Photoeletrocatalytic Degradation Of Ibuprofen And Hydrogen Evolution Simultaneously Using Cu₂O/TiO₂ Nanotube Array Heterojunction Electrode

Photoelectrochemical（PEC） method is the combination of electrochemical and photocatalysis technique. In the PEC system, solar energy can be converted into electrical energy and chemical energy using the photocatalytic materials as electrodes. Photoexcited electrons and holes can precede oxidation and reduction reaction in the anodic and cathodic chamber, respectively. Hence, PEC method is an environment-friendly technique, which can solve the problems of water pollution and energy pinch. TiO₂ is considered to be one of the most potential applications as a photocatalyst. Coupling with narrow bandgap semiconductors to construct heterostructure is an effective way to improve photocatalytic activity of TiO₂.TiO₂ nanotubes arrays（TNAs） were prepared by anodization process. Cu₂O modified TiO₂ nanotube arrays（Cu₂O/TNAs） were synthesized through a square wave voltammetry electrochemical deposition method（SWVE）. To investigate the surface morphological structure, crystalline, chemical composition, optical properties, the prepared samples were characterized by field-emission scanning electron microscopy（FESEM）, X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS） and UV-vis spectroscopy. Moreover, the PEC characteristics of Cu₂O/TNAs were studied through PEC measurement techniques and the experiment of photoeletrocatalytic degradation of ibuprofen and hydrogen evolution simultaneously. At last, electron spin resonance（ESR） analysis was conducted to help clarify the PEC reaction mechanism. FESEM images showed that Cu₂O nanoparticles with flower-like and octahedral structure were deposited on TNAs. XRD results show that Cu₂O/TNAs phase is anatase and with a high crystallinity. XRD and XPS spectras proved the existence of Cu₂O, rather than Cu or CuO. The UV-vis results indicated the absorption edges of Cu₂O/TNAs shifted to visible light region. Compared to pure TNAs, Cu₂O/TNAs exhibited higher photocurrent density under Hg lamp irradiation. The highest photocurrent density achieved 4.04 mA/cm2 with applying 0.5 V bias potential. In addition, electrochemical impedance spectroscopy（EIS） measurements revealed that the recombination of photogenerated electron-hole pairs was inhibited and electron lifetime was extended effectively by doping Cu₂O. Cu₂O/TNAs performed better than TNAs in the experiment of photoeletrocatalytic degradation of ibuprofen and hydrogen evolution simultaneously. ESR analysis proved the existence of ?OH radical in the TNAs and Cu₂O/TNAs PEC system.In conclusion, the PEC system may have an excellent applicable prospect in PEC degradation of organic pollutants and hydrogen generation concurrently, and this study in hope to provide valuable reference for the future studies about PEC reaction mechanism.