Photoelectrocatalytic Degradation of Tetracycline Through C3N5/TiO2 Nanotube Arrays Photoanode under Visible Light: Performance, DFT Calculation and Mechanism

TiO2 nanotube arrays (TNAs) has been widely applied as a photoanode to improve the chemical stability of electrodes in the photoelectrocatalytic (PEC) system, whereas the practical application of TNAs in organic pollutant degradation is restricted due to low visible-light response and high recombination efficiency of photoinduced carriers. In the present work, the nitrogen-rich carbon nitride (C3N5) modified TNAs (C3N5/TNAs) photoanode was constructed for tetracycline (TC) degradation in the PEC system under visible light. The introduction of C3N5 promoted the photoconversion efficiency and improved the photocatalytic performance by reducing the recombination efficiency of photoinduced carriers. The radical capture experiments verified that •OH and holes were the predominant reactive species, while 1O2, •O2- and electron participated in TC degradation in the PEC system. The density functional theory calculations and HPLC-MS spectra revealed the possible degradation pathway of TC. The toxicity estimation indicated that the overall toxicities of TC were diminished after degradation in PEC system.