Ying-Ying Shao,Wei-Dong Ye,Chun-Yan Sun,Chu-Lin Liu,Qi Wang
As typical persistent organic pollutants, polybrominated diphenyl ethers (PBDEs) have aroused high environmental concern because of their toxicity and recalcitrant degradation. Here we report the visible-light-induced degradation of PBDEs with AgI–TiO2 (>420 nm). A series of nano-structured AgI–TiO2 particles were synthesized by a deposition–precipitation method and characterized by SEM, TEM, XRD, XPS, BET and UV-Vis-DRS. The AgI–TiO2 hybrids showed high efficiency for degradation of PBDEs and excellent photostability in cyclic run experiments. The absorbance intensity and absorption ability of AgI–TiO2 hybrids and the properties of the solvents were found to greatly influence the efficiency of degradation of PBDEs. The 0.2-AgI–TiO2 (the mass ratio of Ag to P25 was about 20%) in CH3OH solution presented the highest reaction rate with 0.29 ± 0.02 h−1. Most interestingly, mechanistic pathways in the degradation of PBDEs were different under UV and visible light. Unlike the common single-electron transfer in the UV-TiO2 system, the debromination mechanism in the visible light/AgI–TiO2 system showed multi-electron transfer. The analysis of products showed that many different lower brominated congeners simultaneously appeared under visible light rather than being stepwise formed under UV. This implies that the special structure of AgI–TiO2 performs remarkably enhanced electron transfer, multi-electron transfer, and results in high photocatalytic activity. This research may provide a green and efficient method to remove halogenated pollutants by using visible light.
Wenbo Sun,Peiling Gao,Jiutao An,Jianan Li,Xinyong Li
Hydrogen sulfide (H 2 S), as both an endogenously gaseous signaling compound and an environmentally hazardous substance, has shown great relevance to human health and ecosystem safety. However, a reliable sensing platform for the facile detection of trace H 2 S is still a challenge to be addressed. Herein, a AgI-TiO 2 nanorods array electrode was fabricated through a hydrothermal method followed by ultrasonic impregnation treatment to construct an ultrasensitive photoelectrochemical H 2 S sensor. The decorated AgI could not only play a significant role in the enhancement of visible light absorbance as a narrow bandgap sensitizer but also contribute to the specific affinity towards sulfide as the recognition unit. In the presence of sulfide, multiple heterojunctions were established in situ due to I − -to-S 2− exchange at the AgI sites, proportionately increasing the photocurrent response of the functionalized PEC electrodes. The designed photoelectrochemical (PEC) sensing platform could achieve the quantitative determination of sulfide in a wide range of 1 ∼ 1000 nM with an effective detection limit of 1.25 nM. Additionally, the detection performances for practical H 2 S-containing waste gas and the biological environment were also evaluated. This work could broaden a new vision of the delicate design of interfaces for ultrasensitive environmental analysis.
Chloramphenicol (CAP) is an antibiotic used for a variety of infections, however, it is banned for use in food-producing animals due to its hazards to humans blood . Herein, the highly sensitive photoresponsive colorimetric immunoassay was exploited based on AgI/TiO 2 heterojunction nanomaterials . Firstly, chitosan modified AgI/TiO 2 photocatalyst (CS-AgI/TiO 2 ) was synthesized by deposition-precipitation method, which was characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR). Then, by utilizing CS-AgI/TiO 2 labeled CAP antibody as tags, a novel competitive-type immunoassay was constructed for detection of CAP on the surface of CAP-BSA modified magnetic bead. The color development of 3,3 ′ ,5,5 ′ -tetramethylbenzidine (TMB) was obtained under visible light irradiation (λ≥420 nm) and the assay was carried out in pH 3.0 ABS buffer solution by UV–Vis spectrophotometry . Under optimal conditions, the absorbance values decreased with the increasing of CAP levels in sample, which exhibited linear in the range of 0.03–12.53 nM with a detection limit of 0.03 nM. Meanwhile, the selectivity , repeatability, and stability were acceptable. Excitedly, no significant difference was observed for detection of the spiked CAP in the real food samples with the referenced values.
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