Fabrication of MnO2/TiO2 nano-tube arrays photoelectrode and its enhanced visible light photoelectrocatalytic performance and mechanism

Abstract

Abstract MnO 2 /TiO 2 nano-tube arrays (MnO 2 /TiO 2 NTAs) photoelectrode was synthesized through anodization and electrodeposition, followed by the prepared conditions optimized. Subsequently, structures of the as-prepared photoelectrodes were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Besides, the light absorption capacities and photoelectrochemical (PECH) properties were investigated through UV–vis diffuse reflectance spectrophotometer (UV–vis DRS), photocurrent response (PCR) and electrochemical impedance spectroscopy (EIS). In addition, these photoelectrodes were used for the photoelectrocatalytic (PEC) degradation of methylene orange (MO) under Xenon lamp irradiation. Moreover, the enhanced PEC mechanism was further confirmed through scavengering effect and photoluminsecence (PL) spectra. Results presented that the highly ordered TiO 2 nano-tube arrays photoelectrodes processed a uniform sizes of inner diameter of 300 nm and well thickness of 60 nm with MnO 2 nanoparticles successfully deposited. Furthermore, it was found that these novel MnO 2 /TiO 2 NTAs photoelectrodes could not only red-shift the light absorption to visible region between 400 nm and 700 nm, but also significantly enhance the generation of hydroxyl radicals ( OH) which played an important role in the PEC system. Noticeably, the MnO 2 /TiO 2 NTAs photoelectrodes made in the optimized conditions exhibited much higher PEC activity toward MO degradation with the efficiency up to 95.2% within 1 h when external potential (+2.0 V) was applied. More importantly, these novel MnO 2 /TiO 2 NTAs photoelectrodes proved to have excellent stability and reusability that would have great potentials for organic contaminants degradation in wastewater treatment.