitting.