The integration of green-synthesized nanomaterials with environmental processes offers promising strategies for mitigating anthropogenic contaminants in ecosystems. In this study, TiO2 nanoparticles were synthesized using aqueous extracts from four herbal plants: Curcuma longa, Ocimum basilicum, Plencranthus amboinicus, and Calotropis procera, representing an eco-friendly approach to nanomaterial fabrication. Comprehensive characterization using SEM, TEM, XRD, UV-Vis spectroscopy, FTIR spectroscopy, UV-DRS, and PL was employed to elucidate the morphology, crystallinity, and electronic properties of the nanoparticles. Microscopy-based analyses revealed distinct plant-mediated morphologies that strongly influenced photocatalytic performance in the degradation of Brilliant Green (BG) dye under sun-light irradiation, with Curcuma longa-derived TiO2 exhibiting the highest degradation efficiency. This work demonstrates how green synthesis, combined with advanced characterization, provides mechanistic insights into nano-geochemical interactions between nanoparticles and contaminants. The findings highlight the potential of plant-mediated TiO2 nanoparticles as sustainable photocatalysts for dye remediation and offer a model for designing eco-friendly nanomaterials to address broader environmental challenges.

Abstract An optimized Iron spinel ferrite (Fe 3 O 4 ) synthesis for the highest catalytic activity by the ultrasonic-assisted reverse co-precipitation (US-RP) method was tested, substituting the divalent cation (Me 2+ ) source from Fe 2+ for Zn 2+ , Ni 2+ or Co 2+ . The respective ZnFe 2 O 4 , NiFe 2 O 4 or CoFe 2 O 4 spinel ferrite nanoparticles were successfully synthesized in this work. The use of this US-RP method employing the ion source MeCl 2 (Me 2+ = Zn 2+ , Ni 2+ or Co 2+ ) yields a magnetic biphasic monocrystalline composite MeFe 2 O 4 /α-Fe 2 O 3 nanomaterial with potential photocatalytic properties. The amount of ferrite in the biphasic composite differed for each ion source, being 25.6%, 34.2%, and 38.2% for the CoFe 2 O 4 < NiFe 2 O 4 < ZnFe 2 O 4 , respectively. With an inverse trend in the magnetic properties, CoFe 2 O 4 > NiFe 2 O 4 > ZnFe 2 O 4 , with a magnetic saturation ( M s ) of 42.5, 28.4, and 2.7 emu g −1 . These magnetic properties were attributed to the differences in the degree of inversion ( δ ) calculated from Raman spectroscopy and Rietveld refinements. As for the photocatalytic potential for nitrobenzene (NB) degradation, the half-life calculated under the tested conditions was in the range of 72 – 113 min, following a reaction mechanism that yields H2O, CO 2 and 4-nitrophenol (4-NPh) as an intermediate product (< 5.65%). Showing an optimal efficiency at a pH = 2 when using the sample containing CoFe 2 O 4 . Graphical Abstract

Synozol Navy Blue poses severe ecological risks, necessitating advanced treatment approaches. Ni-Ag co-doped ZnO (Ni-Ag@ZnO) catalyst was synthesized via the sol-gel method and characterized using XRD, SEM-EDX, BET, UV-Vis, PL, and XPS. In contrast to previous research primarily focused on simple model dyes, this study demonstrates the effective degradation of Synozol Navy Blue, a highly resistant azo dye, utilizing Ni-Ag co-doped ZnO under visible light. Comprehensive characterization, including XPS analysis, offered valuable insights into the oxidation states and successful incorporation of Ni and Ag. Furthermore, scavenger studies, mineralization tests, and pH-dependent performance evaluations elucidated the mechanistic pathways and conditions that optimize photocatalytic activity. Ni-Ag doping reduced crystallite size from 35.4 to 29nm and increased surface area from 1.89 to 2.54m²/g, while narrowing the band gap from 3.42 to 3.28eV. Photoluminescence confirmed reduced electron-hole recombination. Under optimized conditions of 75mg/L dye concentration, 0.03g/50 mL catalyst dosage, pH 2-, and 50-min contact time 10% Ni-Ag@ZnO doping ratio achieved 81% degradation efficiency under solar light irradiation, significantly outperforming pure ZnO. The process followed pseudo-first-order kinetics (k = 2 × 10⁻² min⁻¹) and attained 80% mineralization (TOC removal) in 60min. Scavenging tests identified hydroxyl and superoxide radicals as the dominant reactive species, with IPA and BQ enhancing charge separation. These results establish 10% Ni-Ag@ZnO as a promising eco-friendly photocatalyst for wastewater remediation.

The simultaneous removal and detection of mixed water pollutants-particularly synthetic dyes and antibiotics-remains a major challenge for environmental remediation technologies. Herein, a ligand-engineered cadmium-based metal-organic framework (Cd-MOF), synthesized from bis(2-carboxyethyl) isocyanurate (H2Cei) and 1,4-bis(1H-imidazol-1-yl)methyl]benzene (Bimb) ligands, that exhibits dual functionality for visible-light-driven photocatalytic degradation and fluorescent sensing is reported. The Cd-MOF demonstrates high crystallinity, mesoporosity (BET surface area: 598m2g-1), and structural robustness. Under visible light, it achieves >96% degradation of Rhodamine B (RhB), Methylene Blue (MB), and ciprofloxacin (CPF) within 150min, and maintains efficient performance in a ternary mixture, with selectivity toward RhB. Radical trapping and photophysical studies reveal a reactive oxygen species-driven degradation mechanism, while DFT calculations confirm pollutant-induced band gap modulation and enhanced charge transfer. Moreover, the Cd-MOF selectively detects CPF via fluorescence quenching with a detection limit of 0.563ppm, showing excellent sensitivity, reusability, and pH stability. This study presents a structurally tunable and multifunctional MOF platform for integrated pollutant degradation and real-time antibiotic sensing, supported by combined experimental and theoretical validation.

This study examines the synergy of carbon fibers (CFs) and an infiltrated TiO2 nanocrystalline layer for photocatalytic degradation of methylene blue (MB). The CFs@TiO2 nanocomposite was developed using Vapour Phase Infiltration (VPI) of TiO2 into polyacrylonitrile fibers with 5-160 infiltration cycles and subsequently carbonized at 900 °C. This integrated production method enables precise integration of TiO2 and consistent coating over the fiber surface. SEM confirms the TiO2 layer thickening from 15.7 ± 2.4 nm to 34.7 ± 3.4 nm as the cycles increase from 40 to 160, while EDX and EDXRF indicate a similar rise in TiO2 content. XRD and Raman spectroscopy confirm the production of anatase TiO2 for VPI 40 c and higher, attributed to size-induced crystallization. UV-Vis DRS demonstrates that the optical bandgap varies with the cycle number in accordance with the development of the TiO2 layer. The outcomes of photocatalytic experiments under UV illumination indicate that the maximum degradation rate is achieved with the thickest coating. The CFs@TiO2 demonstrate exceptional cycle stability. This study emphasizes the potential of VPI-derived CFs@TiO2 as durable and effective photocatalysts.

ABSTRACT Multilayer dielectric coatings consisting of alternating titanium dioxide (TiO₂) and silicon dioxide (SiO₂) layers were fabricated on glass substrates using a sol–gel spin-coating technique to evaluate their optical and environmental functionality. The objective was to develop a low-cost, sustainable thin-film system exhibiting high reflectivity and effective photocatalytic activity. Five TiO₂/SiO₂ bilayers were synthesised using titanium isopropoxide and tetraethyl orthosilicate precursors. X-ray diffraction confirmed the amorphous structure, while FTIR spectra verified Ti–O–Ti, Si–O–Si, and Ti–O–Si bonding, indicating strong interlayer interactions. UV–Vis–NIR analyses showed a prominent reflection band with a peak reflectance of 99.4% at 800 nm due to constructive interference within the multilayer stack. FESEM images revealed uniform, defect-free coatings with sharp interfaces. Photocatalytic degradation of methylene blue under sunlight demonstrated significant dye removal, highlighting the photocatalytic efficiency of TiO₂ layers. Overall, the reproducible TiO₂/SiO₂ multilayers show strong potential for photonic and wastewater-treatment applications.

Abstract The breakdown of pollutants, specifically dyes, using natural light sources, presents a significant area of investigation in fundamental material science. This study demonstrates the successful degradation of dyes through the utilisation of nanomaterials made from earth-abundant and non-toxic elements, specifically copper, zinc, tin, and sulfur (CZTS). The research concentrated on identifying the optimal pH levels for sol-gel and solvothermal synthesis methods to ensure appropriate phase formation of CZTS nanomaterials. Utilising the primary characterisation, X-ray diffraction, the tetragonal crystal structure of the nanomaterial was confirmed. The Raman analysis complemented the XRD findings to establish the phase purity of the material. The X-ray photoelectron spectroscopy investigation revealed that Cu, Zn, and Sn exhibited oxidation states of +1, +2, and +4, respectively. Additionally, the compositional verification was achieved through XPS and EDS analysis. At a lower pH level, agglomerated morphology and improper growth were observed, whereas at a higher pH level, nearly seven, proper growth accompanied by reduced agglomeration was evident. The black colour of the nanomaterial reflects that absorption takes place within the visible range of the spectrum, as verified by a UV-Vis spectrophotometer. The measured band gap was approximately 1.5 eV, rendering it suitable for the photocatalytic degradation of dyes in visible light conditions. Upon exposure to visible light with CZTS functioning as a catalyst, the rate constants (k) observed for the degradation of rhodamine-B and methylene blue, which are two target pollutants, were measured at 0.0172 min-1 and 0.0229 min-1, respectively. The assessment of the dyes' recyclability significantly boosts their applicability in environmental restoration efforts.

This study focuses on the successful production and detailed characterization of surfactant-aided bismuth vanadate (BiVO4) nanoparticles (NPs), designed specifically to enhance their use in environmental remediation. The BiVO4 NPs were synthesized using a simple co-precipitation method, followed by the addition of a surfactant before the final calcination step. The researchers proposed that this surfactant-assisted approach would allow for precise control over the particle size, morphology, and surface area, which, in turn, would significantly boost the material's catalytic action. The resulting BiVO4 NPs were thoroughly analyzed using various techniques, including X-ray diffraction (XRD), Fourier transform infra-red microscopy (FTIR), Energy dispersive X-ray microscopy (EDX), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectroscopy (DRS). These tests confirmed the formation of crystalline BiVO4 NPs with highly desirable structural and optical properties, particularly strong visible-light absorption. The prepared BiVO4 NPs demonstrated exceptional efficiency in the photocatalytic degradation of organic contaminants (such as selected dyes or pharmaceuticals) when exposed to visible light. The rate of degradation was markedly superior to that achieved by BiVO4 synthesized without the surfactant. This enhanced performance is attributed to the resulting better charge separation and an increased number of available active sites on the nanoparticle surface. Furthermore, the surfactant-functionalized BiVO4 NPs also exhibited excellent antibacterial activity against both Gram-negative and Gram-positive bacterial strains, thereby establishing the material as a truly multi-functional agent. The combined, improved performance in both photocatalysis and antibacterial activity positions these surfactant-assisted BiVO4 NPs as a promising, cost-effective, and highly active nanomaterial for advanced applications in wastewater treatment and the preservation of public health.

The modification of titanium dioxide (TiO 2 ) with zirconium dioxide (ZrO 2 ) supported by chitosan (CS) was carried out to obtain a binary oxide system, which should have the properties of both components such as high stability, solar propulsion, non-toxicity and good corrosion resistance. The sample with a ratio of 1:1:3 (TiO 2 :CS:ZrO 2 ) showed the best results with a photocatalytic degradability of 99 % after 90 minutes at a pH of 7 and in 10 ppm Malachite Green (MG). Under visible light, the photocatalytic degradability of the CS/TiO 2 -ZrO 2 hybrid was more than 90 %. The enhanced photocatalytic degradation of MG by hybrid catalyst beads was attributed to the synergistic effect of hybrid CS/TiO 2 -ZrO 2 .

Application of synthesized recyclable magnetic nanocomposite MnFe12O19/BiOI in photocatalytic degradation of ciprofloxacin in presence of simulated sunlight

Effect of manganese doping on the activity of NiFe2O4 for the photocatalytic degradation of methylene blue

As human society continues to develop and progress, the hazards posed to human health by emerging pollutants are becoming increasingly serious due to their unique characteristics such as specific toxicity, persistence, and bioaccumulation. It is critical to develop highly sensitive, renewable nonmetallic surface-enhanced Raman scattering (SERS) platforms for environmental monitoring, particularly for the trace detection of mercury ions in water. Here, we utilized a band-tunable F4TCNQ/MoS2 heterojunction achieving an ultrasensitive limit of detection (LOD) of 2.77 × 10-11 M for Hg2+ in pure water. The enhancement factor (EF) for the 989 cm-1 peak was found to be approximately 4.2 × 105, while that for the 722 cm-1 peak was 2.8 × 105. Such sensitivity arises due to the interfacial charge transfer (CT) and the weak electromagnetic interaction between the heterojunction and Hg2+ with the Raman reporter molecule 4-methylpyridine (4-MPy). The substrate exhibits remarkable selectivity against interfering ions (Ca2+, Mg2+, Pb2+, etc.,), along with high reproducibility (RSD < 9.33%), and stability up to one month under environmental conditions. The results indicate that the detection sensitivity is comparable to or even better than that achieved with the conventional SERS substrate to enable specific detection of Hg2+. Moreover, the substrate can be reused through photocatalytic degradation showing a 30 min duration for complete removal of Hg2+, enabled by the F4TCNQ/MoS2 heterostructure. This offers significant advantages for detecting Hg2+ in complex environmental samples, such as seawater and soil leachate, while also proving valuable for environmental monitoring and food safety applications.

Sustainable production of CH4, an industrially important gas, from renewable resources presents a critical solution to energy security challenges. This study demonstrates photocatalytic conversion of glucose, a model biomass compound, to CH4 using a metal co-catalyst loaded TiO2 photocatalyst under ambient conditions. We confirmed that CH4 was formed through photocatalytic reduction of CO2, which was generated in situ during glucose oxidation, establishing a closed-loop conversion of biomass-derived carbon within a single reaction system. PtOx-TiO2 (x = 0, 1) exhibited significantly higher activity for CH4 production than PdOx-TiO2 (x = 0, 1). The CH4 yield with PtOx loading was approximately ten times greater than that obtained with PdOx loading, with an optimal PtOx loading of 2.0 wt% yielding the highest CH4 amount of 10.600 µmol L- 1 after 6h. In contrast, PdOx-TiO2 showed a higher selectivity for H2 generation. Analysis of the reaction products, including sugars (arabinose, erythrose, and glyceraldehyde) and organic acids (formic acid, acetic acid, and gluconic acid), elucidated the glucose degradation pathways. The mechanism of CH4 formation was identified as the methanation of CO2 and H+, both produced during photocatalytic oxidation of glucose and water. Deuterium-labeling experiments further revealed that the hydrogen atoms in CH4 originated from both glucose decomposition and water splitting. These findings demonstrate a novel and sustainable tandem photocatalytic process that integrates oxidation and reduction reactions on a single catalyst surface, providing mechanistic and practical insights into the direct conversion of biomass into CH4 under mild conditions.

Herein, a visible light-active, facile, ternary magnetic MCNFs/GO nanocatalyst comprising enzyme-extracted-cellulose nanofibers, graphene oxide, and iron oxide nanoparticles for effective degradation of malachite green (MG) dye is reported. The nanocatalyst was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, vibrating sample magnetometry, Brunauer-Emmett-Teller analysis, and UV-diffuse reflectance spectroscopy. The nanocatalyst exhibited an average diameter of 19.93 ± 0.94 nm, a high surface area of 212.39 m2 g-1, paramagnetic properties, and a band gap energy of 1.8 eV. The nanocatalyst was successfully demonstrated to photodegrade MG dye from the aqueous solution with a maximum 99.01% removal percentage at a nanocatalyst dose of 122.93 mg, MG dye concentration of 11.06 mg/L, pH = 6.37, irradiation time of 32 min, and constant agitation at room temperature using the central composite design approach of response surface methodology. The equilibrium data were best characterized by the Langmuir isotherm model, and the pseudo-second-order kinetic model was found to describe the degradation kinetics. Liquid chromatography-mass spectrometry analysis confirmed complete mineralization of dye, with the degradation pathways identified. The nanocatalyst also demonstrated high MG dye degradation in real wastewater samples, with more than 96% recyclability during seven consecutive degradation cycles, indicating its stability and reusability. The augmented photodegradation efficiency of the MCNFs/GO nanocatalyst may be attributed to synergistic interactions of three components, resulting in a highly efficient photocatalyst for real-world wastewater treatment.

The sustainable fabrication of multifunctional nanocomposites remains a major challenge in environmental nanotechnology. In this study, a selenium-doped Au/ZnO/Fe₃O₄ nanocomposite (GW@Se-AZF) was successfully synthesized through a green-mediated route using Geranium wallichianum extract, which acted simultaneously as a reducing and stabilising agent. Structural and functional characterization confirmed the multiphase composition and nanoscale features of the product. UV-Vis analysis revealed a surface Plasmon resonance peak corresponding to Au incorporation, while FTIR spectra indicated phytochemical capping groups and metal-oxygen vibrations. XRD confirmed crystalline phases of ZnO, Fe₃O₄, Au, and Se with an average crystallite size of ~ 22nm. SEM images demonstrated quasi-spherical, uniformly distributed nanoparticles (NPs), and EDX confirmed the elemental presence of Zn, Fe, Au, Se, and O. Functionally, the GW@Se-AZF nanocomposite exhibited dual performance. It showed highly selective and sensitive colorimetric detection of Hg²⁺ ions with a detection limit of 92.7 nM, attributable to synergistic interactions between Se doping and Au NPs. GW@Se-AZF demonstrated efficient photocatalytic activity under sunlight, achieving rapid degradation of organic dyes including methylene blue (≈ 91%), methyl orange (≈ 89%), and methyl violet (≈ 90%) within 60min. This work demonstrates a sustainable strategy for developing multifunctional nanocomposites with integrated sensing, photocatalytic, and magnetic properties, offering significant potential for water purification and heavy metal monitoring in real environmental systems.

Sustainable and reusable nanofiber mats embedded with green-synthesized selenium nanoparticles for photocatalytic degradation of cationic and reactive dyes

Nanostructured titanium dioxide (TiO 2 ) was synthesized via a hydrothermal method to enhance photocatalytic degradation of organic and pharmaceutical contaminants in wastewater. Characterization techniques confirmed the formation of anatase-phase TiO 2 with a tetragonal structure, spherical morphology, and an average crystallite size of 29 nm. The material exhibited a band gap of 3.1 eV. The TiO 2 solution has proven to be very effective in accelerating the breakdown of pharmaceutical and organic contaminants in wastewater, as evidenced by several methods, including high-performance liquid chromatography (HPLC) and Gas chromatography (GC). Photocatalytic performance was evaluated under varying catalyst concentrations and pH levels. Optimal degradation efficiency (72%) was achieved at pH 10, demonstrating TiO 2 's potential as an effective photocatalyst for wastewater treatment.

Machine learning-Powered estimation of simultaneous removal of sulfamethoxazole, 17-β Estradiol, and carbamazepine via photocatalytic degradation with M-Al@ZnO.

The strategic fabrication of efficient, renewable, and sustainable visible photon-responsive advanced heterogeneous photocatalysts is currently relevant for decontaminating pharmaceutical pollutants. Here, we report the fabrication of a unique Cu3P-ZnWO4 (CZ) heterojunction nanocomposite (NC) uniformly decorated onto a porous poly(EGDMA) monolith (PEM) template, which features a remarkable surface area, excellent structural integrity, and high porosity. Varying ratios of Cu3P to that of ZnWO4 reveal a sequence of Z-scheme heterostructured NCs, i.e., CZ-5, CZ-10, CZ-15, CZ-20, and CZ-25. The structurally engineered translucent PEM template and the CZ NCs decorated PEM are characterized by p-XRD, FT-IR, FE-SEM-EDAX, HR-TEM-SAED, VB-XPS, BET/BJH, UV-Vis-DRS, and PL analysis to confirm the formation of the desired photocatalyst with impressive structural and surface morphological features. The photocatalytic degradation efficiency shows that the CZ-20 NC-dispersed PEM (CZ-20@PEM) photocatalyst proffers robust photocatalytic performance for decontaminating moxifloxacin residues. Moreover, to determine the optimal conditions for fast and efficient photocatalysis, the influence of various analytical parameters, including solution pH (2-9), photocatalyst dosage (10-150mg), pollutant concentration (10-50ppm), oxidizers (KBrO3 & H2O2), and light intensities (150-300W/m2) has been comprehensively studied. The CZ-20@PEM photocatalyst exhibits ≥ 99.4% moxifloxacin dissipation in ≤ 20min, using 240W/m2 visible light intensity. Based on VB-XPS analysis and trapping experiments, a feasible photocatalytic mechanism was proposed to clarify the reactive species predominantly participating in the photocatalytic process. This work demonstrates an efficient and sustainable approach for removing moxifloxacin drug residues, underscoring the potential of nanocomposite-encapsulated polymer monoliths as a next-generation photocatalytic platform for future water treatment applications.

Herein, the synthesis of an indium-doped cerium oxide/graphitic carbon nitride (In–CeO2/g-C3N4) S-scheme heterojunction aimed at optimizing photocatalytic degradation under visible light for the remediation of pharmaceutical wastewater is reported. The materials were synthesized via a hydrothermal process, in which pure CeO2 and In-modified CeO2 (In–CeO2) were initially synthesized, followed by the incorporation of g-C3N4 to produce the heterojunction. A series of characterization methods, such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), validated the effective synthesis and structural integrity of CeO2, In–CeO2, and In–CeO2/g-C3N4. The optical bandgap of the samples was determined, presenting a reduction from 2.97 eV for CeO2 to 2.69 eV for In–CeO2/g-C3N4, which facilitated better visible-light absorption. Photocurrent and electrochemical impedance spectroscopy (EIS) characterizations indicated enhanced charge separation and reduced recombination in the In–CeO2/g-C3N4 heterojunction. Photocatalytic experiments for the degradation of levofloxacin (LVX) demonstrated that the In–CeO2/g-C3N4 heterojunction achieved 85% degradation, significantly higher than those achieved by In–CeO2 (63%) and CeO2 (44%), highlighting the enhanced photocatalytic performance of the heterojunction. The higher photocatalytic activity is attributed to the formation of an S-scheme charge migration channel, enabling efficient charge separation. Results indicate that the In–CeO2/g-C3N4 heterojunction has great potential for water purification applications, particularly in degrading drug contaminants.