Efficient visible-light-driven S-scheme AgVO3/Ag2S heterojunction photocatalyst for boosting degradation of organic pollutants

Construction of a novel S-scheme AgVO3/CaIn2S4 heterostructure for efficient photodegradation of tetracycline hydrochloride

Constructing an S-scheme system with highly active catalysts is a significant approach for improving the separation of photoinduced carriers to solve the related environmental aggravation. In this study, a well-designed S-scheme AgVO3/CaIn2S4 photocatalyst was synthesized for water purification by in situ growing CaIn2S4 nanocrystals on AgVO3 nanorod surfaces. The optimized AgVO3/CaIn2S4 heterostructure demonstrates an enhanced photocatalytic efficiency (94.1%) toward tetracycline hydrochloride (TCH) degradation compared with bare AgVO3 (42.6%) and CaIn2S4 (81.6%). The significant enhancement of photocatalytic activity is attributed to the S-scheme charge transfer mechanism in the AgVO3/CaIn2S4 heterostructure, which effectively directs photogenerated charge migration, boosts charge transfer, and preserves the high redox capacity of photoexcited electrons and holes on different active sites. This study is expected to offer insights into strategically designing and preparing S-scheme heterojunction photocatalysts to improve water purification.

Design of novel solar-light-induced KBi6O9I/Ag-AgVO3 nanophotocatalyst with Ag-bridged Z-scheme charge carriers separation and boosted photo-elimination of hospital effluents

In this research, a novel solar-light-induced KBi6O9I/Ag-AgVO3 nanophotocatalyst with an Ag-bridged Z-scheme structure has been designed and synthesized through a sonochemical method to photo-degrade antibiotic hospital contaminants under simulated solar-light irradiation. Synthesized nanophotocatalysts with varying KBi6O9I to Ag-AgVO3 weight ratios underwent N2 Adsorption-Desorption, XRD, TEM, UV-Vis DRS, FESEM and PL analyses. The Ag-bridged Z-scheme-structured KBi6O9I/Ag-AgVO3 (1:1) nanophotocatalyst, demonstrated broad light absorption within the solar-light spectrum and showcased effective photocatalytic efficacy in degrading tetracycline antibiotic (88.3% and 83.5% removal for 25 and 50 mg/L, respectively, after 120 min). This performance outperformed other composited photocatalysts, as well as pure Ag-AgVO3 and KBi6O9I photocatalysts. The enhanced degradation efficiency of the KBi6O9I/Ag-AgVO3 (1:1) composite can be ascribed to the synergistic interaction of various elements. These include the surface plasmon resonance impact of silver nanoparticles, their pronounced sensitivity to solar irradiation, and the Z-scheme heterojunction configuration. Collectively, these factors work together to minimize the recombination rate of photoinduced electron-hole pairs, thereby amplifying the efficacy of photodegradation. Furthermore, the KBi6O9I/Ag-AgVO3 (1:1) composite photocatalyst displayed sustained pollutants elimination performance even after undergoing four consecutive cycles.

Enhanced dye removal using montmorillonite modified with graphene quantum dots in sustainable salep nanocomposite hydrogel

This research investigated the utilization of graphene quantum dot/montmorillonite (GQD/MMT) as an effective nanofiller in a hydrogel composed of salep biopolymer. The semi-IPN hydrogel was synthesized using salep as the substrate, acrylamide (AAm) as the monomer, ammonium persulfate (APS) as an initiator in free radical polymerization, and N,N'-methylenebisacrylamide (MBA) as a cross-linking agent. The hydrogels were applied to remove safranin (SA), methylene blue (MB), crystal violet (CV), methyl green (MG), congo red (CR), and malachite green (MG) dyes from the water. The diverse properties were analyzed using a scanning electron microscope, fourier infrared spectroscopy, mapping, energy dispersive spectroscopy, weighing analysis, X-ray diffraction, and thermal stability analyses. The optimism of the prepared adsorbent in dye absorption was evaluated by measuring the swelling amount, pH impact, adsorbent dosage, and contact time. The adsorption calculations were described using kinetics and isotherm models. The results indicated that the Langmuir isotherm model (R2 = 99.6) and the pseudo-second-order kinetic model (R2 = 99.9) provided the best fit for the absorption process of MB. The presence of additional amounts of GQD/MMT had a reciprocal effect on the adsorption efficiency due to the accumulation of GQD/MMT in the semi-interpenetrating polymer network (semi-IPN (structure. The findings revealed that the samples exhibited high thermal stability, and the absorption process was primarily chemical. Furthermore, the nanocomposite hydrogels demonstrated distinct mechanisms for absorbing anionic dye (CR) and cationic dye (MB). Under optimal conditions, using 7 wt% GQD/MMT at a concentration of 5 ppm, pH = 7, an adsorbent dosage of 50 mg, at room temperature, and a contact time of 90 min, the maximum removal efficiencies were achieved: MB (96.2%), SA (98.2%), MG (86%), CV (99.8%), MG (95.8%), and CR (63.4%). These results highlight the adsorbent's high absorption capacity, rapid removal rate, and reusability, demonstrating its potential as an eco-friendly and cost-effective solution for removing dyes from water.

Photocatalytic Enhancement Strategy with the Introduction of Metallic Bi: A Review on Bi/Semiconductor Photocatalysts

Semiconductor photocatalysis has great potential in the fields of solar fuel production and environmental remediation. Nevertheless, the photocatalytic efficiency still constrains its practical production applications. The development of new semiconductor materials is essential to enhance the solar energy conversion efficiency of photocatalytic systems. Recently, the research on enhancing the photocatalytic performance of semiconductors by introducing bismuth (Bi) has attracted widespread attention. In this review, we briefly overview the main synthesis methods of Bi/semiconductor photocatalysts and summarize the control of the micromorphology of Bi in Bi/semiconductors and the key role of Bi in the catalytic system. In addition, the promising applications of Bi/semiconductors in photocatalysis, such as pollutant degradation, sterilization, water separation, CO2 reduction, and N2 fixation, are outlined. Finally, an outlook on the challenges and future research directions of Bi/semiconductor photocatalysts is given. We aim to offer guidance for the rational design and synthesis of high-efficiency Bi/semiconductor photocatalysts for energy and environmental applications.

Construction of Bi/BiOI/BiOCl Z-scheme photocatalyst with enhanced tetracycline removal under visible light

Bi/BiOI/BiOCl composite photocatalyst was constructed by one-step stirring approach at ambient environment to remove of tetracycline (TC) antibiotics via photodegradation in aqueous medium. A systematic discussion of the architecture, composition, formation, photochemical performance and photocatalytic activity of Bi/BiOI/BiOCl was carried out. By adjusting the experimental conditions, it was found that the Bi/BiOI/BiOCl photocatalyst obtained by using 0.7 mmol NaBH4, I/Cl = 5% and reacting for 6 h had the greatest removal performance. Under visible light irradiation, the photocatalytic degradation efficiency of TC reached 90.3% within 60 min, surpassing that of single BiOCl and BiOI. Through the active species removal experiment, it was determined that •O2- made a primary contribution to the photocatalytic degradation process. Moreover, the formation of Z-scheme heterojunction in Bi/BiOI/BiOCl was discussed, analyzing the photocatalytic mechanism and TC degradation pathway. The ecological toxicity of TC solution before and after degradation to rice seedlings was preliminarily tested. This study provides an idea for one-step synthesis of bismuth-based composite photocatalysts, with potential applications in the photocatalytic degradation of antibiotics.

A novel magnetic AgVO3/rGO/CuFe2O4 hybrid catalyst for efficient hydrogen evolution and photocatalytic degradation

A superior semiconductor material with efficient charge separation and easy reuse could be a promising route for efficient photocatalytic hydrogen evolution and pollutant degradation. AgVO₃ is one of the best visible light active materials which has attracted much attention for several biological and environmental applications. In the aim of enhancing its stability and recyclability a novel AgVO₃/rGO/CuFe₂O₄ heterojunction was prepared by hydrothermal method for hydrogen generation (H₂) and 4-nitrophenol (4-NP) degradation as well. The composite was well characterized by XRD, SEM, HR-TEM, XPS and VSM. The morphological images suggested the rod shaped AgVO₃ and irregular shaped CuFe₂O₄ are unevenly distributed on reduced graphene oxide (rGO) layers. The hydrogen evolution results indicated that the composite showed around 8.937 mmol g^-1h^-1 of H₂ generation which was ∼2.3 times and ∼9.2 times higher than pure AgVO₃ (3.895 mmol g^-1h^-1) and CuFe₂O₄ (0.96 mmol g^-1h^-1) respectively. The 4-NP degradation efficiency of the prepared composite was observed as 94.7% (k = 0.01841 min^-1) which is much higher than the AgVO₃ (66.3%) and CuFe₂O₄ (38.2%) after 4 h of irradiation. The higher efficiency could be attributed to the heterojunction formation and faster charge separation. The radical trapping results indicated that the •OH, O₂•- and photogenerated h⁺ are the main species responsible for efficient activity. The AgVO₃/rGO/CuFe₂O₄ heterojunction showed 49.6 emu/g of saturation magnetization and confirms that it could be easily separated with an external magnet, and showed 85.3% of degradation efficiency even after 6 recycles which indicated its higher stability and recyclability. Thus, our study provides new insight into hydrogen generation and phenol degradation using AgVO₃ based recyclable composites.