To compare photodegradation processes in single- and binary-contaminant systems, a representative antibiotic (tetracycline) and insecticide (imidacloprid) were employed as two contaminants of emerging concern. Ag/AgBr modified BiOBr was synthesized hydrothermally in an ionic-liquid/water medium and characterized via various techniques to support mechanistic studies. As-prepared flower-shaped Ag/AgBr/BiOBr exhibits superior photocatalytic activity to Ag/AgBr and BiOBr. Parallel experiments were conducted in single-contaminant systems to optimize the solution chemistry for comparison studies; these suggested that the photodegradation rate (DR) is highest at 1.0 g L−1 at catalyst dosages ranging from 0.6 to 1.4 g L−1, while raising the initial concentration reduces the DR. Additionally, electrostatic interactions between the reactants and photocatalyst cause DR fluctuations at different pH values. In the mechanistic studies, the contributions of the dominant active species (˙O2− and h+) were analysed quantitatively through quenching tests with scavengers. Furthermore, electrostatic interactions between the reactants and the active species result in non-equilibrated contributions from ˙O2− and h+ in single-contaminant systems. Comparison studies distinctly demonstrated a synergistic effect in binary-contaminant systems, which is caused by the mutually complementary utilization of h+ and ˙O2− during the photodegradation of tetracycline and imidacloprid.
Zhu Wanrong,Song Jimei,Wang Xule,Lu Yun,Hu Gang,Yang Jie
A series of Ag/AgBr/BiOBr photocatalysts with different weight contents of Ag/AgBr were successfully constructed via a simple precipitation method in 80 °C water bath. Photocatalysts were characterized by XRD, XPS, SEM, TEM, N 2 Adsorption-Desorption (BET), and UV–Vis Diffuse Reflectance Spectroscopy (DRS). Compared with BiOBr and Ag/AgBr, all the composite photocatalysts show the prominent photocatalytic activity for the degradation of tetracycline (TC). Especially, 1:5Ag/AgBr/BiOBr (20%) has the highest reaction rate constant (kapp = 0.20 min −1 ). Moreover, according to the results of radical scavengers runs, ·OH and h + acted as the main reactive species in the degradation process. Based on above, a possible photocatalytic mechanism for organics degradation over Ag/AgBr/BiOBr was proposed. Interestingly, the redox cycle between O 2 /·O 2 − and Br − /Br 0 assisted with the surface plasmon resonance (SPR) effect of silver dramatically promotes the separation and transfer of electron–hole pairs, and improves the photocatalytic activity of the as-obtained composite samples.
Prostate cancer is one of the most common cancers in the world, and its early detection is vital to saving the lives of patients. In this research, a novel label-free photoelectrochemical immunosensor was designed for sensitive detection of prostate specific antigen (PSA). Ag 2 S sensitized on Ag/AgBr/BiOBr heterojunction could effectively inhibit photogenic holes recombination and improve photocurrent response and sensitivity. Ascorbic acid was an effective electron donor, which can effectively eliminate photo-generated holes. The photocurrent reduced linearly with the logarithm of PSA concentration ranged from 0.001 to 50 ng·mL −1 and the limit of detection was 0.25 pg·mL −1 . The designed sensor had the advantages of wide linear range, good stability, high reproducibility, and good selectivity. This study not only provided a method for efficient and sensitive detection of PSA, but also provided valuable reference ideas for the detection of other tumor markers.
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