Preparation of Highly Ordered TiO2 Nanotube Array Photoelectrode for the Photoelectrocatalytic Degradation of Methyl Blue: Activity and Mechanism Study

In this study, highly ordered TiO2 nano-tube arrays (TiO2 NTAs) photoelectrodes were prepared through anodization in the presence of glycerol. The resulting samples were characterized by SEM, XRD, UV-vis DRS and PL spectra. All results showed that TiO2 NTAs samples annealed at 773 K exhibited the highest photocatalytic (PC) activity for the degradation of methyl blue (MB). In addition, the roles of MB on the enhancement of photoelectrocatalytic (PEC) properties of TiO2 NTAs photoanode were investigated through photocurrent response and photoconversion efficiency. As a result, optimized TiO2 NTAs photoanode exhibited high photoinduced current of 0.48 mA.cm(-2), photoconversion efficiency of 0.28% and PEC efficiency of 83% with the existing of MB as sacrificial agent and probe molecules. The high PC and PEC activities could mainly be attributed to the intense light absorption, high separation efficiency of photoinduced charge carriers. Moreover, the contribution of different reactive species on the degradation of MB solution was distinguished in detail. Furthermore, the enhanced visible light PC mechanism was proposed.