ABSTRACT
AgClxBr1-x composites with different halogen molar ratios (Cl/Br) were prepared by a facile ultrasound-assisted ion-exchange method. The formation of close contact between AgCl and AgBr facilitated the transportation of photoexcited charge carriers and contributed to the enhanced visible-light-driven photocatalytic degradation of different kinds of antibiotics. The AgClxBr1-x composites had a sphere-like morphology and tunable band gaps from 2.95 to 2.57 eV depending on Cl/Br mole ratios. Besides, the AgClxBr1-x composite was optimized by varying halogen mole ratios (Cl/Br) to achieve the highest photocatalytic activity. Results indicated that AgCl0.75Br0.25 showed the best photocatalytic degradation performance, which was about 2.36 and 2.78 times that of the single AgCl towards ciprofloxacin (CIP) and metronidazole (MNZ) degradation, respectively. Meanwhile, a possible photocatalytic degradation mechanism was discussed, and results indicated that the holes (h+) and â¢OH were the dominant active species in the AgCl0.75Br0.25 system.
Subject(s)
Light , Silver Compounds , Catalysis , Ciprofloxacin , Ion ExchangeABSTRACT
Semiconductor photocatalytic technology is a sustainable and less energy consuming one for nitrogen (N2) reduction to produce ammonia (NH3). In this study, flower-like hierarchical N doped MoS2 (N-MoS2) microsphere was synthesized as a photocatalyst by one-step solvothermal method, which was assembled by numerous interleaving nanosheets petals with thin thickness. Besides, Pt nanoparticles were loaded on the surface of N-MoS2 via photo-ultrasonic reduction method. The as-prepared Pt/N-MoS2 photocatalyst exhibited higher N2 fixation ability than that over pure MoS2 and N-MoS2, which can be attributed to that the N doping narrows the band gap, and the Schottky barrier due to the existence of Pt nanoparticles improves the charge transfer and carrier separation. The reduction of N2 with ultrasonic irradiation was also investigated under visible light irradiation to evaluate the sonophotocatalytic activity of the Pt/N-MoS2 microsphere. The results showed that the N2 reduction rate of sonophotocatalysis (133.8 µmol/g(cat)h) was higher than that of sonocatalysis and photocatalysis, which can be ascribed to the synergistic effect of ultrasound and visible light irradiation. The effects of catalyst dosage, ultrasonic power and ultrasonic pulse on the photocatalytic efficiency were also studied. Meanwhile, a possible mechanism for improved sonophotocatalytic performance was also proposed.
ABSTRACT
A highly uniform 3D flower-like hierarchical AgCl microsphere was prepared by sonochemical method with the existence of ß-dextrin. The 3D flower-like hierarchical structure can be ascribed to the existence of ß-dextrin, which provides nucleation sites for the growth of nanosheets because of the strong interaction between ß-dextrin and Ag+. The 3D flower-like hierarchical AgCl microspheres were assembled by numerous interleaving nanosheet petals with small thickness. Benefiting from the unique structural features, the as-prepared 3D flower-like hierarchical AgCl microsphere exhibited higher degradation efficiency with degrading 98.17% of methylene blue (MB) and 88.50% of tetracycline (TC) within 40 min, which were both remarkably higher than those of irregular AgCl under visible light irradiation. Besides, the photocatalytic degradation rate constant of 3D flower-like hierarchical AgCl microsphere (0.063 min-1) for MB was 3.94 times higher than that of irregular AgCl (0.016 min-1). Moreover, a possible mechanism for the formation and excellent photocatalytic performance of 3D flower-like hierarchical AgCl microsphere was also proposed.