Engineering 0D/2D design of zinc sulfide quantum dots encapsulated with yttrium tungstate nanosheets for improving decomposition of organic dyes and doxycycline hydrochloride drug

Herein, it is demonstrated that 0D/2D design of zinc sulfide quantum dots encapsulated with yttrium tungstate nanosheets, which were subsequently used to increase the removal of brilliant blue (BB), methyl red (MR) dyes and doxycycline drug using UV-visible light. The produced ZnS-Y2WO6 nanohybrids exhibited excellent catalytic activity, reaching degradation efficiencies of around 89.92%, 80% and 85.51 % for BB, MR dyes and doxycycline drug, respectively, with a minimum irradiation duration of 120, 60 and 125 min. These nanohybrids outperformed Y2WO6 in terms of photocatalytic efficacy due to enhanced light absorption, efficient charge transfer, and decreased charge carrier recombination between ZnS and Y2WO6 nanoparticles. The synergistic combination of ZnS and Y2WO6 nanoparticles resulted in multiple active sites on the composite surface. Furthermore, the ZnS-Y2WO6 nanohybrids maintained excellent degradation efficiencies of 79.45% and 70.12% for BB and MR dyes, respectively, even after five consecutive cycles, with no significant loss of catalytic activity. The produced ZnS-Y2WO6 nanohybrids were thoroughly analyzed utilizing a variety of analytical methods. Furthermore, the degradation of organic dyes and doxycycline drug related possible mechanism were examined using experimental data, indicating the potential of ZnS-Y2WO6 nanohybrids as excellent photocatalytic materials for oxidizing organic dyes and drugs in aquatic conditions.

Recent advances in visible light-activated photocatalysts for degradation of dyes: A comprehensive review

The rapid development in industrialization and urbanization coupled with an ever-increasing world population has caused a tremendous increase in contamination of water resources globally. Synthetic dyes have emerged as a major contributor to environmental pollution due to their release in large quantities into the environment, especially owing to their high demand in textile, cosmetics, clothing, food, paper, rubber, printing, and plastic industries. Photocatalytic treatment technology has gained immense research attention for dye contaminated wastewater treatment due to its environment-friendliness, ability to completely degrade dye molecules using light irradiation, high efficiency, and no generation of secondary waste. Photocatalytic technology is evolving rapidly, and the foremost goal is to synthesize highly efficient photocatalysts with solar energy harvesting abilities. The current review provides a comprehensive overview of the most recent advances in highly efficient visible light-activated photocatalysts for dye degradation, including methods of synthesis, strategies for improving photocatalytic activity, regeneration and their performance in real industrial effluent. The influence of various operational parameters on photocatalytic activity are critically evaluated in this article. Finally, this review briefly discusses the current challenges and prospects of visible-light driven photocatalysts. This review serves as a convenient and comprehensive resource for comparing and studying the fundamentals and recent advancements in visible light photocatalysts and will facilitate further research in this direction.

Preparation and photocatalytic performance study of dual Z-scheme Bi2Zr2O7/g-C3N4/Ag3PO4 for removal of antibiotics by visible-light

At present, the high re-combination rate of photogenerated carriers and the low redox capability of the photocatalyst are two factors that severely limit the improvement of photocatalytic performance. Herein, a dual Z-scheme photocatalyst bismuthzirconate/graphitic carbon nitride/silver phosphate (Bi₂Zr₂O₇/g-C₃N₄/Ag₃PO₄ (BCA)) was synthesized using a co-precipitation method, and a dual Z-scheme heterojunction photocatalytic system was established to decrease the high re-combination rate of photogenerated carriers and consequently improve the photocatalytic performance. The re-combination of electron-hole pairs (e^- and h⁺) in the valence band (VB) of g-C₃N₄ increases the redox potential of e^- and h⁺, leading to significant improvements in the redox capability of the photocatalyst and the efficiency of e^--h⁺ separation. As a photosensitizer, Ag₃PO₄ can enhance the visible light absorption capacity of the photocatalyst. The prepared photocatalyst showed strong stability, which was attributed to the efficient suppression of photo-corrosion of Ag₃PO₄ by transferring the e^- to the VB of g-C₃N₄. Tetracycline was degraded efficiently by BCA-10% (the BCA with 10 wt.% of AgPO₄) under visible light, and the degradation efficiency was up to 86.2%. This study experimentally suggested that the BCA photocatalyst has broad application prospects in removing antibiotic pollution.

Properties, optimized morphologies, and advanced strategies for photocatalytic applications of WO3 based photocatalysts

The development of WO₃ based photocatalysts has gained considerable attention across the world, especially in the realm of environmental remediation and energy production. WO₃ has a band gap of 2.5- 2.7 eV that falls under the visible region and is thus a potential candidate to utilize in various photocatalytic processes. As an earth-abundant metal oxide, WO₃ discovered in 1976 displayed excellent electronic and morphological properties, good stability, and enhanced photoactivity with diverse crystal phases. Also, it unveils non-toxicity, high stability in drastic conditions, biocompatibility, low cost, excellent hole mobility (10 cm² V^-1s^-1), and tunable band gap. This review provides a comprehensive overview of the different properties of WO₃ inclusive of crystallographic, electrical, optical, thermoelectrical, and ferroelectric properties. The different morphologies of WO₃ based on dimensions were obtained by adopting different fabrication methods including inspecting their effects on the efficiency of WO₃. Numerous strategies to construct an ideal photocatalyst such as engineering crystal facets, surface defects, doping, heterojunction formation explaining specifically type-II, Z-scheme, and S-scheme mechanisms with addition to carbonaceous based WO₃ nanocomposites are summed up to explore the photocatalytic performance. The typical application of WO₃ is deliberated in detail involving the role and efficiency of WO₃ in pollutant degradation, CO₂ photoreduction, and water splitting. Besides, other applications of WO₃ as gas-sensor, bio-sensor, decomposition of VOCs, heavy metals ions adsorption, and antimicrobial property are also included. Moreover, the numerous aspects responsible for the high efficiency of WO₃-based nanocomposites with their challenges, opportunities, and future aspects are summarized. Hopefully, this review may inspire researchers to explore new ideas to boost the production of clean energy for the next generation.

In situ construction of a direct Z-scheme AgBr/α-Ag2WO4 heterojunction with promoted spatial charge migration and photocatalytic performance

A hierarchical AgBr/α-Ag₂WO₄ Z-scheme heterojunction was facially constructed for greatly improved photocatalytic activity towards pollutant elimination due to promoted spatial separation of carriers with high redox capacity.

A CeO2 Semiconductor as a Photocatalytic and Photoelectrocatalytic Material for the Remediation of Pollutants in Industrial Wastewater: A Review

The direct discharge of industrial wastewater into the environment results in serious contamination. Photocatalytic treatment with the application of sunlight and its enhancement by coupling with electrocatalytic degradation offers an inexpensive and green technology enabling the total removal of refractory pollutants such as surfactants, pharmaceuticals, pesticides, textile dyes, and heavy metals, from industrial wastewater. Among metal oxide—semiconductors, cerium dioxide (CeO2) is one of the photocatalysts most commonly applied in pollutant degradation. CeO2 exhibits promising photocatalytic activity. Nonetheless, the position of conduction bands (CB) and valence bands (VB) in CeO2 limits its application as an efficient photocatalyst utilizing solar energy. Its photocatalytic activity in wastewater treatment can be improved by various modification techniques, including changes in morphology, doping with metal cation dopants and non-metal dopants, coupling with other semiconductors, and combining it with carbon supporting materials. This paper presents a general overview of CeO2 application as a single or composite photocatalyst in the treatment of various pollutants. The photocatalytic characteristics of CeO2 and its composites are described. The main photocatalytic reactions with the participation of CeO2 under UV and VIS irradiation are presented. This review summarizes the existing knowledge, with a particular focus on the main experimental conditions employed in the photocatalytic and photoelectrocatalytic degradation of various pollutants with the application of CeO2 as a single and composite photocatalyst.

Fabrication of Ag2O/WO3 p-n heterojunction composite thin films by magnetron sputtering for visible light photocatalysis

Semiconductor-based nanostructures which are photo-catalytically active upon solar light irradiation were extensively used for environmental remediation due to the potential decomposition of various kinds of pollutants. In this work, we report the preparation of a sustainable thin film composite, i.e. Ag2O/WO3 p-n heterojunction, and investigation of its photocatalytic activity. To achieve the composite structure, WO3/Ag-WO3 layers were deposited over a quartz substrate by magnetron sputtering at room temperature and subsequently annealed at 823 to 923 K. The thin film structure, morphology, and chemical states were thoroughly characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron spectroscopy, and X-ray photoelectron spectroscopy. The obtained results revealed that the amorphous Ag-doped WO3 was crystallized into monoclinic WO3 and Ag2O, in which nanocrystalline Ag2O was diffused towards the surface of WO3. Optical transmittance spectra recorded by UV-vis-NIR spectroscopy revealed that the WO3/Ag-WO3 films became transparant in the visible region after annealing at high temperature (873 K and 923 K). The Ag2O/WO3 p-n heterojunction composite thin films showed high photocatalytic activity (0.915 × 10-3 min-1) under visible light irradiation, which is attributed to the efficiency of effective photogenerated charge-carrier formation and the reduced recombination rate of photogenerated electron-hole pairs. Unlike the powder-based photocatalysts, the reported thin film-based heterojunction photocatalyst could be very sustainable, and cost-effective.

Facile synthesis of new polyhedron-like WO3/butterfly-like Ag2MoO4 p–n junction photocatalysts with higher photocatalytic activity in UV/solar region light

A series of novel efficient polyhedron-like WO₃/butterfly-like Ag₂MoO₄ p–n junction photocatalysts (denoted as AMW-x) were designed and synthesized.

Tuning the electronic structure of Ag3PO4-based composites through a graphene oxide mediator for enhanced photocatalytic activity

A novel GO-supported APO/CFO composite was prepared, which exhibited excellent photocatalytic RhB degradation and HER performance under visible-light irradiation.

Efficient Z-scheme charge separation in WO3/PbWO4 for the removal of organic pollutants

The contact quality of a composite is an important factor for the transfer and separation of photogenerated carriers.