Effect of Post-Annealing Treatment on Photocatalytic and Photoelectrocatalytic Performances of TiO2 Nanotube Arrays Photoelectrode

Highly ordered TiO2 nano-tube arrays (TNTAs) photoelectrodes were prepared through anodization method, followed by annealing treatment. Morphologies and structures of the as-prepared TNTAs samples were investigated through scanning electron microscopy (SEM) and X-ray diffraction (XRD). In addition, the optical and photoelectrochemical (PECH) properties were investigated through ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) and transient photocurrent response. Furthermore, the photodecomposition performances were investigated through the yield of hydroxyl (center dot OH) radicals and photocatalytic (PC) degradation of RhB under Xenon light irradiation. Results indicated that the TNTAs samples annealed at 723 K exhibited the highest photocurrent response, PC performance and yield of center dot OH radicals, in which 60.8% of RhB could be degraded by PC degradation within 60 min. The high PC performance could mainly be attributed to the anatase structure, high crystallinity and highly ordered nano-tubular structure, which favored the transfer and separation of photoinduced charge carriers. This study suggests that highly ordered nano-structure could provide superior pathway for the charge transfer and separation.