Novel BaSnO₃/TiO₂@HNTs Heterojunction Composites with Highly Enhanced Photocatalytic Activity and Stability

Abstract

The novel BaSnO 3 /TiO 2 @HNTs photocatalysts were successfully synthesized by co-precipitation peroxide and sol-gel methods. Microstructures, morphologies, compositions, optical and electrochemical properties of the composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), Brunauer-Emmett-Teller (BET), electrochemical impedance spectroscopy (EIS) and ion chromatography (IC) methods. The effects of different mass ratios of BaSnO 3 and TiO 2 @HNTs, initial concentration and pH of methylene blue (MB) on the photocatalytic degradation performance of the composites were studied via photodegradation of MB under simulated sunlight irradiation. The characterization results showed that BaSnO 3 /TiO 2 heterojunction and halloysite nanotubes (HNTs) enhanced the electron-hole pairs separation. The BaSnO 3 /TiO 2 @HNTs (BTH-0.6) composites presented the highest specific surface area (67.957 m 2 /g), photocatalytic activity (92 %), and MB (C t = 40 mg/L, pH 7) degradation efficiency (2-4 times that of TiO 2 , BaSnO 3 and BaSnO 3 /TiO 2 ). Furthermore, the capture experiments verified that ⋅OH, h + and ⋅O 2 À were the main active substances during the photo-catalytic reaction, and a possible degradation mechanism was suggested for their photocatalytic degradation in the presence of BaSnO 3 /TiO 2 @HNTs.