TiO2 nanotubes with ultrathin walls for enhanced water splitting.

We demonstrate, for the first time, the synthesis of titania nanotubes with ultrathin (3-5 nm) wall thickness. As revealed by the incident photon-to-current collection efficiency (IPCE) and electrochemical impedance spectroscopy measurements, the ultrathin walls, less than the charge carrier diffusion length, were essential to ensure fast and efficient charge carrier collection.