Xiaofei Guo,Chuanxiang Qin,Mingyue Zhu,Jian-jun Wang,Jun Sun,Lixing Dai
A composite photocatalyst, with a BiOI/TiO2 heterojunction supported on carboxyl polystyrene spheres, was prepared using a two step hydrothermal reaction method. The products were characterized by X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results show that the polystyrene microspheres were covered with smaller-sized BiOI microspheres, while nano-sized TiO2 particles were deposited on the surface of the flower-like BiOI microspheres. As an internal electric field exists when BiOI is hybridized with TiO2, the photogenerated carriers could be separated effectively and the resulting composite photocatalyst PS/BiOI/TiO2 had better performance for degrading rhodamine B in aqueous solution under visible-light irradiation with a 40 W incandescent lamp than that of PS/BiOI. Meaningfully, the composite photocatalyst can be recycled easily by filtering.
Ruili Lyu,Yiting Lei,Chi Zhang,Gaiping Li,Runping Han,Lina Zou
Due to widespread application of chlorpyrifos for controlling pests in agriculture, the continuous accumulation of chlorpyrifos residue has caused serious environmental pollution .The detection of chlorpyrifos is of great significance for humans and environment because it can arise a series of diseases by inhibiting acetylcholinesterase (AChE) activity. Photoelectrochemical sensing, as an emerging sensing technology , has great potential in the detection of chlorpyrifos. It is urgent that find a suitable photoelectric sensing strategy to effectively monitor chlorpyrifos. Herein, an n-n heterojunction was constructed by uniformly immobilizing n-type 3DBiOI, which had loose porous structure composed of numerous small and thin nanosheets , on the surface of TiO 2 with anatase/rutile (AR-TiO 2 ) heterophase junction. Under light irradiation , the proposed BiOI/AR-TiO 2 n-n heterojunction exhibited excellent optical absorption characteristics and photoelectrochemical activity. Additionally, the photoelectrochemical sensing platform demonstrated excellent analytical performance in monitoring chlorpyrifos. Under optimized conditions, it showed a wide detection range of 1 pg mL −1 - 200 ng mL −1 and a detection limit (S/N = 3) as low as 0.24 pg mL −1 , with superior selectivity and stability. The ultra-sensitivity and great specificity for detection of chlorpyrifos can be ascribed to chelation between Bi (Ⅲ) and C=N and P=S bonds in chlorpyrifos, which had been confirmed in this work. Meanwhile, the PEC sensor also had potential application value for monitoring chlorpyrifos in water samples, lettuce and pitaya, which the recoveries of samples ranged from 96.9% to 104.7% with a relative standard deviation (RSD) of 1.11%–5.93%. This sensor provided a novel idea for constructing heterojunctions with high photoelectric conversion efficiency and had a high application prospect for the detection of chlorpyrifos and other structural analogues.
In this study, bismuth oxyiodide/titanium dioxide (BiOI/TiO 2 ) heterostructures with different molar ratios of Bi and Ti were synthesized by electrospinning and hydrothermal methods . The samples thus synthesized were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy . The results confirmed the presence of the BiOI/TiO 2 heterojunction with Bi/Ti molar ratios of 0.20–1 by electrospinning and hydrothermal methods . Photocatalytic activity was also evaluated by the degradation of methylene blue (MB) under visible-light irradiation. The 80% BiOI/TiO 2 heterostructure exhibited the best photocatalytic activity for the degradation of MB under visible-light irradiation.
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