Controllable preparation of mixed-phase TiO2 nanotube arrays for photoelectrochemical H2 evolution coupled with Rhodamine B degradation

The controllable synthesis TiO 2 with desired morphology and phase composition is essential for achieving the properties required in various applications. Herein, TiO 2 nanotube arrays were synthesized through anodic oxidation followed by calcination in an argon atmosphere. The effects of fluoride ion (F - ) concentration in the electrolyte, oxidation time, and calcination temperature on morphology and phase composition were systematically investigated. The optimal conditions for producing well-defined mixed-phase TiO 2 nanotubes were determined to be anodizing at 60 V for 2 h in an electrolyte consisting 0.4 wt% F - . The mixed-phase TiO 2 obtained at 600 °C exhibited the highest photocurrent, which is 2.7 and 3.4 times that of single anatase phase and rutile phase, respectively. The total amount of hydrogen evolution over the optimized mixed-phase TiO 2 photoelectrode reached 387.1 μmol/cm 2 within 160 min under UV–vis illumination at an applied bias of −1.5 V. The corresponding degradation efficiency for RhB (Rhodamine B) at the platinum electrode was approximately 13 %. The enhanced PEC (photoelectrocatalytic) performance of mixed-phase TiO 2 can be attributed to the synergistic effects arising from extended visible-light absorption, a well-defined one-dimensional nanotube structure, and efficient separation of photogenerated carriers at hetero-phase junction. This work provides valuable guidance for synthesizing mixed-phase TiO 2 electrode using controllable methods.