Sunlight Irradiation Research Articles

Cobalt titanate nanocatalyst for enhanced photodegradation of atrazine: kinetics, degradation efficiency, and mechanistic analysis

In this study, cobalt titanate nanoparticles (CoTiO₃ NPs) were synthesized and applied as a photocatalyst to degrade atrazine. Scanning electron microscopic (SEM) analysis showed irregularly shaped particles prone to agglomeration, while X-ray diffraction (XRD) confirmed the formation of a rhombohedral CoTiO₃ phase with a crystallite size of 3.76 nm. Raman spectroscopic analysis showed vibrations typical for Ti–O and Co–O bonds and confirmed a well-defined cobalt titanate structure. Thermogravimetric analysis (TGA) showed that the nanoparticles remained stable up to 800 °C. The photocatalytic activity of CoTiO₃ NPs was tested under sunlight irradiation and the results obtained demonstrated excellent efficiency compared to the photolysis reaction. The efficiency was influenced by concentration (20–50 ppm), catalyst dosage (0.5–2.0 mg/L), pH (4.21–10.22), and irradiation time (0–120 min). The synthesized nanoparticles exhibited a surface area of 32.5 m2/g (DFT) and 828.03 m⁻1 (BET), a pore volume of 0.03925 m3/g, and a bandgap energy of 2.66 eV. Kinetic studies demonstrated that the degradation followed the Langmuir–Hinshelwood model, with the photocatalytic reaction being the rate-determining step. Adsorption rate constants were found to range from 0.03828 to 0.166528 min⁻1, while photocatalytic rate constants ranged from 0.373692 to 0.977135 min⁻1. The CoTiO₃ NPs also showed excellent recyclability, maintaining high degradation efficiency after five cycles. Scavenger experiments confirmed that hydroxyl radicals (HO•) are responsible for atrazine degradation while GCMS analysis confirmed the complete mineralization of atrazine with carbon dioxide (CO₂) and water (H₂O) as the final degradation products.

Promoted Photocatalytic H2 Production of 0D/2D CeO2 Nanoparticles and N-Defects Graphitic Carbon Nitride S-Scheme Heterojunction.

Incorporating two-phase heterojunctions with matching band structures represents a promising strategy for developing photocatalysts with enhanced efficiency. This work prefers a novel approach that employs a template-assisted strategy based on a porous structured UCCN@CeO2 0D/2D S-scheme heterojunction. The proposed method aims to improve photocatalytic activity by harnessing the synergistic effects of monodispersed CeO2 nanoparticles and ultrathin N-defect CN nanosheets. The catalyst demonstrates a remarkable photocatalytic hydrogen evolution rate, reaching an impressive value of 5.59 mmol h-1 g-1 when subjected to simulated sunlight irradiation. Furthermore, the photocatalyst maintains a substantial activity level, yielding 2.35 mmol h-1 g-1 under visible light (≥400 nm). The significant improvement in the photocatalytic performance of the UCCN@CeO2 catalyst is attributed to the unique structural design and effective charge separation facilitated by the S-scheme mechanism. Kelvin probe force microscopy, theoretical calculations, and femtosecond transient absorption spectroscopy affirm the efficient charge transportation across the catalyst interface. Additionally, electron spin resonance spectroscopy measurements further support the charge transfer pathway in the S-scheme. This research presents an innovative approach for designing and developing CN-based catalysts featuring S-scheme heterojunctions, aiming to improve their efficiency and practical use in photocatalytic applications.

Highly Transparent, Spectrally Selective Power-Generating Windows Based on WO3-x Nanorods and Carbon Dots for Full-Spectrum Utilization.

Near-infrared (NIR) shielding windows can selectively regulate excess solar radiation to reduce heating and cooling energy consumption in a built environment. However, the dissipation of ultraviolet (UV) and visible light into waste heat is inevitable, leading to inefficient solar energy utilization. Herein, a tandem spectrally selective power-generating (SSPG) window is developed by incorporating oxygen-deficient tungsten oxide WO3-x nanorod-based NIR shielding windows and red-emissive carbon dot-based luminescent solar concentrators (LSCs) to realize full-spectrum utilization. Semitransparent NIR shielding modules absorb NIR light to reduce indoor thermal radiation, while a semitransparent LSC coupled with a photovoltaic system converts UV and partially visible light into electricity. The SSPG window exhibits a visible light transmittance of up to 70.44% and power conversion efficiency of 0.31%, while effectively reducing the indoor temperature by 7 °C under sunlight irradiation. In addition, this SSPG window has good thermal-/photostability and excellent NIR shielding performance after heat treatment and UV irradiation. This work may provide a new avenue for the development of energy-saving windows.

The design and preparation of PDI modified NH2-MIL-101(Fe) for high efficiency removal of dimethoate in peroxymonosulfate system: Performance, mechanism, pathway and toxicity assessment

The widespread use of organophosphorus pesticide dimethoate (DMT) in agriculture poses a threat to human health. In this work, the perylene tetracarboxylic diimide (PDI) modified NH2-MIL-101(Fe) (PDI/MIL) with strong covalent bond C(=O)–N were designed and prepared by a step solvothermal method. The synergistic effect between photocatalytic and peroxymonosulfate (PMS) activation for the DMT elimination over PDI/MIL was gained. Interestingly, PDI/MIL(1:10)/PMS showed boosting degradation efficiency (95.6%) for DMT under 18 min simulated sunlight irradiation. Its apparent reaction rate constant was 24.7 times higher than that of NH2-MIL-101(Fe)/PMS. Moreover, its reusability, stability and mineralization ability were evaluated, and a remarkable mineralization rate of 95.3% with 90 min was achieved. The enhanced activity were attributed to the formation of amide bond that exhibited superior charger transport ability and amount of produced active species. Combined the results obtained from the HPLC-MS and molecular structure characteristics of DMT analyzed by Fukui index, the degradation pathways were proposed. The toxicity of intermediates were predicted by Ecological Structure Activity Relationship (ECOSAR), Toxicity Estimation Software Tool (T.E.S.T.), and Vibrio fischeri experiments. Our work provided deep insights into the mechanisms of DMT degradation via photocatalysis-activated PMS over organic semiconductor modified metal organic frameworks.

Unveiling S-scheme charge migration mechanism in La2O3/g-C3N5 heterojunction for excellent photocatalytic H2 production under simulated sunlight irradiation

Unveiling S-scheme charge migration mechanism in La2O3/g-C3N5 heterojunction for excellent photocatalytic H2 production under simulated sunlight irradiation

Bismuth Vanadate Microspheres: Utilizing Temperature-driven Phase Transition for Improved Sunlight-Driven Photocatalysis and Antibacterial Efficacy

In this work, bismuth vanadate (BiVO4) microspheres are synthesized using a simple, cost effective, co-precipitation technique. This study investigates how the annealing temperature influences the photocatalytic and antimicrobial properties of nanoparticles made of BiVO4. Examining the phase structure, chemical compounds state, composition of chemicals, shape, as well as optical characteristics of the prepared materials, by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Raman analysis, UV-Vis diffuse reflectance spectroscopy (DRS), Photoluminescence (PL) spectroscopy studies. Based on XRD analysis data, BiVO4 exhibits a phase change of the tetragonal structure to monoclinic at 500 °C (BiVO4@500 °C). It is interesting to note that under sunlight irradiation, BiVO4 nanoparticles annealed at 500 °C show excellent photocatalytic behavior in opposition to the dye methylene blue (k = 0.0151 min-1). According to investigations on the development of antibacterial activity through the utilization of BiVO4@500 °C sample by well diffusion method appears to be an effective growth inhibitor of both gram-positive and gram-negative bacteria, such as Bacillus subtilis (B. subtilis), Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Proteus vulgaris (P. vulgaris)), respectively.

Biosynthesis of ZnO NPs and ZnO$$\Vert $$CuO NC using Retama monosperma L. (Boiss) stems extract and their cationic dyes removal from wastewater under direct sunlight irradiation

Biosynthesis of ZnO NPs and ZnO$$\Vert $$CuO NC using Retama monosperma L. (Boiss) stems extract and their cationic dyes removal from wastewater under direct sunlight irradiation

Optimization of Anatase TiO2 Photocatalyst for Diclofenac Degradation by Using Response Surface Methodology

Titanium oxide semiconductors are considered effective photocatalysts for the degradation of organic pollutants. The photocatalytic activity of titanium dioxide is influenced by several factors, one of which is its phase composition, with anatase being considered the phase with the highest photocatalytic activity. In this work, a simple acid-assisted sol–gel process was used to synthesize a pure anatase phase by varying the synthesis and calcination temperature. The synthesized materials were characterized using various techniques and tested under simulated sunlight irradiation for the photocatalytic degradation of the drug diclofenac sodium (DCF), for which the pseudo-first-order apparent degradation rate constant and mineralization efficiency were determined. A pure anatase phase with high photocatalytic activity (up to 97% TOC removal) was obtained when TiO2 was synthesized at between 70 °C and 100 °C and calcined at between 400 °C and 500 °C. Furthermore, the obtained data were used to predict the optimal anatase synthesis and calcination temperatures for DCF removal using a response surface methodology (RSM) method. The model predicted a synthesis temperature of 71 °C and a calcination temperature of 440 °C, which should result in a pseudo-first-order DCF decay rate constant of 0.055 min−1 and a TOC removal rate of 100%. The experimentally determined values for the degradation rate (0.063 min−1) and TOC removal (97%) were in good agreement with the model’s predicted values.

Photocatalysis by Mixed Oxides Containing Niobium, Vanadium, Silica, or Tin

Nb-Sn, V-Sn mixed-metal oxides and Nb-Si, V-Si metal oxide–silicas were successfully synthesized through a “soft” templating method, in which appropriate amounts of metal salts (either niobium(V) chloride, or vanadium(IV) oxide sulfate hydrate or tin(II) chloride dihydrate) or tetraethyl orthosilicate (TEOS) were mixed with hexadecyltrimethylammonium chloride (HDTA) or sodium dodecyl sulfate (SDS) solutions to obtain a new series of mesoporous oxides, followed by calcination at different temperatures. As-obtained samples were characterized by SEM, TEM, XRD, and UV-Vis spectra techniques. The photocatalytic activities of the samples were evaluated by degradation of methyl orange II (MO) under simulated sunlight irradiation. The effects of metal species and calcination temperature on the physicochemical characteristic and photocatalytic activity of the samples were investigated in detail. The results indicated that, compared to pure oxides, mixed-metal oxide showed superior photocatalytic performance for the degradation of MO. A maximum photocatalytic discoloration rate of 97.3% (with MO initial concentration of 0.6·10−4 mol/dm3) was achieved in 300 min with the NbSiOx material, which was much higher than that of Degussa P25 under the same conditions. Additionally, the samples were tested in the photochemical oxidation process, i.e., advanced oxidation processes (AOPs) to treat the commercial non-ionic surfactant: propylene oxide ethylene oxide polymer mono(nonylphenyl) ether (N8P7, PCC Rokita). A maximum of 99.9% photochemical degradation was achieved in 30 min with the NbSiOx material.

Synthesize and characterization of a novel sol–gel-driven Bi2O3 semiconductor: complete degradation and fast photocatalytic activity for paracetamol

Abstract The pollutants are getting released fluently as a waste from the pharmaceutical pollutants leading to the decrease in quality of water. The widespread occurrence of pharmaceutical pollutants poses a serious threat to the environment and human health. Besides, today carbon dioxide emissions and other forms of pollution appear to be a critical global issue. In this study, Bi2O3 catalyst has been prepared via co-precipitation (CP) and a facile sol–gel (SG) methods used as photocatalyst for the degradation of paracetamol (PAR) under different light sources. The preparation method has significant effect on the optical and structural properties of the catalysts. The tetragonal phase of Bi2O3, the presence of more surface OH groups and lower band gap energy remarkably improved the sun-light-driven photoactivity of PAR. The photocatalysts have been characterized by some structural and morphological analysis techniques and optical analysis techniques. In addition, zeta potential (ZP) measurements were performed to explain the impact of the initial pH of solution on photocatalytic degradation. Identification of PAR and the reaction intermediates was determined using Liquid Chromatography-Mass/Mass Spectrometry (LC-MS/MS) technique. Higher photocatalytic activity was obtained with the Bi2O3-SG (1:2) catalyst at pH 5 compared to the activity of Bi2O3-CP. Moreover, Bi2O3-SG (1:2) achieved the highest photocatalytic activity at pH 3. The photocatalytic activity was enhanced, and the time required for 100% degradation of PAR was reduced from 60 min to 30 min and 15 min under UVB irradiation and directly sun light irradiation, respectively. The highest reaction rate (0.086 (min−1)) were obtained in 15 min with the Bi2O3-SG (1:2) catalyst. The results showed TOC removal could be achieved in 60 min 99.19 and 88.97% for Bi2O3-SG and Bi2O3-CP, respectively. In general, sol–gel-driven Bi2O3 as a flower and needle-like morphology, can reveal excellent opportunities in the photocatalytic technology. Graphical Abstract

Silver single atoms and nanoparticles on floatable monolithic photocatalysts for synergistic solar water disinfection

Photocatalytic water disinfection technology is highly promising in off-grid areas due to abundant year-round solar irradiance. However, the practical use of powdered photocatalysts is impeded by limited recovery and inefficient inactivation of stress-resistant bacteria in oligotrophic surface water. Here we prepare a floatable monolithic photocatalyst with ZIF-8-NH2 loaded Ag single atoms and nanoparticles (AgSA+NP/ZIF). Atomically dispersed Ag sites form an Ag−N charge bridge, extending the lifetime of charge carriers and thereby promoting reactive oxygen species (ROS) generation. The photothermal effect of the plasmonic Ag nanoparticles reduces the bacterial resistance to ROS and impairs DNA repair capabilities. Under sunlight irradiation, the synergistic effect of Ag single atoms and nanoparticles enables 4.0 cm2 AgSA+NP/ZIF to achieve over 6.0 log inactivation (99.9999%) for the stress-resistant Escherichia coli (E. coli) in oligotrophic surface water within 30 min. Furthermore, 36 cm2 AgSA+NP/ZIF is capable of disinfecting at least 10.0 L of surface water, which meets the World Health Organization (WHO) recommended daily per capita drinking water allocation (8.0 L). This study presents a decentralized and sustainable approach for water disinfection in off-grid areas.

Utilization of Stable and Efficient High-Entropy (Ni0.2Zn0.2Mg0.2Cu0.2Co0.2)Al2O4 Catalyst with Polyvalent Transition Metals to Boost Peroxymonosulfate Activation toward Pollutant Degradation.

A polyacrylamide gel method has been used to synthesize a variety of polyvalent-transition-metal-doped Ni position of high entropy spinel oxides (Ni0.2Zn0.2Mg0.2Cu0.2Co0.2)Al2O4-800°C (A2) on the basis of NiAl2O4, and the catalytic activity of A2 is studied under the synergistic action of peroxymonosulfate (PMS) activation and simulated sunlight. The A2 containing polyvalent transition metals (Ni2+, Cu2+, and Co2+) can effectively activate PMS and efficiently degrade levofloxacin (LEV) and tetracycline hydrochloride (TCH) under simulated sunlight irradiation. After 90 min of light exposure, the degradation percentages of LEV (50 mg L-1) and TCH (100 mg L-1) degrade by the A2/PMS/vis system reach 87.0% and 90.2%, respectively. The superoxide radicals, photoinduced holes, and singlet oxides dominate the catalytic process, while hydroxyl radicals and sulfate radicals play only a small role. The adsorption energy and charge density difference between different systems and PMS are calculated by density functional theory, and the activation efficiency of PMS is studied by combining with the change of the length of the O─O bond of the PMS after adsorption. The catalytic mechanism of A2/PMS/vis system is proposed, which provides a new idea and method for the study of high entropy oxides in the field of catalysis.

Sun-simulated-driven production of high-purity methanol from carbon dioxide

CO2 conversion to CH3OH under mild conditions is of particular interest yet rather challenging. Both electro- and thermo-catalytic CO2 reduction to CH3OH can only produce CH3OH in low concentration (typically mixed with water), requiring energy-intensive purification processes. Here we design a sun-simulated-driven tandem catalytic system comprising CO2 electroreduction to syngas, and further photothermal conversion into high-purity CH3OH (volume fraction > 97%). We construct a self-supporting electrocatalyst featuring dual active sites of Ni single atoms and encapsulated Co nanoparticles, which could produce syngas with a constant H2:CO ratio of ~2 via solar-powered CO2 electroreduction. The generated syngas is subsequently fed into the photothermal module, which could produce high-purity CH3OH under 1 sun-light irradiation, with a rate of 0.238 gCH3OH gcat–1 h–1. This work demonstrates a feasible and sustainable route for directly converting CO2 into high-purity CH3OH.

Chitosan/Polyvinyl Alcohol/g-C3N4 Nanocomposite Film: An Efficient Visible Light-Responsive Photocatalyst and Antimicrobial Agent

Biopolymer-based nanocomposite film is an efficient material for addressing the increasing levels of pollutants in the environment and also for the production of antimicrobial packing material due to its good film-forming properties, biodegradability, and minimal environmental impact. In particular, chitosan/polyvinyl alcohol/g-C3N4 (CS/PVA/g-C3N4) nanocomposite films with different weight percentages of PVA were prepared using simple methodologies and characterized using XRD, TGA, FT-IR, DSC, FE-SEM, EDX, and elemental mapping analysis. The XRD and FT-IR results validated the nanocomposite film formation. The FE-SEM images showed the smooth surface of the composite films without any wrinkles; the smoothness of the film increased with increases in the PVA loading, and the surface morphologies of the films were largely unchanged. The EDX and elemental mapping analysis validated the presence and uniform dispersion of g-C3N4 within the nanocomposite film. The photocatalytic activity of the CS/PVA/g-C3N4 composite films was assessed by the degradation of rhodamine B dye (RhB) and acetophenone under direct sunlight irradiation. The CS/PVA/g-C3N4 nanocomposite films exhibited superior degradation efficiency toward the RhB dye and acetophenone compared to the bare polymeric film and the g-C3N4 material. The order of degradation for the RhB dye and acetophenone was CS/PVA (1.0) g-C3N4 (95.34%, 33.33%) > CS/PVA (1.5) g-C3N4 (93.18%, 31.31%) > CS/PVA (0.5) g-C3N4 (93.02%, 29.29%) > CS/PVA (90.69%, 26.26%) > g-C3N4 (87.56%, 24%), respectively. Furthermore, the antimicrobial activity of the nanocomposite films was tested against E. coli, Pseudomonas sps., Klesiella sps., and Enterococcus sps., and the CS/PVA (1.5)/g-C3N4 nanocomposite film offered better antimicrobial properties than the other composite films and bare materials. In conclusion, these biopolymer-based nanocomposites are highly efficient and provide a promising path for the development of various biodegradable polymeric nanocomposites for environmental remediation and antibacterial packing applications.

Upcycling Poly(vinyl chloride) and Polystyrene Plastics Using Photothermal Conversion.

Poly(vinyl chloride) (PVC) and polystyrene (PS) are among the least recycled plastics. In this work, we developed a simple and novel strategy to valorize PVC and PS plastics via photothermal conversion to (1-chloroethyl)benzene, a commodity chemical with excellent versatility. As PVC is known to release HCl gas and decompose into conjugated polyenes, we envisioned a dual role for PVC plastics. While the in situ-generated HCl serves as a chlorine source, the resulting dehydrochlorinated-PVC (DHPVC) functions as a photothermal agent to accelerate the hydrochlorination of styrene. We converted PVC and styrene in up to 89% (1-chloroethyl)benzene in less than 1 h of white light irradiation. Subsequent nucleophilic substitution on the chloro-adduct formed 1-phenylethanol (a fragrance additive) and fendiline (a heart disease drug) in high yields. The PVC photothermal hydrochlorination system is applied to various alkenes and is compatible with post-consumer waste PVC plastics and plasticizers. Ultimately, PVC upcycling with photothermally recycled styrene achieved 84% (1-chloroethyl)benzene under white LED light in 1 h, and co-upcycling of PS and PVC achieved 42% yield under focused sunlight irradiation in just 4 min.

Preparation and Characterization of MIL‐53(Al)‐(NH2)@PANI for Tetracycline Removal

ABSTRACTThe growing global demand for water and persistent shortages have underscored the importance of wastewater treatment from industrial and urban sources. Among various approaches, the use of adsorbent materials, particularly metal–organic frameworks (MOFs), has gained significant attention over the past decade due to their exceptional adsorption properties. This study presents a rapid, water‐based synthesis method for MIL‐53(Al)‐(NH2) and its surface modification using polyaniline (PANI). The modified MOFs, MIL‐53(Al)‐(NH2)@PANI, were utilized for the removal and photocatalytic degradation of tetracycline from aqueous solutions. Optimal operational conditions were determined to include an adsorbent dosage of 0.12 g/L, an initial tetracycline concentration of 30 mg/L, a reaction time of 30 min, and a solution pH of 2.5. Kinetic analyses revealed that the adsorption process conforms to the Pseudo‐second‐order kinetic model, with the surface modification by PANI significantly enhancing the adsorption efficiency. The proposed mechanism for photocatalytic degradation involves the generation of reactive radical species, including h+, ˙OH, and ˙O2−, under sunlight irradiation, which synergistically improves the removal efficiency. This study highlights the potential of MIL‐53(Al)‐(NH2)@PANI as an effective adsorbent and photocatalyst for the treatment of antibiotic‐contaminated water, offering a sustainable solution to water pollution challenges.

A Solar-Heated Phase Change Composite Fiber with a Core-Shell Structure for the Recovery of Highly Viscous Crude Oil.

Due to the high viscosity and low fluidity of viscous crude oil, how to effectively recover spilled crude oil is still a major global challenge. Although solar thermal absorbers have made significant progress in accelerating oil recovery, its practical application is largely restricted by the variability of solar radiation intensity, which is influenced by external environmental factors. To address this issue, this study created a new composite fiber that not only possesses solar energy conversion and storage capabilities but also facilitates crude oil removal. PF@PAN@PEG was obtained by coaxial electrospinning processing, with PEG within PAN fibers, and a coating layer was applied to the fiber surface to impart oleophilicity and hydrophobicity. PF@PAN@PEG exhibited a high latent heat value (77.12 J/g), high porosity, and excellent photothermal conversion and oil storage capabilities, significantly reducing the viscosity of crude oil. PF@PAN@PEG can adsorb approximately 11.65 g/g of crude oil under sunlight irradiation. Notably, due to the encapsulation of PEG, PF@PAN@PEG can continuously maintain the crude oil at a phase change temperature by releasing latent heat under specific conditions, effectively reducing its viscosity with no PEG leakage at all. When solar light intensity varied, the crude oil collection efficiency increased by 21.99% compared to when no phase change material was added. This research offers a potential approach for the effective use of clean energy and the collection of viscous crude oil spill pollution.

Synergistic photocatalytic degradation of methylene blue and ibuprofen using Co₃O₄-Decorated hexagonal boron nitride (hBN) composites under Sun-like irradiation.

In this study, we report the synthesis and photocatalytic performance of Co₃O₄-decorated hexagonal boron nitride (hBN) composites for degrading methylene blue (MB) and ibuprofen (IBF) under sunlight irradiation. Using a dry impregnation method, the composites were prepared with varying Co₃O₄ loadings (0.5%, 1%, 2%). Comprehensive characterization confirmed the successful incorporation and uniform distribution of Co₃O₄ on the hBN matrix. Photocatalytic experiments revealed that 1% Co₃O₄-hBN composite exhibited the highest activity, achieving nearly 100% MB degradation in 60min and 90% IBF degradation in 120min. The enhanced photocatalytic efficiency is attributed to the synergistic effects between Co₃O₄ and hBN, which extend light absorption and promote charge separation. Our findings demonstrate the potential of Co3O₄-decorated hBN composites as effective photocatalysts for environmental remediation. The study provides a foundation for further exploration of these materials, including their long-term stability and application to a broader range of pollutants.

Green synthesis of ZnO nanoparticles using Justicia adhatoda for photocatalytic degradation of malachite green and reduction of 4-nitrophenol.

Achieving the smallest crystallite/particle size of zinc oxide nanoparticles (ZnO NPs) reported to date, measuring 5.2/12.41 nm with Justicia adhatoda (J. adhatoda) leaf extract, this study introduces a facile green synthesis. Utilizing aqueous J. adhatoda leaf extract as both a reducing and stabilizing agent, the method leverages the plant's rich phytochemical composition to produce highly crystalline and morphologically controlled ZnO NPs. This precise particle size control highlights the effectiveness of the synthesis process in morphological tuning. The synthesized NPs were thoroughly characterized using XRD, UV-vis spectroscopy, FTIR, FESEM, and HRTEM, which collectively revealed superior crystallinity, controlled morphology, and unique surface properties conferred by phytochemical bio-capping. The photocatalytic performance of these biogenic ZnO NPs was evaluated for the degradation of two model pollutants: malachite green (MG), a synthetic dye, and 4-nitrophenol (4-NP), a toxic organic compound. The NPs exhibited exceptional photocatalytic efficiency, achieving 99.8% MG degradation within 180 minutes and demonstrating a rapid photocatalytic reduction of 4-NP to 4-aminophenol with a reaction rate constant of 0.245 min-1 under UV and sunlight irradiation. Mechanistic studies attributed this high performance to reactive oxygen species (ROS) generation and electron-hole pair interactions, supported by improved charge separation and high surface area. This work not only establishes the potential of J. adhatoda-mediated ZnO NPs in addressing persistent organic pollutants but also sets a benchmark for size-controlled NPs synthesis. By delivering scalable and eco-friendly water remediation technologies, this study advances green nanotechnology.

Superior photocatalytic activity of Mn vanadate/reduced graphene oxide magnetic nanocomposite for the oxidation of methylene blue dye under sunlight irradiation

Superior photocatalytic activity of Mn vanadate/reduced graphene oxide magnetic nanocomposite for the oxidation of methylene blue dye under sunlight irradiation