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Multifunctional and Recyclable TiO2 Hybrid Sponges for Efficient Sorption, Detection, and Photocatalytic Decomposition of Organic Pollutants
摘要： Developing techniques for monitoring and removing organic pollutants such as solvents and dyes in environmental media is a very important task nowadays. To get rid of the pollutants, efficient materials that can sorb, detect, and decompose such compounds have been consistently sought after. Herein, we demonstrate a simple and inexpensive method to fabricate eco-friendly multifunctional and recyclable TiO2 hybrid sponges composed of a polydimethylsiloxane (PDMS) network and functional nanoparticles. Water-soluble crystals were used to construct porous templates and TiO2 nanoparticles were additionally integrated into the templates where liquid PDMS was filled. After curing the PDMS, the TiO2 integrated hybrid sponges were finally obtained by dissolving the templates with water. By using the fabricated hybrid sponges, sorbed organic pollutants were qualitatively detected via molecular-specific Raman signals. Furthermore, we showed the recyclability by achieving photocatalytic decomposition of the sorbed pollutants induced by the TiO2 nanoparticles. These results are instructive for further applications and also contribute toward solving problems relating to environmental pollution.
关键词： TiO2 hybrid sponge,Raman detection,photocatalytic decomposition,organic pollutants,efficient sorption
更新于2025-11-25 10:30:42
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Mesoporous TiO2-BiOBr Microspheres with Tailorable Adsorption Capacities for Photodegradation of Organic Water Pollutants: Probing Adsorption-Photocatalysis Synergy by Combining Experiments and Kinetic Modeling
摘要： Understanding adsorption-photocatalysis synergy helps advance solar-driven photodegradation of organic wastewater pollutants. To evaluate the synergy, mesoporous TiO2(amorphous)-BiOBr microspheres were facilely synthesized as model photocatalysts and characterized by XRD, SEM, TEM/HRTEM, XPS, nitrogen adsorption-desorption, UV-vis DRS, photoluminescence, and FTIR. The characterizations and photodegradation tests suggested that the composites had both adsorption sites and photocatalysis sites on BiOBr phase, while homogeneously distributed TiO2 in BiOBr microplates tailored the size of BiOBr crystallites. Accordingly, surface areas of the composites spanned from 22 to 155 m2/g and adsorption capacities for methyl orange (MO) ranged from 16 to 54 mg/g, controlled by the TiO2 content. In addition to experiments, kinetic modeling that combined adsorption with photocatalysis was developed and aided elucidating the synergy and quantitatively evaluating the composites with extracted rate constants from experimental data. The rate constant of the composite (Ti/Bi = 0.6) was calculated to be 3 times that of the pure BiOBr. Though adsorption promoted MO photodegradation, the capacity of the composite for MO adsorption and photodegradation decreased dramatically during the cycling tests. Nevertheless, this problem did not happen during photodegradation of rhodamine B and phenol on the composite and photodegradation of MO on pure BiOBr. This was explained by possible accumulation of degradation intermediates on the composite surface. This study provides a useful approach to investigate the adsorption-photocatalysis synergy from the perspectives of experiments and kinetic modeling and implies the necessity of scrutinizing the adverse effects of high levels of adsorption on recyclability of the photocatalysts.
关键词： Organic pollutants photodegradation,Kinetic modeling,TiO2-BiOBr microspheres,Tailorable adsorption capacities,Adsorption-photocatalysis synergy
更新于2025-11-14 17:03:37
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2D visible-light-driven TiO2@Ti3C2/g-C3N4 ternary heterostructure for high photocatalytic activity
摘要： A novel 2D visible-light-driven TiO2@Ti3C2/g-C3N4 ternary heterojunction photocatalyst with modified interfacial microstructure and electronic properties was synthesized by ultrasonic-assisted calcination method. The remarkably active g-C3N4 could provide high productivity of photogenerated electrons and holes. Meanwhile, the O/OH-terminated Ti3C2 and by-product TiO2 could act as excellent supporters by migrating electrons in TiO2@Ti3C2/g-C3N4 hybrids. As a result, the highest photocatalytic activities in the degradation of aniline and RhB were increased to 5 and 1.33 times higher than that of pristine g-C3N4 under visible-light irradiation, respectively. Furthermore, we proposed that n–n heterojunction and n-type Schottky heterojunction were built up across their interfaces, which efficiently improve the transition of electrons and further promote the photocatalytic activity of TiO2@Ti3C2/g-C3N4 hybrids. More appealingly, all the results highlight that the environment-friendly TiO2@Ti3C2/g-C3N4 heterojunction hybrids would be desirable candidates for pollutants degradation.
关键词： 2D materials,photocatalytic activity,TiO2@Ti3C2/g-C3N4,ternary heterojunction,pollutants degradation,visible-light-driven
更新于2025-11-14 17:03:37
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Plasmonic MoO2 nanospheres assembled on graphene oxide for highly sensitive SERS detection of organic pollutants
摘要： The molybdenum oxide and graphene oxide (MoO2/GO) nanocomposite has been fabricated via simple hydrothermal assisted synthesis using Mo and MoO3 as precursors. The MoO2 nanospheres with porous hollow structure are assembled onto GO nanosheets. Profiting from the plasmonic effects of MoO2 and synergistic effect of MoO2 and GO, this hybrid nanomaterial exhibits significantly enhanced surface enhanced Raman scattering (SERS) activity for organic pollutants. The detection limit for rhodamine 6G (R6G) is 1.0 × 10?9 M, and the maximum enhancement factor (EF) reaches up to 1.05 × 107, which is the best among the semiconductor-based SERS materials. For practical application, the MoO2/GO SERS substrates are also applied to detect Methylene blue (MB) in river water, and the detection limit (1.0 × 10?8 M) can be acquired. Pyrene is also chosen as probe molecule, and quantitative determination is achieved with detection limit of 1.0 × 10?7 M. These demonstrate the well feasibility for multi-molecule detection. Furthermore, the nanocomposite displays high stability, reproducible stability, and acid and alkali resistance.
关键词： Organic pollutants,Plasmonic effect,SERS,Graphene oxide,Detection,MoO2
更新于2025-11-14 15:27:09
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The role of the reactive oxygen species and the influence of KBiO3 synthesis method in the photodegradation of methylene blue and ciprofloxacin
摘要： KBiO3 was synthesized by three methods: chemical substitution, hydrothermal and sonochemical. All reaction products were analyzed by X-ray powder diffraction and reveal that KBiO3 presents a cubic structure. The morphology of each sample was analyzed with scanning electron microscopy (SEM), and the micrographs show particles with cube-like (chemical substitution), spheres-like (sonochemical) and flakes-like (hydrothermal) shape. HR-TEM technique was used to confirm the crystal structure and to determine the particle size of the samples, also it was used to corroborate the morphology. The photocatalytic activity of KBiO3 was evaluated on the reactions of the degradation of methylene blue (MB) and Ciprofloxacin (CPFX). An almost 100% discoloration of MB was reached at 120 min with KBiO3 obtained by the sonochemical method and a 67% degradation of CPFX was obtained by KBiO3 synthesized by the hydrothermal method. These results were associated with the catalyst morphology and organic adsorption on the surface of the catalyst. With the aim for a further understanding of the photocatalytic degradation of MB and CPFX, scavengers such as benzoquinone, isopropanol, and catalase were added to the photocatalytic reaction in order to identify the reactive oxygen species (ROS) involved. It has been found that hydrogen peroxide (H2O2) was the primary oxidizing species for the degradation of MB; meanwhile in the case of the oxidation of CPFX occurred by the presence of the superoxide radical (O2?·).
关键词： Photocatalysis,Organic pollutants,Reactive oxygen species,Scavengers,KBiO3
更新于2025-09-23 15:23:52
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Photocatalytic Degradation of Bisphenol A Induced by Dense Nanocavities Inside Aligned 2D-TiO2 Nanostructures
摘要： The preparation of materials with aligned porosity in the nanometer range is of technological importance for a wide range of applications in molecular filtration, biomaterials and catalysis. Herein we present the advantages offered by cryo – lyophilisation technique as a smart and green non-standard concept to produce dense regular polyhedral nanocavities inside the 2D TiO2 nanosheets. Hierarchical morphologies of nanocavities start to appear at temperature higher than 800 °C and are strongly influenced by polymorph TiO2 evolution competing reactions. The small angle X-ray scattering (SAXS) analysis confirms self-assembled 3D nanocavities with size range from 5 to 10 nm in both length and width, and depth ~ 3.6 nm formed after realising of the confined ice-water. It was found that nanocavities enhance significantly the absorption properties of TiO2 in the UV region, thereby providing a new approach to increase the photoreactivity of 2D TiO2 nanosheets. The annealed precursors containing aqueous solution of peroxo polytitanic acid (PPTA) at 800 °C exhibited the highest photoactivity in degrading bisphenol A (BPA) due to evenly distributed nanocavities inside single anatase TiO2 nanocrystals interconnected and aligned onto the 2D TiO2 nanosheet arrays.
关键词： emerging pollutants,nanoconfined water,photocatalysis,nanocavities,freeze-drying,anatase TiO2
更新于2025-09-23 15:23:52
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Interfacial engineering of Fe2O3@BOC heterojunction for efficient detoxification of toxic metal and dye under visible light illumination
摘要： Recent developments of small band gap semiconductor coupled bismuth carbonate (BOC) heterojunction are advantageous for photocatalysis application because of their improved solar harvesting ability and enhanced charge-carrier collection. In this work, we have developed iron (III) oxide decorated bismuth carbonate (Fe2O3@BOC) heterojunction via a simple two-step process. The developed heterojunction exhibits excellent photocatalytic activity towards reduction of carcinogenic and mutagenic Cr(VI) to nontoxic Cr(III) and degradation of toxic dye [methylene blue (MB)] under visible light illumination. Further investigation revealed that the loading of Fe2O3 nanoparticles had an impact on efficient charge carrier collection at the interface of Fe2O3@BOC heterojunctions. The unprecedented photocatalytic activity for Fe2O3@BOC1 heterojunction at room temperature could be attributed due to the enhancement in light absorption ability and suppression of electron–hole pair recombination at the heterojunction interface. In addition, reduction in efficacy of the heterojunction with increase in loading of Fe2O3 nanoparticles on BOC surface further confirms the role of interface on the modulation of photocatalytic activity. The role of photogenerated electrons and reactive oxygen species involved during photocatalytic reduction of Cr(VI) and degradation of MB was studied in detail. Moreover, recyclability experiment demonstrates that the developed photocatalyst can be reused without decay in performance. Finally, development of inexpensive prototype reactor is demonstrated towards reduction of Cr(VI) and degradation of MB under continuous flow operation. Thus, good efficacy of the developed reactor for cleaning of toxic pollutants in water makes the heterojunction (Fe2O3@BOC1) a promising photocatalyst for water purification in near future.
关键词： photocatalytic activity,charge separation,Heterojunction,toxic pollutants,visible light
更新于2025-09-23 15:23:52
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A magnetic and carbon dot based molecularly imprinted composite for fluorometric detection of 2,4,6-trinitrophenol
摘要： A magnetic molecularly imprinted composite was prepared by reverse microemulsion using carbon dots (CDs), Fe3O4 as the co-nucleus, and a molecularly imprinted polymer (MIP; with 2,4,6-trinitrophenol as the template) acting as recognition sites. The composite of type CD/Fe3O4@MIPs was characterized by transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), zeta potentiometric analysis, X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). The results showed that the composite MIP has a spherical shape with average diameter of 200 nm. They also showed that the composite contains core-shell structures with several Fe3O4 nanoparticles and CDs embedded in each of the microsphere. The composite can extract 2,4,6-trinitrophenol (TNP) and has an imprinting factor of 3.6. It has high selectivity and sensitivity for TNP which acts as a quencher of the fluorescence of the CDs (with excitation/emission maxima at 370/470 nm). The limit of detection of this fluorometric TNP assay is 0.5 nM. The method was successfully applied to the determination of TNP in spiked tap water and river water samples, and recoveries ranged from 89.4% to 108.5% (with an RSD of <6%).
关键词： Fluorescence quenching,Fe3O4 nanoparticles,Stern-Volmer plot,Environmental pollutants,Reverse microemulsion method,Selective recognition,Molecularly imprinting
更新于2025-09-23 15:23:52
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Fabrication of electrochemically nonporous NiO–ZnO/TiO2 nanotubes/Ti plates for photocatalytic disinfection of microbiological pollutants
摘要： Nonporous NiO–ZnO/TiO2 nanotubes/Ti photocatalyst plates were fabricated via facile electrochemical method. The structural and morphological properties of the modified plates were investigated by scanning electron microscopy and X-ray diffraction, while their photoelectrochemical (PEC) characterizations were evaluated by transient photocurrent responses and electrochemical impedance spectroscopy. Antimicrobial activities of the fabricated plates against Escherichia coli bacteria and Candida albicans fungi were studied under UV light irradiation. The results indicated that the photocatalytic and PEC activities of the NiO–ZnO/TiO2 nanotubes/Ti plates are much higher than those of TiO2 nanotubes/Ti, ZnO/TiO2 nanotubes/Ti and NiO/TiO2 nanotubes/Ti. The synergetic effect among NiO, ZnO and TiO2 nanotubes motivated a fast charge separation as well as a slow electron/hole recombination, thus increasing the photocatalytic performance of the nonporous NiO–ZnO/TiO2 nanotubes/Ti photocatalyst plate.
关键词： Microbiological pollutants,Heterogeneous catalysis,Photocatalytic disinfection,NiO–ZnO hybrids
更新于2025-09-23 15:23:52
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Magnetite-Supported Gold Nanostars for the Uptake and SERS Detection of Tetracycline
摘要： Magnetite nanoparticles (MNPs) decorated with gold nanostars (AuNSs) have been prepared by using a seed growth method without the addition of surfactants or colloidal stabilizers. The hybrid nanomaterials were investigated as adsorbents for the uptake of tetracycline (TC) from aqueous solutions and subsequent detection using surface-enhanced Raman scattering (SERS). Several parameters were investigated in order to optimize the performance of these hybrid platforms on the uptake and SERS detection of TC, including variable pH values and the effect of contact time on the removal of TC. The spatial distribution of TC and AuNS on the hybrid composites was accomplished by coupling SERS analysis with Raman imaging studies, allowing also for the determination of the detection limit for TC when dissolved in ultrapure water (10 nM) and in more complex aqueous matrices (1 μM). Attempts were also made to investigate the adsorption modes of the TC molecules at the surface of the metal NPs by taking into account the enhancement of the Raman bands in these different matrices.
关键词： SERS,antibiotics,magnetite nanoparticles,Au nanostars,water pollutants
更新于2025-09-23 15:23:52