Enhanced degradation of tetracycline under natural sunlight through the synergistic effect of Ag3PO4/MIL-101(Fe) photocatalysis and Fenton catalysis: Mechanism, pathway, and toxicity assessment

Here, we show that the adverse environmental and health effects of tetracycline (TC) can be efficiently reduced by encapsulating Ag₃PO₄ into MIL-101(Fe) to construct a Ag₃PO₄/MIL-101(Fe) heterojunction composite through advanced oxidation processes, such as Fenton catalysis, photocatalysis, and photo-Fenton catalysis. Notably, the reaction can be driven by natural sunlight and does not require any artificial energy source. Remarkably, the optimal degradation of TC can be achieved under different compositions of the composite system through photocatalysis and photo-Fenton catalysis. For photo-Fenton catalysis, the maximum degradation rate of TC (2.5730 min^-1) is achieved when the mass ratio of MIL-101(Fe) to Ag₃PO₄ in the composite is 5:1, which is 31.65- and 3.12-fold of that in the Ag₃PO₄ + PDS + Sunlight and MIL-101(Fe) + PDS+ Sunlight catalyst systems, respectively. Moreover, the internal conversion of matrix during photocatalysis and Fenton catalysis processes inhibits the photocorrosion of Ag₃PO₄ and improves the reusability of the composite. Furthermore, it is found that both radical and non-radical species participate in the TC degradation. Besides, the degradation products and catalytic mechanism of Ag₃PO₄ and Ag₃PO₄/MIL-101(Fe) systems are explored. The toxicity evaluation results suggest that the intermediates produced during Ag₃PO₄/MIL-101(Fe) catalysis have a lower biotoxicity than those produced during Ag₃PO₄ catalysis. Overall, this work provides an effective strategy to inhibit the inherent photocorrosion of Ag₃PO₄ and establishes an efficient catalytic system for the treatment of organic-contaminated wastewater under natural sunlight conditions.

Facile photo-ultrasonic assisted reduction for preparation of rGO/Ag2CO3 nanocomposites with enhanced photocatalytic oxidation activity for tetracycline

Various antibiotics in the aquatic systems have threat the aquatic ecosystem balance and the human health. In this study, a degradation treatment method for tetracycline (TC), one of the commonly used antibiotics, was explored by using novel photocatalysts of rGO/Ag₂CO₃ under simulated sunlight, because conventional treatment methods are not efficient on the removal of TC. rGO/Ag₂CO₃ nanocomposites were synthesized via a facile photo-ultrasonic assisted reduction method. More than 90% of TC was removed by 1% (weight_rGO/weight_composites) rGO/Ag₂CO₃ within 60 min at pH = 4, which was about 1.3 times higher than that of pure Ag₂CO₃. The cycling experiments indicated that 1% rGO/Ag₂CO₃ was highly stable and could be reused for at least 5 cycles without significant deactivation to its photocatalytic activity. In addition, the effects of pH, temperature, and dosage amount of 1% rGO/Ag₂CO₃ on photocatalytic degradation were investigated. Meanwhile, the effect of ultrasonic on the degradation of TC was also investigated. This study can provide a new method for the preparation of smaller nanosized materials and photocatalysts with high activity and stability for its environmental or other applications.

Facile One-Step Sonochemical Synthesis and Photocatalytic Properties of Graphene/Ag3PO4 Quantum Dots Composites

In this study, a novel graphene/Ag₃PO₄ quantum dot (rGO/Ag₃PO₄ QD) composite was successfully synthesized via a facile one-step photo-ultrasonic-assisted reduction method for the first time. The composites were analyzed by various techniques. According to the obtained results, Ag₃PO₄ QDs with a size of 1-4 nm were uniformly dispersed on rGO nanosheets to form rGO/Ag₃PO₄ QD composites. The photocatalytic activity of rGO/Ag₃PO₄ QD composites was evaluated by the decomposition of methylene blue (MB). Meanwhile, effects of the surfactant dosage and the amount of rGO on the photocatalytic activity were also investigated. It was found that rGO/Ag₃PO₄ QDs (W_rGO:W_composite = 2.3%) composite exhibited better photocatalytic activity and stability with degrading 97.5% of MB within 5 min. The improved photocatalytic activities and stabilities were majorly related to the synergistic effect between Ag₃PO₄ QDs and rGO with high specific surface area, which gave rise to efficient interfacial transfer of photogenerated electrons and holes on both materials. Moreover, possible formation and photocatalytic mechanisms of rGO/Ag₃PO₄ QDs were proposed. The obtained rGO/Ag₃PO₄ QDs photocatalysts would have great potentials in sewage treatment and water splitting.

Z-scheme Ag3PO4/POM/GO heterojunction with enhanced photocatalytic performance for degradation and water splitting

To develop solar light-driven photocatalysts with high activity and structural stability, Ag₃PO₄/POM/GO heterojunction has been successfully prepared by a facile method at room temperature.

Facile fabrication and enhanced visible-light photocatalytic activity of In2O3/Ag2CrO4 composites

The efficient charge transfer at the interfaces of In₂O₃/Ag₂CrO₄ composite due to the formation of Z-scheme system composed of In₂O₃, Ag and Ag₂CrO₄, which effectively improved the separation and transfer of photogenerated charge carriers.