Enhanced solar water-splitting performance of TiO2 nanotube arrays by annealing and quenching

- With fast cooling rate, the anatase-to-rutile transformation is abated when the TiO2 is annealed at high temperature.
- The thickness of the barrier layer underneath the nanotubes decreased with faster cooling rate.
- C doping enhanced the visible light absorption effectively.
- A high solar conversion efficiency of 1.75% is obtained for the TiO2 nanotubes annealed at 650 °C with oil quenching.