Search Results (56)

The natural sunlight driven photocatalytic degradation of organic pollutants is a sustainable solution for water purification. The use of heterojunction nanocomposites in this process shows promise for improved photodegradation efficiency. In this work, nanocrystalline Zn₂SnO₄/SnO₂ obtained by the solid-state synthesis method was tested as a heterojunction photocatalyst material for the degradation of methylene blue (MB) and Rhodamine B (RhB) dyes as single and multicomponent systems in natural sunlight. Characterization of the structure and morphology of the synthesized nanocomposite using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDS), and photoluminescence (PL) spectroscopy confirmed the formation of Zn₂SnO₄/SnO₂ and heterojunctions between Zn₂SnO₄ and the SnO₂ nanoparticles. A photodegradation efficiency of 99.1% was achieved in 120 min with 50 mg of the photocatalyst for the degradation of MB and 70.6% for the degradation of RhB under the same conditions. In the multicomponent system, the degradation efficiency of 97.9% for MB and 53.2% for RhB was obtained with only 15 mg of the photocatalyst. The degradation of MB occurred through N-demethylation and the formation of azure intermediates and degradation of RhB occurred through sequential deethylation and fragmentation of the xanthene ring, both in single and multicomponent systems. Full article

Both tungsten trioxide (WO₃) nanosheet arrays and tungsten trioxide/zinc oxide (WO₃/ZnO) nanocomposites were grown on fluorine-doped tin oxide (FTO) coated glass slides using a hydrothermal method to develop a visible-light-driven photocatalyst with easy reusability. Field emission scanning electron microscopy (FE-SEM) observations confirmed the formation of irregular oxide nanosheet arrays on the FTO surfaces. X-ray diffraction (XRD) analysis revealed the presence of hexagonal WO₃ and wurtzite ZnO crystal phases. UV-Vis diffuse reflectance spectroscopy showed that integrating ZnO nanostructures with WO₃ nanosheets resulted in a blue shift of the absorption edge and a reduced absorption capacity in the visible-light region. Photoluminescence (PL) spectra indicated that the WO 0.5/ZnO 2.0 sample exhibited the lowest electron-hole recombination rate among the WO₃/ZnO nanocomposite sample. Photocatalytic degradation tests demonstrated that all WO₃/ZnO nanocomposite samples had higher photodegradation rates for a 10 ppm methylene blue (MB) aqueous solution under visible-light irradiation compared to pristine WO₃ nanosheet arrays. Among them, the WO 0.5/ZnO 2.0 sample showed the highest photocatalytic efficiency. Furthermore, it exhibited excellent recyclability and high photodegradation stability over three cycles. Full article

This research aims to analyze the improvement in the photocatalytic properties of ZnO nanoparticles by incorporating Gd. In order to understand the influence of incorporating Gd into the ZnO matrix, the photocatalytic activity of the material is compared at various Gd concentrations. Different doping concentrations of Gd ranging from 0 to 0.075 are incorporated into ZnO and the synthesized ZnO-Gd nanocomposites are investigated using structural, morphological, and optical analyses using XRD, SEM, and UV-vis spectroscopy, respectively. The photocatalytic performance of the synthesized ZnO-Gd nanocomposites is determined via the degradation of organic contaminants under visible light. Regarding the latter, the results suggest that photocatalytic efficiency increases with increasing Gd doping levels up to an optimal doping concentration. The enhancement of the photocatalytic performance of Gd-doped ZnO is explained, along with the mechanism related to the availability of new pathways for charge carrier recombination. Among all of them, the 0.075 Gd-doped ZnO catalyst exhibits the highest photocatalytic activity which degrades 89% of MB dye after being irradiated with UV light for 120 min. However, pure ZnO degrades only 40% of MB dye within the same testing conditions. In closing, this work confirms the applicability of Gd-doped ZnO nanocomposites as photocatalysts in cleaning up the environment and in wastewater treatment. Full article

Graphitic carbon nitride (g-C₃N₄) and zinc oxide (ZnO) are two promising materials that have been extensively studied for their potential applications in the photocatalytic and biomedical fields, including biosensors, bioimaging, photodynamic therapy, and antimicrobials, because of its biocompatible nature. The synthesis of g-C₃N₄/ZnO nanocomposites will be achieved through hydrothermal synthesis to produce materials with enhanced photocatalytic and biomedical properties due to the development of heterojunctions. The synthesized g-C₃N₄/ZnO hybrid nanostructures have a band gap of around 2.85 eV to 3.01 eV. The photocatalytic activity of the composites is evaluated through the degradation of organic pollutants (MB, RB171, RhB dyes) under simulated solar irradiation, demonstrating their potential for environmental remediation. In biomedical applications, the g-C₃N₄/ZnO nanocomposites exhibit biocompatibility and are explored for use in antimicrobial coatings. Techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and UV–Vis(ultra-violet visible) spectroscopy are employed to analyze the crystal structure, surface morphology, particle size, chemical composition, and optical properties of the composites. The comprehensive characterization of these materials is crucial for their successful development and utilization in various technological domains. Full article

Wastewater contaminated with dyes from the textile industry has been at the forefront in the last few decades, thus, it is imperative to find treatment methods that are safe and efficient. In this study, C. benghalensis plant extracts were used to synthesise by mass 20 mg/80 mg zinc oxide–carbon spheres (20/80 ZnO–CSs) nanocomposites, and the incorporation of the nanocomposites with 1% silver (1% Ag–ZnO–CSs) and 1% gold (1% Au–ZnO–CSs) was conducted. The impact of Ag and Au dopants on the morphological, optical, and photocatalytic properties of these nanocomposites in comparison to 20/80 ZnO–CSs was investigated. TEM, XRD, UV-vis, FTIR, TGA, and BET revealed various properties for these nanocomposites. TEM analysis revealed spherical particles with size distributions of 40–80 nm, 50–200 nm, and 50–250 nm for 1% Ag–ZnO–CSs, 1% Au–ZnO–CSs, and 20/80 ZnO–CSs, respectively. XRD data showed peaks corresponding to Ag, Au, ZnO, and CSs in all nanocomposites. TGA analysis reported a highly thermally stable material in ZnO-CS. The photocatalytic testing showed the 1% Au–ZnO–CSs to be the most efficient catalyst with a 98% degradation for MB textile dye. Moreover, 1% Au–ZnO–CSs also exhibited high degradation percentages for various pharmaceuticals. The material could not be reused and the trapping studies demonstrated that both OH• radicals and the e⁻ play a crucial role in the degradation of the MB. The photocatalyst in this study demonstrated effectiveness and high flexibility in degrading diverse contaminants. Full article

The use of a combination of nanoparticles as antimicrobial agents can be one strategy to overcome the tendency of microbes to become resistant to antibiotic action. Also, the optimization of nano-photocatalysts to efficiently remove persistent pollutants from wastewater is a hot topic. In this study, two composites ZnO/Au (1% wt.) and ZnO/Ag (1% wt.) were synthesized by simple aqueous solution methods. The structure and morphology of the r nanocomposites were analyzed by structural and optical characterization methods. The formation of AuNPs and AgNPs in these experiments was also discussed. The antimicrobial properties of ZnO, ZnO/Au, and ZnO/Ag nanomaterials were investigated against Gram-negative bacteria (Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus). The results showed an increase of 80% in the antimicrobial activity of ZnO/Au against Pseudomonas aeruginosa compared with 30% in the case of ZnO/Ag. Similarly, in the case of the S. aureus strain tests, ZnO/Au increased the antimicrobial activity by 55% and ZnO/Ag by 33%. The photocatalytic tests indicated an improvement in the photocatalytic degradation of methylene blue (MB) under UV irradiation using ZnO/Au and ZnO/Ag nanocomposites compared to bare ZnO. The photocatalytic degradation efficiency of ZnO after 60 min of UV irradiation was ∼83%, while the addition of AuNPs enhanced the degradation rate to ∼95% (ZP2), and AgNP presence enhanced the efficiency to ∼98%. The introduction of noble metallic nanoparticles into the ZnO matrix proved to be an effective strategy to increase their antimicrobial activity against P. aeruginosa and S. aureus, and their photocatalytic activity was evaluated through the degradation of MB dye. Comparing the enhancing effects of Au and Ag, it was found that ZnO/Au was a better antimicrobial agent while ZnO/Ag was a more effective photocatalyst under UV irradiation. Full article

The aim of this work was to biosynthesize SnO₂-decorated ZnO (ZT) nanocomposites (NCs) of different Sn content (10, 20, and 30 mol%), namely, ZT10, ZT20, and ZT30, using Olea europaea leaf aqueous extract-based phytocompounds as nanoparticle facilitating agents for application as effective photocatalyst in the removal of dyes from polluted water. The obtained ZT NCs were characterized using various techniques, including FTIR, XRD, TGA, TEM, EDS, UV–Vis, PL, and BET surface area. X-ray diffraction patterns show that rutile SnO₂ and hexagonal ZnO coexist in the composites, and their crystallite size (D) is affected by the SnO₂ ratio; the obtained D-values were 17.24, 19.07, 13.99, 6.45, and 12.30 nm for ZnO, SnO₂, ZT10, ZT20, and ZT30, respectively. The direct band gaps of the ZT heterostructure increase with increasing SnO₂ ratio (band gap = 3.10, 3.45, 3.14, 3.17, and 3.21 eV, respectively). TEM spectroscopy revealed nanorod and spherical grain morphologies of the composites, while EDS confirmed the elemental composition, the element ratio, and the composite’s purity. All catalysts exhibit type III isotherm with macropore structure. The photocatalytic efficiency against cationic (methylene blue (MB), rhodamine B (RB)), and anionic (methyl orange (MO)) dyes, under sunlight, was optimal with ZT20. The results revealed almost complete degradation at 55, 65, and 55 min, respectively. Hence, it is evident that incorporating SnO₂ improves the photocatalyst’s performance, with an apparent optimal enhancement at 20 mol% Sn decorating ZT NCs. More interestingly, the catalyst stability and activity remained unaffected even after four activating cycles. Full article

Dyes are toxic organic compounds released as effluent from various industries that need proper treatment as they pose serious hazards to the environment and living beings, including humans. Nanocomposites can be employed as photocatalysts for the elimination of such organic compounds from wastewater. One such attempt is made in this present research study, where a zinc-based nanocomposite has been fabricated for the elimination of the methylene blue dye (MB). For the development of nanocomposite, zinc oxide nanoparticles (ZnONPs) were prepared to utilize Allium sativa peel (garlic skin) extract, which was further processed to develop ZnO/kaolin clay NC. ZnONPs and ZnO/kaolin clay NC formation have been confirmed by UV–Vis spectral bands at 379 nm and 423 nm. The NC was rod-shaped, with width of 60–100 nm and length of 200–800 nm and an average size of 50.0 ± 0.58 nm. Both materials were compared for their efficacy in photocatalytic degradation of the MB under solar light irradiation. ZnONPs removed 65% of MB, whereas the degradation efficiency of ZnO/clay NC was calculated to be 96% for 10 ppm MB. A kinetics study for photocatalytic degradation of MB using both nanomaterials showed that the photocatalytic degradation followed the pseudo-first-order (PFO) type of reaction. This investigation represents an expeditious, lucrative, ecological, and appropriate technique for the fabrication of functional nanomaterials for the remediation of diverse organic pollutants. Full article

The biological synthesis of nanocomposites has become cost-effective and environmentally friendly and can achieve sustainability with high efficiency. Recently, the biological synthesis of semiconductor and metal-doped semiconductor nanocomposites with enhanced photocatalytic degradation efficiency, anticancer, and antibacterial properties has attracted considerable attention. To this end, for the first time, we biosynthesized zinc oxide (ZnO) and silver/ZnO nanocomposites (Ag/ZnO NCs) as semiconductor and metal-doped semiconductor nanocomposites, respectively, using the cell-free filtrate (CFF) of the bacterium Lysinibacillus sphaericus. The biosynthesized ZnO and Ag/ZnO NCs were characterized by various techniques, such as ultraviolet-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The photocatalytic degradation potential of these semiconductor NPs and metal-semiconductor NCs was evaluated against thiazine dye, methylene blue (MB) degradation, under simulated solar irradiation. Ag/ZnO showed 90.4 ± 0.46% photocatalytic degradation of MB, compared to 38.18 ± 0.15% by ZnO in 120 min. The cytotoxicity of ZnO and Ag/ZnO on human cervical HeLa cancer cells was determined using an MTT assay. Both nanomaterials exhibited cytotoxicity in a concentration- and time-dependent manner on HeLa cells. The antibacterial activity was also determined against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus). Compared to ZnO, Ag/ZnO NCs showed higher antibacterial activity. Hence, the biosynthesis of semiconductor nanoparticles could be a promising strategy for developing hybrid metal/semiconductor nanomaterials for different biomedical and environmental applications. Full article

Environmental and human health are seriously threatened by organic dye pollution. Many efforts have been made to find effective and safe methods of eliminating these contaminants. To mitigate these effects, the hydrothermal method was used to effectively generate a ternary kind of Dy₂WO₆-ZnO embedded in graphene oxide (DWZG) nanocomposites, which were used to degrade the pollutant. Powder X-ray diffraction (XRD) investigation confirms the crystalline character of the as-prepared DWZG nanocomposite. The Dy₂WO₆-ZnO composition on the graphene oxide (GO) layer is shaped like a combination of algae (Dy₂WO₆) and clusters (ZnO), as shown by scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) investigation revealed the composition of elements and oxidation state of C, Dy, O, W and Zn elements. Methylene blue (MB) was chosen as the organic dye target for photocatalytic degradation using the produced nanocomposites. MB is degraded with a photocatalytic efficiency of 98.2% in about 30 min using a DWZG catalyst. Based on the result of the research entitled “Reactive Oxidative Species,” the primary reactive species involved in the MB degradation are photo-generated ^•OH and O₂^•− radicals. The recycle test was also successful in evaluating the catalysts’ long-term viability as well as their reusability. Full article

Heterogeneous photocatalysis has been studied with various semiconductor materials for the efficient degradation of various water pollutants; however, there is the challenge of wide-bandgap photocatalyst materials, which limits their application under visible-light irradiation. Herein, a ZnO@MgO core–shell nanocomposite was synthesized using co-precipitation and applied to the photocatalytic degradation of MB dye under visible-light irradiation. MB degradation was optimized using the response surface methodology, resulting in 95.948% and ≈91% predicted and actual MB removals, respectively, at a 10 mg/L MB concentration, 1000 mg/L catalyst dose, pH 10, and time of 115.7 min. The degradation kinetics were studied, and it was found that the degradation followed pseudo-first-order kinetics with a rate constant of k = 0.07593 min⁻¹. A cost–benefit analysis was undertaken, and the operating costs were estimated based on the optimized conditions at $7.6/m³ with a payback period of 3.2 years. Full article

Robust hybrid g-C₃N₄/ZnO-W/Co_x heterojunction composites were synthesized using graphitic carbon nitride (g-C₃N₄) and ZnO-W nanoparticles (NPs) and different concentrations of Co dopant. The hybrid heterojunction composites were prepared by simple and low-cost coprecipitation methods. The fabricated catalyst was explored and investigated using various characterization techniques such as FTIR, XRD, FESEM and EDX. The surface morphology of the as-prepared hybrid nanocomposites with particle sizes in the range of 15–16 nm was validated by SEM analysis. The elemental composition of the synthesized composites was confirmed by EDS analysis. Photocatalysis using a photon as the sole energy source is considered a challenging approach for organic transformations under ambient conditions. The photocatalytic activity of the heterojunctions was tested by photodegrading methylene blue (MB) dye in the presence of sunlight. The reduced band gap of the heterojunction composite of 3.22–2.28 eV revealed that the incorporation of metal ions played an imperative role in modulating the light absorption range for photocatalytic applications. The as-synthesized g-C₃N₄/ZnO-W/Co_0.010 composite suppressed the charge recombination ability during the photocatalytic degradation of methylene blue (MB) dye. The ternary heterojunction C₃N₄/ZnO-W/Co_0.010 composite showed an impressive photocatalytic performance with 90% degradation of MB under visible light within 90 min of irradiation, compared to the outcomes achieved with the other compositions. Lastly, the synthesized composites showed good recyclability and mechanical stability over five cycles, confirming them as promising photocatalyst options in the future. Full article

Here, we report a simple and versatile synthesis of low-dimensional ZnO nanosheet (NS) arrays modified with Fe₂O₃ (hematite) to assemble photocatalytic coatings and non-enzymatic glucose sensors. Photocatalytic coatings made of widespread elements (zinc and iron) were tested for methylene blue (MB) dye decolorization under ultraviolet and visible (UV-vis) irradiation. A comparative study of unmodified and modified ZnO NS photocatalysts revealed a significant decrease in the dye concentration in 180 min when ZnO/Fe₂O₃ arrays were used. Size dependence efficiency of the hematite layer deposited onto ZnO is presented. A study of the sensitivity of biosensors made of ZnO nanostructures and ZnO/Fe₂O₃ nanocomposites for glucose detection showed an improvement in sensitivity with increased Fe₂O₃ thickness. The structure and morphology of low-dimensional coatings were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). The optical properties of nanoarrays showed a red shift of absorption after modifying ZnO with hematite layers, which holds good promise for expanding photocatalytic activity in the visible region. Full article

In this study, successful synthesis of ZnO nanoparticles (NPs), CuO NPs, and ZnO/CuO nanocomposite through an eco-friendly method using Corriandrum sativum leaf extract as a capping agent is reported. Using XRD, FTIR, UV-Vis, and SEM techniques, the synthesized materials were characterized for structural analysis, functional groups identification, spectroscopic measurements, and morphological analysis. The percentage composition and purity of the samples were determined by using Energy Dispersive X-ray (EDX), which showed the synthesis of materials. Morphological analysis was done by Scanning Electron Microscopy (SEM) which reflected that the CuO NPs, ZnO NPs and ZnO/CuO nanocomposite were spherical, and the average size calculated by using Image J software was around 25 nm, 55 nm, and 11 nm, respectively. FTIR and UV-Vis analyses were used for synthetic confirmation through characteristic peaks of materials. The synthesized (ZnO, CuO, and CuO/ZnO) nanomaterials were evaluated for photocatalytic activity using methylene blue (MB) dye. Among all three photocatalysts, the composite showed maximum photodegradation compared to the other two materials. The present work could lead to a pathway for the decontamination of harmful dyes of wastewater released from different industries. Full article

In this paper, a facile hydrothermal approach was used to integrate graphitic carbon nitride dots (CNDs) with hetaerolite (ZnMn₂O₄) at different weight percentages. The morphology, microstructure, texture, electronic, phase composition, and electrochemical properties were identified by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), ultraviolet-visible diffuse reflectance (UV-vis DR), photoluminescence (PL), electrochemical impedance spectroscopy (EIS), Brunauer–Emmett–Teller (BET), Barrett–Joyner–Halenda (BJH), and photocurrent density. The results of XRD, FT-IR, EDX, and XPS analyses confirmed the synthesis of CNDs/ZnMn₂O₄ (20%) nanocomposite. As per PL, EIS, and photocurrent outcomes, the binary CNDs/ZnMn₂O₄ nanocomposite revealed superior features for interfacial transferring of charge carriers. The developed p–n heterojunction at the interface of CNDs and ZnMn₂O₄ nanoparticles partaken a significant role in the impressive charge segregation and migration. The binary nanocomposites were employed for the photodegradation of several dye pollutants, including rhodamine B (RhB), fuchsin, malachite green (MG), and methylene blue (MB) at visible wavelengths. Amongst the fabricated photocatalysts, the CNDs/ZnMn₂O₄ (20%) nanocomposite gave rise to about 98% RhB degradation efficiency within 45 min with the rate constant of 747 × 10⁻⁴ min⁻¹, which was 66.5-, 3.44-, and 2.72-fold superior to the activities of CN, CNDs, and ZnMn₂O₄ photocatalysts, respectively. The impressive photodegradation performance of this nanocomposite was not only associated with the capacity for impressive visible-light absorption and boosted separation and transport of charge carriers, but also with its large surface area. Full article