Designing of highly active g-C3N4/Ni-ZnO photocatalyst nanocomposite for the disinfection and degradation of the organic dye under sunlight radiations

Detection of toxic cypermethrin pesticides in drinking water by simple graphitic electrode modified with Kraft lignin@Ni@g-C3N4 nano-composite

The detrimental effects of widespread pesticide application on the health of living organisms highlight the urgent need for technological advancements in monitoring pesticide residues at trace levels. This study involves the synthesis of a distinctive sensing material, KL@Ni@g-C3N4, which comprises nanocomposites of graphitic carbon nitride with Kraft lignin and nickel. The prepared samples were characterized using FT-IR, PXRD, TEM, SEM, and EDX techniques. The KL@Ni@g-C3N4 nanocomposite was drop-cast on a graphite electrode. Subsequently, this fabricated electrode was used to detect cypermethrin (CYP) residues in drinking water. The redox properties of the fabricated sensors were evaluated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The limit of detection (LOD) of the fabricated sensor was determined to be 0.026 μg mL-1, which is below the maximum residual limits of CYP in the environment (0.5 μg mL-1) and within the acceptable range for food products (∼0.05 to 0.2 μg mL-1). Therefore, this study proposes a promising alternative to conventional methods for detecting pesticides in drinking water.

Cellulose acetate membranes loaded with WO3/g-C3N4: a synergistic approach for effective photocatalysis

The objective of this study is to develop an efficient, easily recoverable membrane-based photocatalyst for removing organic pollutants from aqueous solutions. This study documents the effective synthesis of a novel composite photocatalyst comprising WO3/g-C3N4(WCN) loaded onto cellulose acetate (CA). The physicochemical properties of the synthesized nanocomposites were validated using a range of techniques, including Fourier transform infrared spectroscopy, x-ray diffraction, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy, and UV-visible diffuse reflectance spectroscopy. SEM analysis revealed that the WCN particles exhibited a well-decorated arrangement on the CA surface in the form of spherical particles. The successfully synthesized film was utilized as a potential adsorbent for removing organic pollutants such as Rhodamine B (Rh-B) and Methylene blue (MB) from aqueous solutions under UV light illumination. The results showcased the significant potential of the WCN@CA nanocomposite, achieving a remarkable 83% and 85% efficiency in eliminating Rh-B and MB. The pseudo-first-order kinetic models were found to be appropriate for both dye adsorption onto the WCN@CA nanocomposite. The WCN@CA catalyst, capable of being reused five times without significant loss of efficiency, shows great potential for decomposing toxic organic pollutants. The novelty of this work lies in the innovative combination of WCN with CA, resulting in a highly efficient and reusable photocatalyst for environmental remediation.

Tecoma stans floral extract-mediated synthesis of MgFe2O4/ZnO nanoparticles for adsorption and photocatalytic degradation of coomassie brilliant blue dye

Toxic organic dyes-containing wastewater treatment by adsorption and photocatalytic techniques is widely applied, but adsorbents and photocatalysts are often synthesized through chemical methods, leading to secondary pollution by released chemicals. Here, we report a benign method using Tecoma stans floral extract to produce MgFe2O4/ZnO (MGFOZ) nanoparticles for adsorption and photocatalytic degradation of coomassie brilliant blue (CBB) dye. Green MGFOZ owned a surface area of 9.65 m2/g and an average grain size of 54 nm. This bio-based nanomaterial showed higher removal percentage and better recyclability (up to five cycles) than green MgFe2O4 and ZnO nanoparticles. CBB adsorption by MGFOZ was examined by kinetic and isotherm models with better fittings of Bangham and Langmuir or Temkin. RSM-based optimization was conducted to reach an actual adsorption capacity of 147.68 mg/g. Moreover, MGFOZ/visible light system showed a degradation efficiency of 89% CBB dye after 120 min. CBB adsorption can be controlled by both physisorption and chemisorption while •O2- and •OH radicals are responsible for photo-degradation of CBB dye. This study suggested that MGFOZ can be a promising adsorbent and catalyst for removal of organic dyes in water.

Emerging aspects of metal ions-doped zinc oxide photocatalysts in degradation of organic dyes and pharmaceutical pollutants - A review

In recent periods, a broad assortment of continual organic contaminants has been released into our natural water resources. Indeed, it is exceedingly poisonous and perilous to living things; thus, the elimination of these organic pollutants before release into the water bodies is vital. A variety of techniques have been utilized to remove these organic pollutants with advanced oxidation photocatalytic methods with zinc oxide (ZnO) nanoparticles being commonly used as a capable catalyst for contaminated water treatment. Nevertheless, its broad energy gap, which can be only stimulated under an ultraviolet (UV) light source, and high recombination pairs of electrons and holes limit their photocatalytic behaviors. However, numerous methods have been suggested to decrease its energy gap for visible regions. Including, the doping ZnO with metal ions (dopant) can be considered as an effectual route not only the reason for a movement of the absorption edges toward the higher (visible light) region but also to lower the electron-hole pair (e--h+) recombination. This review concentrated on the impact of dissimilar types of metal ions (dopants) on the advancement in the degradation performance of ZnO. So, this work demonstrates a vital review of contemporary attainments in the alteration of ZnO nanoparticles for organic pollutants eliminations. Besides, the effect of doping ions including transition metals, rare earth metals, and metal ions (substitutional and interstitial) concerning numerous types of altered ZnO are summarized. The photodegradation mechanisms for pristine and metal-modified ZnO nanoparticles are also conferred.

Graphitic Carbon Nitride/Zinc Oxide-Based Z-Scheme and S-Scheme Heterojunction Photocatalysts for the Photodegradation of Organic Pollutants

Graphitic carbon nitride (g-C3N4), a metal-free polymer semiconductor, has been recognized as an attractive photocatalytic material for environmental remediation because of its low band gap, high thermal and photostability, chemical inertness, non-toxicity, low cost, biocompatibility, and optical and electrical efficiency. However, g-C3N4 has been reported to suffer from many difficulties in photocatalytic applications, such as a low specific surface area, inadequate visible-light utilization, and a high charge recombination rate. To overcome these difficulties, the formation of g-C3N4 heterojunctions by coupling with metal oxides has triggered tremendous interest in recent years. In this regard, zinc oxide (ZnO) is being largely explored as a self-driven semiconductor photocatalyst to form heterojunctions with g-C3N4, as ZnO possesses unique and fascinating properties, including high quantum efficiency, high electron mobility, cost-effectiveness, environmental friendliness, and a simple synthetic procedure. The synergistic effect of its properties, such as adsorption and photogenerated charge separation, was found to enhance the photocatalytic activity of heterojunctions. Hence, this review aims to compile the strategies for fabricating g-C3N4/ZnO-based Z-scheme and S-scheme heterojunction photocatalytic systems with enhanced performance and overall stability for the photodegradation of organic pollutants. Furthermore, with reference to the reported system, the photocatalytic mechanism of g-C3N4/ZnO-based heterojunction photocatalysts and their charge-transfer pathways on the interface surface are highlighted.

Photodegradation of fleroxacin by g-C3N4/PPy/Ag and HPLC-MS/MS analysis of degradation pathways

To improve the photocatalytic activity of g-C₃N₄, graphitic phase carbon nitride was prepared using melamine as the substrate and modified with PPy and Ag nanoparticles. The structure, morphology, and optical properties of the photocatalysts were investigated using various characterization methods such as XRD, FT-IR, TEM, XPS, and UV-vis DRS. The degradation of fleroxacin, a common quinolone antibiotic, was isolated and measured using the HPLC-MS/MS technique to trace its intermediates and deduce the main degradation pathways. The results showed that g-C₃N₄/PPy/Ag had high photocatalytic activity and a degradation rate of more than 90%. The fleroxacin degradation reactions were primarily oxidative ring opening of the N-methyl piperazine ring structure, defluorination reactions on fluoroethyl, HCHO, and N-methyl ethylamine removal reactions.

Facile Fabrication of Highly Active CeO2@ZnO Nanoheterojunction Photocatalysts

Photocatalyst performance is often limited by the poor separation and rapid recombination of photoinduced charge carriers. A nanoheterojunction structure can facilitate the separation of charge carrier, increase their lifetime, and induce photocatalytic activity. In this study, CeO₂@ZnO nanocomposites were produced by pyrolyzing Ce@Zn metal-organic frameworks prepared from cerium and zinc nitrate precursors. The effects of the Zn:Ce ratio on the microstructure, morphology, and optical properties of the nanocomposites were studied. In addition, the photocatalytic activity of the nanocomposites under light irradiation was assessed using rhodamine B as a model pollutant, and a mechanism for photodegradation was proposed. With the increase in the Zn:Ce ratio, the particle size decreased, and surface area increased. Furthermore, transmission electron microscopy and X-ray photoelectron spectroscopy analyses revealed the formation of a heterojunction interface, which enhanced photocarrier separation. The prepared photocatalysts show a higher photocatalytic activity than CeO₂@ZnO nanocomposites previously reported in the literature. The proposed synthetic method is simple and may produce highly active photocatalysts for environmental remediation.

Designing Highly Active S-g-C3N4/Te@NiS Ternary Nanocomposites for Antimicrobial Performance, Degradation of Organic Pollutants, and Their Kinetic Study

The current research is about the synthesis of pure nickel sulfide, a series of Te (0, 0.5, 1, 1.5, 2, and 3 wt.%)-doped NiS (Te@NiS) nanoparticles (NPs), and a series of S-g-C3N4 (10, 30, 50, 70, and 80 wt.%)/Te@NiS nanocomposites (NCs), fabricated through a hydrothermal route. XRD and FTIR spectroscopic techniques demonstrated the successful synthesis of NPs and NCs. SEM-EDX images confirmed the flakelike structure and elemental constituents of the fabricated materials. Tauc plots were drawn, to calculate the band gaps of the synthesized samples. Te doping resulted in a significant reduction in the band gap of the NiS NPs. The photocatalytic efficiency of the NPs and NCs was investigated against MB, under sunlight. The results obtained for the photocatalytic activity, showed that 1%Te@NiS nanoparticles have an excellent dye degradation capacity in sunlight. This was made even better by making a series of SGCN/1% Te@NiS nanocomposites with different amounts of S-g-C3N4. When compared to NiS, Te@NiS, SGCN, and 70%SGCN/1%Te@NiS, the 70%SGCN/1%Te@NiS NCs have excellent antifungal ability. The higher impact of SGCN/Te@NiS, may be due to its enhanced ability to disperse and interact with the membranes and intracellular proteins of fungi. The 70%SGCN/1%Te@NiS NCs showed excellent antibacterial and photocatalytic efficiency. Thus, the 70%SGCN/1%Te@NiS NCs might prove fruitful in antibacterial and photocatalytic applications.

Synthesis and applications of graphitic carbon nitride (g-C3N4) based membranes for wastewater treatment: A critical review

Semiconducting membrane combined with nanomaterials is an auspicious combination that may successfully eliminate diverse waste products from water while consuming little energy and reducing pollution. Creating an inexpensive, steady, flexible, and diversified business material for membrane production is a critical challenge in membrane technology development. Because of its unusual structure and high catalytic activity, graphitic carbon nitride (g-C3N4) has come out as a viable material for membranes. Furthermore, their great durability, high permanency under challenging environments, and long-term use without decrease in flux are significant advantages. The advanced material techniques used to manage the molecular assembly of g-C3N4 for separation membrane were detailed in this review work. The progress in using g-C3N4-based membranes for water treatment has been detailed in this presentation. The review delivers an updated description of g-C3N4 based membranes and their separation functions and new ideas for future enhancements/adjustments to address their weaknesses in real-world situations. Finally, the ongoing problems and promising future research directions for g-C3N4-based membranes are discussed.

Integration of Mn-ZnFe2O4 with S-g-C3N4 for Boosting Spatial Charge Generation and Separation as an Efficient Photocatalyst

The disposal of dyes and organic matter into water bodies has become a significant source of pollution, posing health risks to humans worldwide. With rising water demands and dwindling supplies, these harmful compounds must be isolated from wastewater and kept out of the aquatic environment. In the research presented here, hydrothermal synthesis of manganese-doped zinc ferrites’ (Mn-ZnFe₂O₄) nanoparticles (NPs) and their nanocomposites (NCs) with sulfur-doped graphitic carbon nitride (Mn-ZnFe₂O₄/S-g-C₃N₄) are described. The samples’ morphological, structural, and bonding features were investigated using SEM, XRD, and FTIR techniques. A two-phase photocatalytic degradation study of (0.5, 1, 3, 5, 7, 9, and 11 wt.%) Mn-doped ZnFe₂O₄ NPs and Mn-ZnFe₂O₄/(10, 30, 50, 60, and 70 wt.%) S-g-C₃N₄ NCs against MB was carried out to find the photocatalyst with maximum efficiency. The 9% Mn-ZnFe₂O₄ NPs and Mn-ZnFe₂O₄/50% S-g-C₃N₄ NCs exhibited the best photocatalyst efficiency in phase one and phased two, respectively. The enhanced photocatalytic activity of the Mn-ZnFe₂O₄/50% S-g-C₃N₄ NCs could be attributed to synergistic interactions at the Mn-ZnFe₂O₄/50% S-g-C₃N₄ NCs interface that resulted in a more effective transfer and separation of photo-induced charges. Therefore, it is efficient, affordable, and ecologically secure to modify ZnFe₂O₄ by doping with Mn and homogenizing with S-g-C₃N₄. As a result, our current research suggests that the synthetic ternary hybrid Mn-ZnFe₂O₄/50% S-g-C₃N₄ NCs may be an effective photocatalytic system for degrading organic pollutants from wastewater.

Construction of a Well-Defined S-Scheme Heterojunction Based on Bi-ZnFe2O4/S-g-C3N4 Nanocomposite Photocatalyst to Support Photocatalytic Pollutant Degradation Driven by Sunlight

Currently, organic dyes and other environmental contaminants are focal areas of research, with considerable interest in the production of stable, high-efficiency, and eco-friendly photocatalysts to eliminate these contaminants. In the present work, bismuth-doped zinc ferrite (Bi-ZnFe2O4) nanoparticles (NPs) and bismuth-doped zinc ferrites supported on sulfur-doped graphitic carbon nitride (Bi-ZnFe2O4/S-g-C3N4) (BZFG) photocatalysts were synthesized via a hydrothermal process. SEM, XRD, and FTIR techniques were used to examine the morphological, structural, and bonding characteristics of the synthesized photocatalysts. The photocatalytic competence of the functional BZFG nanocomposites (NCs) was studied against MB under sunlight. The influence of Bi (0.5, 1, 3, 5, 7, 9, and 11 wt.%) doping on the photocatalytic performance of ZnFe2O4 was verified, and the 9%Bi-ZnFe2O4 nanoparticles exhibited the maximum MB degradation. Then, 9%Bi-ZnFe2O4 NPs were homogenized with varying amounts of S-g-C3N4 (10, 30, 50, 60, and 70 wt.%) to further enhance the photocatalytic performance of BZFG NCs. The fabricated Bi-ZnFe2O4/30%S-g-C3N4 (BZFG-30) composite outperformed ZnFe2O4, S-g-C3N4 and other BZFG NCs in terms of photocatalytic performance. The enriched photocatalytic performance of the BZFG NCs might be ascribed to a more efficient transfer and separation of photo-induced charges due to synergic effects at the Bi-ZnFe2O4/S-g-C3N4 interconnection. The proposed modification of ZnFe2O4 using Bi and S-g-C3N4 is effective, inexpensive, and environmentally safe.

Boosted spatial charge carrier separation of binary ZnFe2O4/S-g-C3N4 heterojunction for visible-light-driven photocatalytic activity and antimicrobial performance

A potential method for removing toxins from contaminated wastewater, especially organic pollutants, is photo-catalysis. Here, a simple technique for producing zinc ferrite nanoparticles (ZnFe2O4 NPS) with varying quantities of sulphur doped graphitic carbon nitride nanocomposites (ZnFe2O4/S-g-C3N4 NCs) has been described. Then, using X-ray diffraction (XRD), TEM, EDX, XPS, photocurrent response, EIS, and Fourier Transform Infrared spectroscopy (FT-IR), the photo-catalytic activity of the produced nanoparticles (NPs) and nanocomposites (NCs) was examined and evaluated. The photo-catalytic activity of ZnFe2O4/S-g-C3N4 NCs was compared to a model pollutant dye, methylene blue, while degradation was evaluated spectrophotometrically (MB). Solar light has been used through irradiation as a source of lighting. The photocatalytic behaviour of the ZnFe2O4/S-g-C3N4 NCs photocatalyst was superior to that of genuine ZnFe2O4 and S-g-C3N4, which was attributed to synergic effects at the ZnFe2O4/S-g-C3N4 interconnection. Antimicrobial activity of ZnFe2O4/S-g-C3N4 against Gram-positive and Gram-negative bacteria under visible light was performed. In addition, these ZnFe2O4/S-g-C3N4 NCs show a lot of promise as an antibacterial agent.

Fabrication of polyamide-12/cement nanocomposite and its testing for different dyes removal from aqueous solution: characterization, adsorption, and regeneration studies

Polyamide-12/Portland cement nanocomposite was prepared by using the exfoliated adsorption method. The fabricated nanocomposite was applied first time to remove Congo red (CR), brilliant green (BG), methylene blue (MB), and methyl red (MR) from the synthetic wastewater. The polymer nanocomposite was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, elemental mapping, Brunauer-Emmett-Teller surface area analysis, and X-ray diffraction. The adsorption was rapid and all the studied dyes were absorbed on the surface of the polymer nanocomposite in 90 min. The point of zero charge was found at pH 5 and the factors such as pH, time, and temperature were found to affect the adsorption efficiency. Freundlich isotherm and pseudo-second-order models well-fitted the adsorption isotherm and kinetics data, respectively. The calculated maximum adsorption capacity was 161.63, 148.54, 200.40, and 146.41 mg/g for CR, BG, MB, and MR, respectively. The mode of the adsorption process was endothermic, spontaneous, and physical involving electrostatic attraction. On an industrial scale, the high percentage of desorption and slow decrease in the percentage of adsorption after every five regeneration cycles confirm the potential, practicality, and durability of the nanocomposite as a promising and advanced adsorbent for decolorization of colored wastewater.

A well-defined S-g-C3N4/Cu-NiS heterojunction interface towards enhanced spatial charge separation with excellent photocatalytic ability: synergetic effect, kinetics, antibacterial activity, and mechanism insights

A well-defined heterojunction among two dissimilar semiconductors exhibited enhanced photocatalytic performance owing to its capability for boosting the photoinduced electron/hole pair transportation. Therefore, designing and developing such heterojunctions using diverse semiconductor-based materials to enhance the photocatalytic ability employing various approaches have gained research attention. For this objective, g-C3N4 is considered as a potential photocatalytic material for organic dye degradation; however, the rapid recombination rate of photoinduced charge carriers restricts the widespread applications of g-C3N4. Henceforth, in the current study, we constructed a heterojunction of S-g-C3N4/Cu-NiS (SCN/CNS) two-dimensional/one-dimensional (2D/1D) binary nanocomposites (NCs) by a self-assembly approach. XRD results confirm the construction of 22% SCN/7CNS binary NCs. TEM analysis demonstrates that binary NCs comprise Cu-NiS nanorods (NRs) integrated with nanosheets (NSs) such as the morphology of SCN. The observed bandgap value of SCN is 2.69 eV; nevertheless, the SCN/CNS binary NCs shift the bandgap to 2.63 eV. Photoluminescence spectral analysis displays that the electron-hole pair recombination rate in the SCN/CNS binary NCs is excellently reduced owing to the construction of the well-defined heterojunction. The photoelectrochemical observations illustrate that SCN/CNS binary NCs improve the photocurrent to ∼0.66 mA and efficiently suppress the electron-hole pairs when compared with that of undoped NiS, CNS and SCN. Therefore, the 22% SCN/7CNS binary NCs efficiently improved methylene blue (MB) degradation to 99% for 32 min under visible light irradiation.

Designing a novel visible-light-driven heterostructure Ni-ZnO/S-g-C3N4 photocatalyst for coloured pollutant degradation

In this study, photocorrosion of ZnO is inhibited by doping Ni in the ZnO nanostructure and electron-hole recombination was solved by forming a heterostructure with S-g-C3N4. Ni is doped into ZnO NPs from 0 to 10% (w/w). Among the Ni-decorated ZnO NPs, 4% Ni-doped ZnO NPs (4NZO) showed the best performance. So, 4% Ni-ZnO was used to form heterostructure NCs with S-g-C3N4. NZO NPs were formed by the wet co-precipitation route by varying the weight percentage of Ni (0-10% w/w). Methylene blue (MB) was used as a model dye for photocatalytic studies. For the preparation of the 4NZO-x-SCN nanocomposite, 4NZO NPs were formed in situ in the presence of various concentrations of S-g-C3N4 (10-50% (w/w)) by using the coprecipitation route. The electron spin resonance (ESR) and radical scavenger studies showed that O2 - and OH free radicals were the main reactive species that were responsible for MB photodegradation.

Representative 2D-material-based nanocomposites and their emerging applications: a review

Composites (or complex materials) are formed from two or many constituent materials with novel physical or chemical characteristics when integrated. The individual components can be combined to create a unique composite material through mechanical transfer, physical stacking, exfoliation, derivative chemical mixtures, mixtures of solid solutions, or complex synthesis processes. The development of new composites based on emerging 2D nanomaterials has allowed for outstanding achievements with novel applications that were previously unknown. These new composite materials show massive potential in emerging applications due to their exceptional properties, such as being strong, light, cheap, and highly photodegradable, and their ability to be used for water splitting and energy storage compared to traditional materials. The blend of existing polymers and 2D materials with their nanocomposites has proven to be immediate solutions to energy and food scarcity in the world. Although much literature has been reported in the said context, we tried to provide an understanding about the relationship of their mechanisms and scope for future application in a comprehensive way. In this review, we briefly summarize the basic characteristics, novel physical and chemical behaviors, and new applications in the industry of the emerging 2D-material-based composites.

Multifunctional Ni–Mg bimetal-activated Zn(O,S) for hydrogen generation and environmental remediation with simulated solar-light irradiation

NMZ-S10 is a powerful and robust photocatalyst that is capable of conducting the hydrogen evolution reaction, chromium (Cr6+) reduction, mixed-dye degradation, and hydrogenation reaction under solar light illumination.