Degradation of AO7 through RGO/TiO2 nanotube arrays photoanode in UV/electrical coupling system：performance and mechanism analysis.

In order to improve the disadvantage of the high e−-h+ complexation rate in TiO 2 NTs. In this study, RGO was deposited on TiO 2 NTs using the cyclic deposition method to obtain RGO-TiO 2 NTs photoanode. The physical and chemical properties of the photoanodes were analyzed and applied to the photoelectrocatalytic system for treating AO7 dye. The surface structure and composition analysis results indicated that GO was effectively reduced to RGO and uniformly loaded on the surface of TiO 2 NTs. The performance studies showed that RGO/TiO 2 NTs with 20 cycles exhibited the most favorable optical and photoelectrochemical properties. The forbidden bandwidth of the modified photoanode was reduced from 3.18 to 2.94 eV. Under the synergistic effect of 1.5 V bias voltage and UV light, the photocurrent density of RGO/TiO 2 NTs-20 reached 7.46 mA cm−2, which was approximately 1.32 times of that of pure TiO 2 NTs. In addition, the photoconversion efficiency of the photoanode increased from 3.14 % to 4.48 % after the modification with RGO. The optimal reaction conditions of the photoelectrocatalytic system with RGO/TiO 2 NTs-20 as the photoanode for the treatment of AO7 dyes were electrolyte concentration of 0.1 mol·L−1, pH of 2.7, and stirring speed of 255 r min−1. Under which the degradation rate of AO7 reached 92.97 %, and the rate constant reached 0.01512 min−1. The primary active species involved in the degradation system were h+ and ·OH, with ·O 2 − serving as the secondary active substance. In summary, RGO can be used as an electron conductor to improve the performance of TiO 2 NTs, and the photoelectrocatalytic system with RGO/TiO 2 NTs as the photoanode can effectively treat AO7 dyes. The study offers new ideas for preparing efficient photoelectrodes and applying them in the field of pollutant degradation. • A coupled system of UV and electricity is established. • The e− transfer rate of TiO 2 NTs photoanodes was enhanced by using loaded RGO. • The reaction conditions were optimized for the treatment of AO7 with RGO/TiO 2 NTs as photoanode PEC system. • The mechanism of AO7 treatment by PEC system with RGO/TiO 2 NTs as photoanode was investigated. [ABSTRACT FROM AUTHOR]