Controllable one-pot synthesis of a nest-like Bi2WO6/BiVO4 composite with enhanced photocatalytic antifouling performance under visible light irradiation

Pseudomonas aeruginosa and related antibiotic resistance genes as indicators for wastewater treatment

This review aims to examine the existence of Pseudomonas aeruginosa (P. aeruginosa) and their antibiotic resistance genes (ARGs) in aquatic settings and the alternative treatment ways. P. aeruginosa in a various aquatic environment have been identified as contaminants with impacts on human health and the environment. P. aeruginosa resistance to multiple antibiotics, such as sulfamethoxazole, ciprofloxacin, quinolone, trimethoprim, tetracycline, vancomycin, as well as specific antibiotic resistance genes including sul1, qnrs, blaVIM, blaTEM, blaCTX, blaAIM-1, tetA, ampC, blaVIM. The development of resistance can occur naturally, through mutations, or via horizontal gene transfer facilitated by sterilizing agents. In addition, an overview of the current knowledge on inactivation of Pseudomonas aeruginosa and ARG and the mechanisms of action of various disinfection processes in water and wastewater (UV chlorine processes, catalytic oxidation, Fenton reaction, and ozonation) is given. An overview of the effects of nanotechnology and the resulting wetlands is also given.

Recent developments, advances and strategies in heterogeneous photocatalysts for water splitting

Photocatalytic water splitting (PWS) is an up-and-coming technology for generating sustainable fuel using light energy. Significant progress has been made in the developing of PWS innovations over recent years. In addition to various water-splitting (WS) systems, the focus has primarily been on one- and two-steps-excitation WS systems. These systems utilize singular or composite photocatalysts for WS, which is a simple, feasible, and cost-effective method for efficiently converting prevalent green energy into sustainable H2 energy on a large commercial scale. The proposed principle of charge confinement and transformation should be implemented dynamically by conjugating and stimulating the photocatalytic process while ensuring no unintentional connection at the interface. This study focuses on overall water splitting (OWS) using one/two-steps excitation and various techniques. It also discusses the current advancements in the development of new light-absorbing materials and provides perspectives and approaches for isolating photoinduced charges. This article explores multiple aspects of advancement, encompassing both chemical and physical changes, environmental factors, different photocatalyst types, and distinct parameters affecting PWS. Significant factors for achieving an efficient photocatalytic process under detrimental conditions, (e.g., strong light absorption, and synthesis of structures with a nanometer scale. Future research will focus on developing novel materials, investigating potential synthesis techniques, and improving existing high-energy raw materials. The endeavors aim is to enhance the efficiency of energy conversion, the absorption of radiation, and the coherence of physiochemical processes.

Hydrothermal synthesis of spindle structure copper ferrite-graphene oxide nanocomposites for enhanced photocatalytic dye degradation and in-vitro antibacterial activity

In this study, a one-step hydrothermal approach was used to make pure magnetic copper ferrite (CuFe2O4) and copper ferrite-graphene oxide (CuFe2O4-rGO) nanocomposites (NCs) and spinel structure CuFe2O4 with a single phase of tetragonal CuFe2O4-rGO-NCs was confirmed by the XRD. Then, characterization of CuFe2O4-rGO-NCs was done using ng Raman spectroscopy, FT-IR, TGA-DTA, EDS, SEM, and TEM. The synthesized NCs was exposed to UV light to evaluate its photocatalytic activity for the degradation of methylene blue (MB) and rhodamine B (RhB) with CuFe2O4 and CuFe2O4-rGO-NCs, respectively. The catalyst CuFe2O4-rGO-NCs provided higher degradation of MB (94%) than for RhB (86%) under UV light irradiation compared to CuFe2O4. Further, the antibacterial activities of CuFe2O4-NPs and CuFe2O4-rGO-NCs were tested against Gram-negative and -positive bacterial pathogens such as Vibrio cholera (V. cholera); Escherichia coli (E. coli); Pseudomonas aeruginosa (P. aeruginosa); Bacillus subtilis (B. subtilis); Staphylococcus aureus (S. aureus); and Staphylococcus epidermidis (S. epidermidis) by well diffusion method. At 100 μg/mL concentrations of CuFe2O4-rGO-NCs, maximal growth inhibition was shown against E. coli (18 mm) and minimum growth inhibition against S. epidermidis (12 mm). This study suggests that CuFe2O4-rGO-NCs as a high-efficacy antibacterial material and plays an important role in exhibiting higher sensitivity depending on concentrations. The results encourage that the synthesized CuFe2O4-rGO-NCs can be used as a promising material for the antibacterial activity and also for dye degradation in the water/wastewater treatment plants.

Facile fabrication of AgVO3/rGO/BiVO4 hetero junction for efficient degradation and detoxification of norfloxacin

In the recent past, the development of efficient materials for degradation and detoxification of antibiotics has gained more attention in wastewater treatment process. As a visible light active material AgVO₃ has attracted much concern in environmental remediation. To improve its efficiency and stability, a novel heterojunction was prepared by combining AgVO₃ with rGO and BiVO₄ through a hydrothermal method. The prepared AgVO₃/rGO/BiVO₄ composite was further utilized for effective detoxification of Norfloxacin (NFC) antibiotic. The morphological analysis revealed the clear rod shaped AgVO₃ and leaf like BiVO₄ that are evenly distributed on reduced graphene oxide (rGO) layers. The visible light absorbance and the catalytic activity of AgVO₃/rGO/BiVO₄ was dramatically improved compared to pure AgVO₃ and BiVO₄. From the results it showed that the degradation efficiency of AgVO₃/rGO/BiVO₄ (∼96.1%, k = 0.01782 min^-1) was 2.5 times higher than pure AgVO₃ and 3.4 times higher than the pure BiVO₄ respectively towards NFC after 90 min. The higher efficiency could be attributed to the heterojunction formation and faster charge separation. The radical trapping experiments results indicated that the •OH, and O₂•- are the main species responsible for degradation. The degradation products of NFC were analysed through ESI-LC/MS and pathway was proposed. Furthermore, the toxicity assessment of pure NFC and its degradation products was studied using E. coli as the model bacteria through colony forming unit assay and the results indicated the efficient detoxification was attained during the degradation process. Thus, our study provides new insight into detoxification of antibiotics using AgVO₃ based composites.

Photo-electrocatalytic based removal of acetaminophen: Application of visible light driven heterojunction based BiVO4/BiOI photoanode

The presence of organic micro-pollutants (OMPs) in wastewater treatment effluents is becoming a major threat to the water safety for aquatic and human health. Photo-electrocatalytic based advanced oxidation process (AOP) is one of the emerging and effective techniques to degrade OMPs through oxidative mechanism. This study investigated the application of heterojunction based BiVO₄/BiOI photoanode for acetaminophen (40 μg L^-1) removal in demineralized water. Photoanodes were fabricated by electrodeposition of BiVO₄ and BiOI photocatalytic layers. Optical (UV-vis diffusive reflectance spectroscopy), structural (XRD, SEM, EDX) and opto-electronic (IPCE) characterization confirmed the successful formation of heterojunction for enhanced charge separation efficiency. The heterojunction photoanode showed incident photon to current conversion efficiency of 16% (λ_max = 390 nm) at an external voltage of 1 V under AM 1.5 standard illumination. The application of the BiVO₄/BiOI photoanode in the removal of acetaminophen at 1 V (external bias) vs Ag/AgCl under simulated sunlight showed 87% removal efficiency within the first 120 min compared to 66% removal efficiency of the BiVO₄ photoanode. Similarly, combining BiVO₄ and BiOI exhibited 57% increase in first order removal rate coefficient compared to BiVO₄. The photoanodes also showed moderate stability and reusability by showing 26% decrease in overall degradation efficiency after three cycles of each 5 h experiment. The results obtained in this study can be considered as a stepping stone towards the effective removal of acetaminophen as an OMP present in wastewater.

Construction of a Bi2WO6/BiVO4 photocatalytic system for efficient visible light degradation of tetracycline drugs

A Bi₂WO₆/BiVO₄ composite photocatalytic material was synthesized by the hydrothermal method, and achieved the effective degradation of oxytetracycline (OTC) and tetracycline (TC) under visible light. The compositions, structures, chemical states and optoelectronic properties of Bi₂WO₆, BiVO₄ and Bi₂WO₆/BiVO₄ composites were characterized by systematic characterization. The results show that the existence of the heterojunction interface facilitates the separation of photogenerated carriers. Compared with the pure catalyst of Bi₂WO₆ and BiVO₄, the Bi₂WO₆/BiVO₄ composite material significantly improves the degradation efficiency of OTC and TC. The degradation rate is 6.22 and 3.02 times higher than that of Bi₂WO₆ and BiVO₄, respectively. Through the free radical quenching experiments, it is known that photogenerated holes (h⁺) and superoxide anion free radicals (·O₂ ^-) are the main active substances in the degradation of OTC. By analyzing the process of photocatalytic degradation of OTC, there are mainly six intermediates during the process. Their possible degradation pathways are also inferred in this paper.

Synthesis of Bimetallic BiPO4/ZnO Nanocomposite: Enhanced Photocatalytic Dye Degradation and Antibacterial Applications

Multidrug-resistant strains (MDRs) are becoming a major concern in a variety of settings, including water treatment and the medical industry. Well-dispersed catalysts such as BiPO₄, ZnO nanoparticles (NPs), and different ratios of BiPO₄/ZnO nanocomposites (NCs) were synthesized through hydrothermal treatments. The morphological behavior of the prepared catalysts was characterized using XRD, Raman spectra, PL, UV-Vis diffuse reflectance spectroscopy (UV-DRS), SEM, EDX, and Fe-SEM. MDRs were isolated and identified by the 16s rDNA technique as belonging to B. flexus, B. filamentosus, P. stutzeri, and A. baumannii. The antibacterial activity against MDRs and the photocatalytic methylene blue (MB) dye degradation activity of the synthesized NPs and NCs were studied. The results demonstrate that the prepared BiPO₄/ZnO-NCs (B1Z4-75:300; NCs-4) caused a maximum growth inhibition of 20 mm against A. baumannii and a minimum growth inhibition of 12 mm against B. filamentosus at 80 μg mL^-1 concentrations of the NPs and NCs. Thus, NCs-4 might be a suitable alternative to further explore and develop as an antibacterial agent. The obtained results statistically justified the data (p ≤ 0.05) via one-way analysis of variance (ANOVA). According to the results of the antibacterial and photocatalytic study, we selected the best bimetallic NCs-4 for the photoexcited antibacterial effect of MDRs, including Gram ve⁺ and Gram ve^- strains, via UV light irradiation. The flower-like NCs-4 composites showed more effectiveness than those of BiPO₄, ZnO, and other ratios of NCs. The results encourage the development of flower-like NCs-4 to enhance the photocatalytic antibacterial technique for water purification.

Bi-based photocatalysts for bacterial inactivation in water: Inactivation mechanisms, challenges, and strategies to improve the photocatalytic activity

Bi-based photocatalysts have been considered suitable materials for water disinfection under natural solar light due to their outstanding optical and electronic properties. However, until now, there are not extensive reviews about the development of Bi-based materials and their application in bacterial inactivation in aqueous solutions. For this reason, this work has focused on summarizing the state of the art related to the inactivation of Gram- and Gram + pathogenic bacteria under visible light irradiation using different Bi-based micro and nano structures. In this sense, the photocatalytic bacterial inactivation mechanisms are analyzed, considering several modifications. The factors that can affect the photocatalytic performance of these materials in real conditions and at a large scale (e.g., water characteristics, pH, light intensity, photocatalyst dosage, and bacteria level) have been studied. Furthermore, current alternatives for improving the photocatalytic antibacterial activity and reuse of Bi-based materials (e.g., surface engineering, crystal facet engineering, doping, noble metal coupling, heterojunctions, Z-scheme junctions, coupling with graphene derivatives, magnetic composites, immobilization) have been explored. According to several reports, inactivation rate values higher than 90% can be achieved by using the modified Bi-based micro/nano structures, which become them excellent candidates for photocatalytic water disinfection. However, these innovative photocatalytic materials bring a variety of future difficulties and opportunities in water disinfection.

One-Step Hydrothermal Synthesis of Nanostructured MgBi2O6/TiO2 Composites for Enhanced Hydrogen Production

A highly efficient MgBi2O₆ (MBO)/TiO₂ heterostructured photocatalyst for the evolution of H₂ was successfully prepared using a one-step hydrothermal method. The phase structure, microstructure and optical properties of the MBO/TiO₂ composites were investigated by various experimental techniques. A series of H₂ production experiments were performed under visible light. The measured results indicated that the nanostructured MBO/TiO₂ composite, with a stoichiometric molar ratio of MBO:TiO₂ = 0.2%, displayed the best H₂ production rate of 3413 μmol h⁻¹ g⁻¹. The excellent photocatalytic performance of the obtained composite material was due to the heterojunction formed between MBO and TiO₂, which reduced the charge transfer resistance and accelerated the separation efficiency of the photogenerated electron–hole pairs. The reaction mechanism was also discussed in detail.

Photocatalytic dye degradation and photoexcited anti-microbial activities of green zinc oxide nanoparticles synthesized via Sargassum muticum extracts

Drug-resistant superbugs (DRS) were isolated from hospital sewage waste and confirmed by a 16S rDNA molecular technique as B. filamentosus, B. flexus, P. stutzeri, and A. baumannii.

An effective CuO/Bi2WO6 heterostructured photocatalyst: Analyzing a charge-transfer mechanism for the enhanced visible-light-driven photocatalytic degradation of tetracycline and organic pollutants

Over the past few years, industrial pollution has had a negative impact on aquatic life by releasing significant amounts of hazardous chemicals into the ecosystem. Therefore, it is imperative to develop photocatalytic materials with good photocatalytic activity and easy separation. Photocatalytic degradation has been employed for the removal of such contaminants using binary hybrid nanocomposites as photocatalysts. In the present study, binary CuO/Bi₂WO₆ (CuBW) nanocomposites with different loadings of Bi₂WO₆ (~5, 10, and 15 mg) were successfully constructed using a simple hydrothermal method and used as a potential photocatalyst for the degradation of tetracycline (TC) and methylene blue (MB) under visible-light irradiation. The structure, surface morphology, and optical properties were studied to investigate the formation of the heterostructure. Among the prepared samples, the CuBW nanocomposite containing the optimum content of Bi₂WO₆ (~10 mg) exhibited superior activity toward the photocatalytic degradation of TC (97.72%) in 75 min and MB (99.43%) in 45 min under visible-light illumination. Radical trapping experiments suggested that holes and •OH radicals were the dominant reactive species during the photocatalytic process. The photoelectrochemical results also confirmed the improved separation and transfer of electron-hole pairs at the interface of Bi₂WO₆ and CuO. Our results demonstrate that the binary CuO/Bi₂WO₆ nanocomposite has significant potential applications in the field of photocatalysis due to its enhanced separation of the photoexcited charge carriers and strong synergistic interactions.

Carbon quantum dots sensitized 2D/2D carbon nitride nanosheets/bismuth tungstate for visible light photocatalytic degradation norfloxacin

A novel carbon quantum dots (CQDs) sensitized 2D/2D carbon nitride nanosheets and bismuth tungstate composite (CQD-CNs/BWO) was successfully prepared via the facile hydrothermal method and used for the photocatalytic degradation of norfloxacin (NOR). During 120 min irradiation test, CQD-CNs/BWO exhibited 9 and 1.76 times higher photocatalytic activity than CNs and BWO, respectively. CQDs and constructed 2D/2D structure could not only improve the light harvesting but also promote the generation and separation of electron-holes. The existing inorganic ions in solution (e.g. bicarbonate ions, chlorine ions, and sulfate ions) could inhibit NOR degradation. Based on the electron spin resonance and free radicals inhibition tests, the holes and superoxide radicals rather than hydroxyl radicals were the main reactive species. The intermediates and possible pathways were proposed, and the antibacterial activity of the treated solution after the reaction was evaluated via bacteriostatic tests. The prepared composite material with high photocatalytic activity and stability is potentially effective for the degradation of antibiotics in wastewater.

Progress on photocatalytic semiconductor hybrids for bacterial inactivation

Due to its use of green and renewable energy and negligible bacterial resistance, photocatalytic bacterial inactivation is to be considered a promising sterilization process. Herein, we explore the relevant mechanisms of the photoinduced process on the active sites of semiconductors with an emphasis on the active sites of semiconductors, the photoexcited electron transfer, ROS-induced toxicity and interactions between semiconductors and bacteria. Pristine semiconductors such as metal oxides (TiO₂ and ZnO) have been widely reported; however, they suffer some drawbacks such as narrow optical response and high photogenerated carrier recombination. Herein, some typical modification strategies will be discussed including noble metal doping, ion doping, hybrid heterojunctions and dye sensitization. Besides, the biosafety and biocompatibility issues of semiconductor materials are also considered for the evaluation of their potential for further biomedical applications. Furthermore, 2D materials have become promising candidates in recent years due to their wide optical response to NIR light, superior antibacterial activity and favorable biocompatibility. Besides, the current research limitations and challenges are illustrated to introduce the appealing directions and design considerations for the future development of photocatalytic semiconductors for antibacterial applications.

Multifunctional graphene-based nanocomposites for simultaneous enhanced photocatalytic degradation and photothermal antibacterial activity by visible light

A new strategy for the wastewater treatment was proposed by combining polyvinylpyrrolidone-functionalized silver nanoparticles with reduced graphene oxide (AgNPs-PVP@rGO) as a visible light-triggered photoactive nanocomposite. The nanocomposite with enhanced photocatalytic degradation and photothermal antibacterial activity can simultaneously decrease the content of organic pollutants and bacteria in the wastewater under visible light irradiation. The efficiency of photocatalytic degradation can be significantly improved by the conjugation of AgNPs onto the rGO surface. The water solubility and dispersion of nanocomposite can be increased via PVP functionalization, without stirring during the photocatalytic process. Under the optimal synthesis condition, AgNPs-PVP@rGO has a photocatalytic degradation efficiency of 90.1% for rhodamine B, which is 6.9 and 1.8 times higher than that of polyvinylpyrrolidone-functionalized silver nanoparticles and rGO alone, respectively. More importantly, the degradation efficiency of optimal AgNPs-PVP@rGO sol on rhodamine B is significantly higher than that of its block suspension in the same amount, indicating that the sol with more specific surface area is conducive to the photocatalytic reaction. Meanwhile, the AgNPs-PVP@rGO with excellent photothermal activity can effectively inhibit the bacterial growth. This functional modification of graphene provides a new strategy for simultaneous treatment of multiple pollutants in wastewater. The AgNPs-PVP@rGO nanocomposites for simultaneous enhanced photocatalytic degradation and photothermal antibacterial activity by visible light.

Enhanced solar-light-driven photocatalytic and photoelectrochemical properties of zinc tungsten oxide nanorods anchored on bismuth tungsten oxide nanoflakes

At present, sustainable water supply and energy generation are the most important challenges faced by humankind globally. Thus, it is crucial to progress ecological techniques for sustainable removal of organic pollutants from wastewater and generation of hydrogen as an alternative to fossil fuels. In this study, zinc tungsten oxide (ZnWO₄) nanorods, bismuth tungsten oxide (Bi₂WO₆) nanoflakes, and Bi₂WO₆/ZnWO₄ (BO-ZO) nanocomposites were prepared via a simple hydrothermal approach. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, diffuse reflectance spectroscopy, and electrochemical analyses were conducted to confirm the formation of the BO-ZO heterostructure. The structural and morphological analyses revealed that the ZnWO₄ nanorods were moderately dispersed on the Bi₂WO₆ nanoflakes. The bandgap tuning of BO-ZO nanocomposite confirmed the establishment of the heterostructure with band bending properties. The BO-ZO nanocomposite could degrade 99.52% of methylene blue (MB) within 60 min upon solar-light illumination. The photoelectrochemical (PEC) measurement results showed that the BO-ZO nanocomposite showed low charge-transfer resistance and high photocurrent response with good stability. The BO-ZO photoanode showed a low charge-transfer resistance of 35.33 Ω and high photocurrent density of 0.1779 mA/cm² in comparison with Ag/AgCl in a 0.1 M Na₂SO₃ electrolyte under solar-light illumination. The MB photocatalytic degradation and PEC water oxidation mechanisms of the nanocomposite were investigated.

Photocatalytic antifouling coating based on carbon nitride with dynamic acrylate boron fluorinated polymers

Study on the preparation and properties of an environmentally friendly photocatalytic antifouling coating.

Hydrothermal synthesis of cotton-based BiVO4/Ag composite for photocatalytic degradation of C.I. Reactive Black 5

Photocatalytic materials with high efficiency and convenient recyclability have attracted great interest for the treatment of printing and dyeing wastewater. In this paper, a narrow band gap BiVO₄ photocatalyst was loaded onto Ag modified cotton fabric by a hydrothermal method. The prepared composite materials were characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and ultraviolet visible light absorption spectroscopy (UV-vis). The composite materials as prepared show superb photocatalytic activity and reusable performance for the degradation of C.I. Reactive Black 5 (RB5). The degradation rate can reach 99% within 90 min under 1 kW xenon lamp irradiation, and over 90% of the photocatalytic performance is preserved even after five recycles. Furthermore, the photocatalytic mechanism was proposed by spectral analysis and free radical trapping experiments.

Visible-light-driven photocatalytic degradation of rhodamine B using Bi2WO6/GO deposited on polyethylene terephthalate fabric

Abstract

The environmental repercussions of wastewater from the dye process mean that it is very important to obtain an eco-friendly photocatalyst that would degrade wastewater. Herein, bismuth tungstate/graphene oxide (Bi2WO6/GO) composites are fabricated through in-situ hydrothermal reaction and then the Bi2WO6/GO photocatalysts are deposited onto polyethylene terephthalate (PET) fabric. The obtained Bi2WO6/GO deposited PET fabrics are then characterized through XPS, Raman, SEM, TEM, XRD, UV-vis, BET method and photoluminescence spectroscopy (PL) to investigate their chemical and crystal structures, morphology, optical property, surface area and photochemical properties. Photocatalytic performance is studied through examining the rate of degrading rhodamine B (RhB) under visible light. Surface of PET fibers is densely covered with Bi2WO6/GO. Bi2WO6/GO deposited PET fabrics show a broad absorption band in the visible spectra. Removal rate of RhB on the Bi2WO6/GO deposited PET fabric is the highest with the GO content of 2 g/L (labeled as Bi2WO6/2 g/LGO). The result of active species experiment shows that superoxide radicals (·O2−) plays a major role in the degradation of RhB. Moreover, Bi2WO6/2 g/LGO deposited PET fabric shows excellent cycle stability of photocatalytic degradation for RhB. The findings in this work can be extended to preparation other types of composite on the textile for photocatalysis, which can be applied to remove dyes in the wastewater produced by the textile or leather industry.

Graphical abstract

Photocatalytic Degradation and Antibacterial Properties of Fe3+-Doped Alkalized Carbon Nitride

Discovering novel materials and improving the properties of existing materials are the main goals in the field of photocatalysis to increase the potential application of the materials. In this paper, a modified graphitic carbon nitride (g-C₃N₄) photocatalyst named Fe³⁺-doped alkalized carbon nitride, which couples the photocatalytic reaction with the Fenton reaction, is introduced to demonstrate its Rhodamine B (RhB) degradation and antibacterial properties. Under visible-light irradiation, the degradation rate of RhB was 99.9% after 200 min, while the antibacterial rates of Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) after 300 min were 99.9986%, 99.9974%, and 99.9876%, respectively. Moreover, the repetitive experiments of RhB degradation demonstrate that the proposed photocatalysts have excellent stability and reusability. The active free radical trapping experiments reveal that the superoxide radical (·O2−) is the dominant reactive oxygen species. In addition, the Fenton reaction is introduced into the photocatalytic system due to the doping of Fe³⁺, and the hydroxyl radical (·OH) produced from the Fenton reaction further enhances the photocatalytic performance. The remarkable improvement in photocatalytic performance of the proposed photocatalyst can be attributed to its broader UV–visible absorption characteristic and the occurrence of the Fenton reaction.

Towards visible light driven photoelectrocatalysis for water treatment: Application of a FTO/BiVO4/Ag2S heterojunction anode for the removal of emerging pharmaceutical pollutants

Pharmaceuticals have been classified as emerging water pollutants which are recalcitrant in nature. In the quest to find a suitable technique in removing them from contaminated water, photoelectrocatalytic oxidation method has attracted much attention in recent years. This report examined the feasibility of degrading ciprofloxacin and sulfamethoxazole through photoelectrocatalytic oxidation using FTO-BiVO4/Ag2S with p-n heterojunction as anode. BiVO4/Ag2S was prepared through electrodeposition and successive ionic layer adsorption/reaction on FTO glass. Structural and morphological studies using XRD, SEM, EDS and diffusive reflectance UV-Vis confirmed the successful construction of p-n heterojunction of BiVO4/Ag2S. Electrochemical techniques were used to investigate enhanced charge separation in the binary electrode. The FTO-BiVO4/Ag2S electrode exhibited the highest photocurrent response (1.194 mA/cm-2) and longest electron lifetime (0.40 ms) than both pristine BiVO4 and Ag2S electrodes which confirmed the reduction in recombination of charge carriers in the electrode. Upon application of the prepared FTO-BiVO4/Ag2S in photoelectrocatalytic removal of ciprofloxacin and sulfamethoxazole, percentage removal of 80% and 86% were achieved respectively with a low bias potential of 1.2 V (vs Ag/AgCl) within 120 min. The electrode possesses good stability and reusability. The results obtained revealed BiVO4/Ag2S as a suitable photoanode for removing recalcitrant pharmaceutical molecules in water.

Graphene oxide mediated co-generation of C-doping and oxygen defects in Bi2WO6 nanosheets: a combined DRIFTS and DFT investigation

In order to efficiently control air pollutants using photocatalytic technology, the co-generation of C-doping and oxygen vacancies (OVs) in Bi₂WO₆ (BWO) nanosheets was achieved by a graphene oxide (GO)-mediated hydrothermal method. The photocatalytic performance was highly improved with the synergistic effects of C-doping and OVs. The experimental characterization and DFT calculations were closely combined to reveal that the C element could serve as both an electron acceptor and channel for charge transfer to promote charge separation. Meanwhile, the OVs could induce the formation of a defect level in the band gap which increases the production of ˙OH as the primary reactive species by introducing more light-generated holes into the valence band. Meanwhile, the OVs could enhance the generation of ˙O₂^- species via the promotion of O₂ adsorption and activation on the catalyst surface. Moreover, the reaction intermediates were monitored and the mechanism of photocatalytic NO oxidation was proposed based on in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The design concept of photocatalyst modification with C-doping and OVs could offer a novel strategy to enhance the performance for environmental applications.

The effective photocatalysis and antibacterial properties of AgBr/Ag2MoO4@ZnO composites under visible light irradiation

A novel Z-scheme AgBr/Ag₂MoO₄@ZnO photocatalyst was fabricated via a hydrothermal process and in situ growth method. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were used to determine the structure of the photocatalyst. The results showed that the composites were tightly connected by the (101) lattice plane of ZnO, the (222) plane of Ag₂MoO₄ and the (200) lattice plane of AgBr. Because of the strong redox activity and good separability of photoelectrons and holes induced by the Z-scheme structure, the photodegradation rate for ciprofloxacin (CIP) solution was 80.5% by the photocatalysis of 0.5 AgBr/Ag₂MoO₄@ZnO. In addition, more than 99.999% of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa cells were killed within 60 min. These results demonstrate that AgBr/Ag₂MoO₄@ZnO is a promising photocatalyst, which can be used in organic pollutant degradation and the photocatalytic antibacterial area.

Facile synthesis of hierarchically nanostructured bismuth vanadate: An efficient photocatalyst for degradation and detection of hexavalent chromium

Heterostructured nanomaterials can paid more significant attention in environmental safety for the detection and degradation/removal of hazardous toxic chemicals over a decay. Here, we report the preparation of hierarchically nanostructured shuriken like bismuth vanadate (BiVO₄) as a bifunctional catalyst for photocatalytic degradation and electrochemical detection of highly toxic hexavalent chromium (Cr(VI)) using the green deep eutectic solvent reline, which allows morphology control in one of the less energy-intensive routes. The SEM results showed a good dispersion of BiVO₄ catalyst and the HR-TEM revealed an average particle size of ca. 5-10 nm. As a result, the BiVO₄ exhibited good photocatalytic activity under UV-light about 95% reduction of Cr(VI) to Cr(III) was observed in 160 min. The recyclability of BiVO₄ catalyst exhibited an appreciable reusability and stability of the catalyst towards the photocatalytic reduction of Cr(VI). Also, the BiVO₄-modified screen printed carbon electrode (BiVO₄/SPCE) displayed an excellent electrochemical performance towards the electrochemical detection of Cr(VI). Besides, the BiVO₄/SPCE demonstrated tremendous electrocatalytic activity, lower linear range (0.01-264.5 μM), detection limit (0.0035 μM) and good storage stability towards the detection of Cr(VI). Importantly, the BiVO₄ modified electrode was also found to be a good recovery in water samples for practical applications.

Insights into the role of CuO in the CO2 photoreduction process

The CO2 photoreduction process to produce light hydrocarbons is known to be influenced by the presence of CuO nanoparticles, but the actual role of this material, whether as a catalyst or a reactant, has not yet been revealed. In this work, we investigate the role of CuO nanoparticles produced by a solvothermal method as a catalyst in CO2-saturated water reaction media under UV light, considering the effects of different electrolytes (Na2C2O4, KBrO3, and NaOH) and temperatures on nanoparticle phase and activity. The electrolyte strongly influenced product selectivity (NaOH led to evolution of CH4, Na2C2O4 to CO, and KBrO3 to O2) and induced CuO phase change. A long-term analysis of these processes indicated that during the initial steps, CuO acted as a reactant, rather than as a catalyst, and was converted to CuCO3.Cu(OH)2, while the as-converted material acted as a catalyst in CO2 photoreduction, with conversion values comparable to those reported in the literature.

A PW12/Bi2WO6 composite photocatalyst for enhanced visible light photocatalytic degradation of organic dye pollutants

Bi₂WO₆ and polyoxometalate nanocomposites exhibited superior photocatalytic performance for degradation of organic dye rhodamine B under visible light.

Understanding the multifunctionality in Cu-doped BiVO4 semiconductor photocatalyst

A visible light-induced, Cu-doped BiVO₄ photocatalyst was synthesized by a microwave hydrothermal method. The photocatalytic efficiency was investigated in the degradation of model water pollutants like Methylene Blue (dye) and ibuprofen (pharmaceuticals), as well as the inactivation of Escherichia coli (bacteria). The Cu-doped BiVO₄ samples showed better efficiency than undoped BiVO₄, and the 1wt.% Cu-doped BiVO₄ sample showed the best efficiency. The degradation of Methylene Blue reached 95%, while the degradation of ibuprofen reached 75%, and the inactivation of E. coli reached 85% in irradiation with visible light. The appearance of additional absorption band shoulders and widening of the optical absorption in the visible range makes the prepared powder an efficient visible light-driven photocatalyst. Moreover, the formation of an in-gap energy state just above the valance band as determined by density functional theory (DFT) first principle calculation, facilitates the wider optical absorption range of the doped system. Similarly, this in-gap energy state also acts as an electron trap, which is favorable for the efficient separation and photoexcited charge carriers' transfer process. The formation of oxygen vacancies due to doping also improved the separation of the charge carrier, which promoted the trapping of electrons and inhibited electron hole recombination, thus increasing the photocatalytic activity. No decrease in the efficiency of the 1wt.% Cu-doped BiVO₄ photocatalyst in the degradation of ibuprofen over three consecutive cycles revealed the stability of the photocatalyst towards photocorrosion. These findings highlight the multifunctional applications of Cu-doped BiVO₄ in wastewater containing multiple pollutants.

Oxygen vacancy regulation in Nb-doped Bi2WO6 for enhanced visible light photocatalytic activity

Novel Nb-doped Bi₂WO₆ nanosheets have been successfully synthesized by a simple hydrothermal method.

Enhanced Peroxidase-Like Activity of MoS₂ Quantum Dots Functionalized g-C₃N₄ Nanosheets towards Colorimetric Detection of H₂O₂

MoS₂ quantum dots (QDs) functionalized g-C₃N₄ nanosheets (MoS₂@CNNS) were prepared through a protonation-assisted ion exchange method, which were developed as a highly efficient biomimetic catalyst. Structural analysis revealed that uniformly-dispersed MoS₂ QDs with controllable size and different loading amount grew in-situ on the surface of CNNS, forming close-contact MoS₂@CNNS nanostructures and exhibiting distinct surface properties. Compared to MoS₂ QDs and CNNS, the MoS₂@CNNS nanocomposites exhibited a more than four times stronger peroxidase-like catalytic activity, which could catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H₂O₂ to generate a blue oxide. Among the MoS₂@CNNS nanocomposites, MoS₂@CNNS(30) was verified to present the best intrinsic peroxidase-like performance, which could be attributed to the more negative potential and larger specific surface area. A simple, rapid and ultrasensitive system for colorimetric detection of H₂O₂ was thus successfully established based on MoS₂@CNNS, displaying nice selectivity, reusability, and stability. The detection limit of H₂O₂ could reach as low as 0.02 μM. Furthermore, the kinetic and active species trapping experiments indicated the peroxidase-like catalytic mechanism of MoS₂@CNNS. This work develops a novel, rapid, and ultrasensitive approach for visual assay of H₂O₂, which has a potential application prospect on clinical diagnosis and biomedical analysis.

Enhancement in the photocatalytic antifouling efficiency over cherimoya-like InVO4/BiVO4 with a new vanadium source

The problem of marine life attachment and its pollution to facilities has caused a lot of great troubles in the development and application of marine resources. The holes generated by the photocatalytic coating materials under sunlight may produce strong oxidizing species and showed a significant effect on the degradation and bactericidal performance of environmental organic matter. In this paper, a novel bismuth vanadate/indium vanadate (BiVO₄/InVO₄) composite with cherimoya-like microstructure was fabricated using new vanadium source. It is found that the composite materials showed enhanced photocatalytic antifouling property. The degradation efficiency of the model pollutes (Rhodamine B, RhB) achieved 99.775% within 280 min over BiVO₄/InVO₄ nanostructures, and the sterilization rate of E. coli, S. aureus, P. aeruginosa and A. carterae achieved 99.7148%, 99.5519%, 99.5411% and 96.00%, respectively. Moreover, the circulate photocatalytic degradation of antibacteria experiments demonstrated the outstanding stability and reusability of BiVO₄/InVO₄ composite. According to the active free radical trapping experiments, the hydroxyl radical (OH) and superoxide radical (O^2-) were certified to be the main reactive oxygen species in the BiVO₄/InVO₄ system. The distinctly enhanced photocatalytic performance of BiVO₄/InVO₄ nanomaterial primarily resulted from the narrow bandgap (about 1.86 eV). This study not only provides a new method for developing novel antibacterial materials, but also introduces a visible light-driven photocatalyst for water treatment and marine antifouling, especially for red tide control.

Near infrared light activatable PEI-wrapped bismuth selenide nanocomposites for photothermal/photodynamic therapy induced bacterial inactivation and dye degradation

Inactivation of bacteria and degradation of organic pollutants by engineered nanomaterials (NMs) are very effective approaches in producing safe and clean drinking water.

Highly efficient BiVO4 single-crystal photocatalyst with selective Ag2O-Ag modification: orientation transport, rapid interfacial transfer and catalytic reaction

Highly efficient Ag₂O-Ag/BiVO₄ single-crystal photocatalyst: (1) orientation transport, (2) rapid interfacial transfer and (3) catalytic reaction.

Nanostructured shuriken-like BiVO4 with preferentially exposed {010} facets: preparation, formation mechanism, and enhanced photocatalytic performance

The synthesis, formation mechanism, and application of nanostructured shuriken-like BiVO₄ with preferentially exposed {010} facets have been reported.

Preparation of Z-scheme AgI/Bi5O7I plate with high visible light photocatalytic performance by phase transition and morphological transformation of BiOI microspheres at room temperature

Z-scheme AgI/Bi₅O₇I plate composite fabricated at room temperature through phase transition and morphological transformation process with high photocatalytic activity.