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Heterogeneous Growth of Continuous ZIF-8 Films on Low-Temperature Amorphous Silicon
摘要： Thin amorphous silicon films, deposited at low temperature by Inductively Coupled Plasma Chemical Vapor Deposition, have, for the first time, been employed as substrate for ZIF-8 growth. In order to investigate the role of the surface chemistry on the nucleation process, films have also been grown on other silicon-based substrates such as H-terminated Si(100), SiO2 and quartz. Film preparation was carried out at room temperature using a mixed Zn nitrate and imidazole solution in methanol or ethanol. Using methanol, continuous ZIF-8 films were obtained on amorphous Si and H-terminated Si(100), while less homogeneous films were formed on the other surfaces. In ethanol, slower growth rates occurred and thinner films, compared to the ones in methanol, were obtained. These slower rates highlight the different effects of the four surfaces on the growth process. These differences have been related to the silanol density of the surfaces and to the Lewis basic strength which affect imidazole moiety deprotonation. H-terminated Si(100) and amorphous Si turned out to be the most reactive surfaces, whereas on quartz and, especially, on SiO2 reactivity was much lower. Experimental results have been validated by the DFT modelling of the proton exchange, which takes place between the imidazole group and the surface. Finally, the VOCs adsorption capability of ZIF-8 films grown on amorphous silicon has been evaluated through temperature desorption experiments.
关键词： a-Si layer,ZIF-8 coating,growth mechanisms,VOCs adsorption,surface chemistry
更新于2025-11-21 11:03:25
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The coherence between TiO2 nanoparticles and microfibrillated cellulose in thin film for enhanced dispersal and photodegradation of dye
摘要： Microfibrillated cellulose (MFC) was used to enhance the dispersal and photocatalytic properties of TiO2 nanoparticles. With the small amount of MFC (0.1 wt.% or 0.3 wt.%), TEM images showed that particle agglomeration was greatly minimized due to the coherence between TiO2 nanoparticles and MFC. The surface area and pore volume of TiO2 nanoparticles was enhanced as proven in N2 adsorption-desorption analysis. Thermogravimetric and Fourier transform infrared spectra further confirmed the presence of MFC in TiO2/MFC coating solution. Using commercial adhesive, TiO2 and TiO2/MFC were spray coated on polyvinyl chloride sheet. The photocatalytic thin films were examined using scanning electron microscope with Energy dispersive X-ray analysis. The presence of MFC was not only helpful to enhance particle dispersal but also supportive to increase the hydrophilicity of the thin film. In comparison to TiO2 coating, the films were capable to adsorb 50% more methylene blue in 90 min. TiO2/MFC coatings removed 90% of methylene blue dye in 90 min under UV irradiation.
关键词： Spray coating,Photocatalysis,Dye,TiO2 nanoparticles,Microfibrillated cellulose,Adsorption
更新于2025-11-19 16:56:35
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Adsorption and Photocatalytic Decomposition of Gaseous 2-Propanol Using TiO2-Coated Porous Glass Fiber Cloth
摘要： Combinations of TiO2 photocatalysts and various adsorbents have been extensively investigated for eliminating volatile organic compounds (VOCs) at low concentrations. Herein, TiO2 and porous glass cloth composites were prepared by acid leaching and subsequent TiO2 dip-coating of the electrically applied glass (E-glass) cloth, and its adsorption and photocatalytic ability were investigated. Acid leaching increased the specific surface area of the E-glass cloth from 1 to 430 m2/g while maintaining sufficient mechanical strength for supporting TiO2. Further, the specific surface area remained large (290 m2/g) after TiO2 coating. In the photocatalytic decomposition of gaseous 2-propanol, the TiO2-coated porous glass cloth exhibited higher adsorption and photocatalytic decomposition ability than those exhibited by the TiO2-coated, non-porous glass cloth. The porous composite limited desorption of acetone, which is a decomposition intermediate of 2-propanol, until 2-propanol was completely decomposed to CO2. The CO2 generation rate was affected by the temperature condition (15 or 35 °C) and the water content (2 or 18 mg/L); the latter also influenced 2-propanol adsorption in photocatalytic decomposition. Both the conditions may change the diffusion and adsorption behavior of 2-propanol in the porous composite. As demonstrated by its high adsorption and photocatalytic ability, the composite (TiO2 and porous glass cloth) effectively eliminates VOCs, while decreasing the emission of harmful intermediates.
关键词： air purification,composite,adsorption,microporous material,porous glass,photocatalyst,TiO2
更新于2025-11-19 16:51:07
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A high-performance room temperature methanol gas sensor based on alpha-iron oxide/polyaniline/PbS quantum dots nanofilm
摘要： A high-performance room temperature methanol gas sensor based on alpha-iron oxide/polyaniline/lead sulfide quantum dots (α-Fe2O3/PANI/PbS QDs) nanofilm was demonstrated in this paper, among which the α-Fe2O3 was an urchin-shaped hollow microsphere. The sensing film was fabricated on an epoxy substrate with interdigital electrodes via successive ionic layer adsorption and reaction technique. The prepared α-Fe2O3/PANI/PbS QDs nanocomposite was examined by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, scanning election microscopy and Fourier transform infrared spectrum. The methanol sensing performances of the α-Fe2O3/PANI/PbS QDs film sensor were investigated against methanol from 10 to 100 ppm at room temperature. The experimental results indicated that the methanol sensor in this work had an excellent response, outstanding selectivity and good repeatability at room temperature. The underlying sensing mechanism of the α-Fe2O3/PANI/PbS QDs film toward methanol was ascribed to a series of interactions and changes on the surface of thin films, which make their resistance change greatly. Larger surface area and much more active adsorption sites also played an important role.
关键词： Methanol gas sensor,Room temperature,Successive ionic layer adsorption and reaction,Hydrothermal method,α-Fe2O3/PANI/PbS QDs
更新于2025-11-14 17:15:25
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Enhanced removal and detection of benzo[a]pyrene in environmental water samples using carbon dots-modified magnetic nanocomposites
摘要： Magnetic nanoparticles (MNPs) have already proven their e?cacy in the disposal of a wide array of environmental contaminants in recent years. However, the di?culties in dispersibility and agglomeration of MNPs arising from its own physical and chemical properties limit its large-scale application. Herein, we fabricated the carbon dots/fatty acid-coated MNPs (CDs/C11-Fe3O4) through a facile and simple method. To utilize the advantage of carbon dots, these limitations can be mitigated by diminishing the size of MNPs and modifying the surface of MNPs. Detailed characterization including VSM, FT-IR, XPS and TEM conformed that the higher adsorption capacity of CDs/C11-Fe3O4 is mainly attributed to low average size (< 8 nm), which is obviously lower than that of C11-Fe3O4 (about 13 nm). The CDs/C11-Fe3O4 showed higher adsorption performance than that of C11-Fe3O4 nanocomposites (76.23 ng mg?1 for CDs/C11-Fe3O4 and 59.89 ng mg?1 for C11-Fe3O4). The adsorption processes of BaP on both C11-Fe3O4 and CDs/C11-Fe3O4 nanocomposites are exothermic, and well simulated by pseudo-second-order model. Moreover, the CDs/C11-Fe3O4 were also applied for the detection of BaP in large-volume water samples, which satis?es the China environmental protection standard, are promising candidates for water remediation.
关键词： Magnetic nanocomposites,Carbon dots,Hydrophilicity,Adsorption,Benzo[a]pyrene
更新于2025-11-14 17:15:25
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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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Synergistic effects and kinetics of rGO-modified TiO2 nanocomposite on adsorption and photocatalytic degradation of humic acid
摘要： Graphene oxide was prepared using the modified Hummers method and reduced graphene oxide (rGO) - titanium dioxide (TiO2) nanocomposite was synthesised using the one-step hydrothermal treatment. The synergistic effects on adsorption and photocatalytic properties of the rGO-TiO2 nanocomposite for the humic acid removal were systematically investigated. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman and infrared (IR) spectroscopy indicate that GO was partially reduced to reduced graphene oxide (rGO) in the hydrothermal synthesis process and anatase TiO2 nanoparticles uniformly grew on the surface of rGO. The photoelectron and photohole generated under visible light irradiation were effectively separated on the surface of rGO-TiO2. The rGO-TiO2 nanocomposite exhibited higher photocatalytic activity as a result of the synergistic effects of surface functional groups for adsorption and the excellent conductivity for photocatalytic reaction. The effect of rGO-TiO2 nanocomposite dosage, light intensity and system temperature on the removal of humic acid solution was investigated. The results show that the removal efficiency of humic acid increased with system temperature and light intensity. When the dosage of rGO-TiO2 nanocomposite was 1.2 g/L, the temperature, the light intensity and the pH of this system was 303 K, 4.37 Wm?2 and 7, respectively, the removal efficiency of humic acid reached 88.7% under visible light irradiation.
关键词： Synergistic effects,rGO,Humic acid,TiO2,Adsorption and photocatalysis
更新于2025-11-14 17:03:37
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Interesting makeover of strontium hexaferrites for environment remediation from excellent photocatalysts to outstanding adsorbents via inclusion of Mn3+ into the lattice
摘要： Manganese incorporated strontium hexaferrites with composition SrMnxFe12-xO19 (x= 0.0, 0.4, 0.8, 1.2, 1.6, 2.0, 3.0, 4.0 and 5.0) were fabricated via chemical co-precipitation methodology. Various characterization techniques were employed to investigate the physical properties of the synthesized hexaferrites. Powder X-Ray Diffraction (XRD) patterns revealed the formation of hexagonal phase with P63/mmc space group. FE-SEM micrographs exhibited hexagonal morphology of the synthesized materials; particle size of 125-150 nm range was observed. EDX spectra unveiled the presence of desired elements. The lattice interplanar fringe width from HR-TEM images was observed to be 0.22 nm, 0.26 nm and 0.27 nm indexed to (114), (107) and (203) planes of the manganese doped strontium hexaferrite. Surface area of the synthesized hexaferrites was found to be in the range of ~7.8 to ~8.4 m2/g, scrutinized by Brunauer–Emmet–Teller (BET) plots. Saturation magnetisation values were found to decrease with increase in Mn content from 38.7 to 11.7 emu/g, albeit retaining sufficient magnetic strength to be recovered using an external magnet. Absorption edge for all the hexaferrites was found to lie in the visible region of the spectrum. The oxidation state of different elements present in synthesized hexaferrites was scrutinized using X- ray Photoelectron Spectroscopy (XPS). To explore the catalytic efficiency of the synthesized hexaferrites, photo-fenton degradation of methyl orange (MO), remazol deep red (RDR) and p-nitrophenol (PNP) was employed. All the synthesized hexaferrites were found to be highly proficient, degrading the pollutants upto ~98%. Interestingly, astonishing adsorption of ~92.7 % was showcased by SrMn5Fe7O19, prior to the addition of oxidizing agent indicating the symptomatic transformation from excellent photocatalyst to outstanding adsorbents via incorporation of Mn3+ into the lattice. The maximum adsorption capacity of 56.20 and 112.35 mg/g was observed for MO and RDR, respectively.
关键词： photo-fenton degradation,strontium hexaferrites,adsorption,chemical co-precipitation method,manganese substituted ferrites
更新于2025-11-14 17:03:37
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Efficient removal of cationic dyes from water by a combined adsorption-photocatalysis process using platinum-doped titanate nanomaterials
摘要： In this study, two types of titanate nanomaterials (TNMs) including titanate nanosheets (TNS) and titanate nanotubes (TNT) were hydrothermally prepared by controlling reaction times, and then the platinum (Pt)-doped TNMs were fabricated. The photocatalytic performance of as-prepared materials was compared with that of the commercially available TiO2 P25. It was revealed that changing the morphology of TiO2 particles could enhance their adsorption ability and photocatalytic activity for the removal of cationic dyes from water. In particular, all prepared materials displayed greater removal of methylene blue than of P25 through the synergy of adsorption and photocatalysis; however, such an effect was not so pronounced for anionic dyes. For cationic dyes (methylene blue and rhodamine B) and anionic dyes (methyl orange and naphthol blue–black), TNT presented higher photocatalytic activity than TNS. The TNMs, after Pt doping, significantly enhanced photocatalytic activity compared to the pristine ones. Remarkably, 0.5% by weight Pt-doped TNS achieved 100% removal of methylene blue and rhodamine B after 120 min and 140 min of UV irradiation, respectively, outperforming P25, although Pt-doped TNMs showed lower photocatalytic performance than P25 for anionic dyes.
关键词： Photocatalysis,Cationic dyes,Titanate nanomaterials,Adsorption,Platinum doping
更新于2025-11-14 15:13:28
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Structures and electronic properties of Cu <i> <sub/>m</sub></i> Co <i> <sub/>n</sub></i> O <sub/>2</sub> ( <i>m</i> ? <i>+</i> ? <i>n</i> ?=?2–7) clusters
摘要： A theoretical study was carried out of CumConO2(2 ≤ m + n ≤ 7) clusters using density functional method. O2 molecules are adsorbed at top sites. After adsorption, O2 molecules are activated. The Δ2E value of CuCo3O2 cluster is obviously the smallest, indicating that its thermodynamic stability is the worst. While Cu6CoO2 displays stronger chemical stability. Charge transfer from Cu–Co to anti-bonding orbital of O2, which leads to O–O getting longer. The Mulliken charge population and PDOS analysis are also discussed.
关键词： electronic properties,O2 adsorption,density functional theory,structures and stability
更新于2025-09-23 15:23:52