A novel electric-assisted photocatalytic technique using self-doped TiO2 nanotube films

Semiconductor doping is an effective strategy for improving the light absorption efficiency and the photogenerated carrier transport in photocatalysts. However, bulk defects induced by doping act as recombination centers, accelerating the recombination of carriers, which is detrimental to the photocatalytic performance. In this study, a novel electric-assisted photocatalytic technique was developed to reduce the recombination of the carriers trapped by the defects. The technique involves applying a low external voltage to a self-doped TiO2 nanotube film, without any electrolyte and counter electrode. The remarkable improvement in the charge carrier dynamics under the electric assistance is attributed to the significant promotion of photogenerated electron fluxes and prevention of charge recombination. The electric-assisted photocatalytic technique is compatible with a liquid- or a gas-phase reactive system, e.g., water splitting, H2O2 synthesis, and CO2 photoreduction. The technique is sufficiently advanced to allow scale-up of the photocatalytic process from laboratory scale to industrial-scale.