Enhanced photoelectrocatalytic performance for degradation of diclofenac and mechanism with TiO_2 nano-particles decorated TiO_2 nano-tubes arrays photoelectrode

摘要

In this study, TiO_2 nano-particles decorated TiO_2 nano-tubes arrays (TiO_2 NPs/TiO_2 NTAs) photoelectrodes have been successfully prepared through anodization, combined with ultrasonic strategy, followed by annealing post-treatment. The morphology and structure of the as-prepared TiO_2 NPs/TiO_2 NTAs photoelectrodes were characterized by scanning electrons microscopy (SEM), N_2 adsorption/desorption isotherms, X-ray diffraction (XRD) and UV-visible light diffuse reflection spectroscopy (DRS). In addition, the generation of hydroxyl radicals (·OH) was detected by a photoluminescence (PL) spectra using terephthalic acid (TA) as a probe molecule. Furthermore, the photoelectrochemical (PECH) properties of TiO_2 NPs/TiO_2 NTAs photoanode were investigated through transient open circuit potential (OCP), photocurrent response (PCR) and electrochemical impedance spectroscopy (EIS). It was found that TiO_2 NPs/TiO_2 NTAs photoelectrode exhibited a distinct decrease of OCP of -0.219 mV cm~(-2) and PCR of 0.049 mA cm~(-2), while a significantly enhanced photoelectrocatalytic (PEC) efficiency of 63.6% (0.4 V vs. SCE) for the degradation of diclofenac. Moreover, the enhanced PEC mechanism of TiO_2 NPs/TiO_2 NTAs photoanode was proposed. The high PEC performance could be attributed to the decoration of TiO_2 NPs, which could improve the mobility and separation efficiency of photoinduced charge carriers under external potential.