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oe1(光电查) - 科学论文

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出版时间
  • 2019
研究主题
  • Dye-sensitized solar cell
  • Hierarchical structure
  • Light scattering
  • TiO2 photoanode
应用领域
  • Nanomaterials and Technology
机构单位
  • National Sun Yat-sen University
  • Wenzao Ursuline University of Languages
793 条数据
?? 中文（中国） ▾

  • Enhanced photocatalytic carbon dioxide reforming of methane to fuels over nickel and montmorillonite supported TiO2 nanocomposite using monolith photoreactor

    摘要： Conversion of carbon dioxide (CO2) and methane (CH4) to fuels using photo-technology is a cleaner pathway compared to thermal reforming, since its uses only light irradiations, while producing valuable chemicals. In this study, structured nickel (Ni) and montmorillonite (MMT) supported TiO2 composite, synthesized by a sol-gel method, was tested for photocatalytic reduction of CO2 using fixed-bed and monolith photoreactors. The performance of structured nanocatalyst was evaluated using CO2-H2 system via photocatalytic reverse water gas shift (RWGS) reaction and CO2-CH4 system via photocatalytic dry reforming of methane (DRM). Using photocatalytic RWGS, CO was detected as the main products, while the performance of Ni-MMT/TiO2 composite was expressively higher than using MMT/TiO2 and TiO2 catalysts. This was obviously due to larger surface area by MMT dispersion and hindered charges recombination rate by Ni. Similarly, using DRM, H2 and CO were the main products, while their selectivity was greatly dependent on the initial CH4/CO2 molar feed ratios. At a lower CH4/CO2 ratio, more CO was produced, while a higher feed ratio promoted H2 production. This shows, composite catalyst was more favorable for CO2 adsorption, while CH4 was competitively adsorbed during photo-catalysis process. Comparatively, Ni-MMT/TiO2 catalyst reveals higher photo-activity and selectivity in a monolith photoreactor than using fixed-bed reactor under the same operating conditions. This enhanced photoactivity was due to higher photonic flux with enlarged active surface area due to monolithic support and efficient sorption process. The stability of Ni/TiO2 dispersed MMT for CO and H2 production via DRM process sustained in cyclic runs using monolithic support. Hence, using Ni/MMT modified TiO2 catalyst and monolith photoreactor, CO2 and CH4 can efficiently be converted to renewable fuels under light irradiations and would be a great benefit to the environment.

    关键词： Photo-technology,Ni/TiO2,Dry reforming of CH4,Monolith photoreactor,Montmorillonite,CO2 reduction

    更新于2025-09-04 15:30:14

  • WS2 nanodots-modified TiO2 nanotubes to enhance visible-light photocatalytic activity

    摘要： WS2 nanodots-modified TiO2 nanotubes (TNT/WND) composites were fabricated via one-pot hydrothermal method for the first time. The physical and photophysical properties of the as-prepared photocatalysts were characterized by XRD, TEM, HRTEM, BET, UV-vis, and PL. The results demonstrated that WS2 nanodots have been successfully anchored on the inner wall of TiO2 nanotubes. TNT/WND composites showed excellent photocatalytic activity toward photodegradation of rhodamine B (RhB) under visible-light, which mainly attributed to the synergistic effect from relative low recombination rate of the photogenerated electron-hole pairs and high specific surface area.

    关键词： Semiconductors,Photocatalysis,WS2 nanodots,Structural,TiO2 nanotubes,Nanocomposites

    更新于2025-09-04 15:30:14

  • Tetrathiafulvalene Scaffolds Based Sensitizer on Hierarchical Porous TiO <sub/>2</sub> : Efficient Light Harvesting Material for Hydrogen Production

    摘要： In this work, a photochemical device that contains thioalkyl substituted tetrathiafulvalene dyes and hierarchical porous TiO2, has been designed and successfully employed in visible light-driven hydrogen production. The design strategy boost up the desirable photophysical properties of the catalysts and well supported from the optical, electrochemical and computational studies. The introduction of thioalkyl substituted tetrathiafulvalene dyes as light harvesting sensitizers onto the porous TiO2 triggers unprecedented high rate of hydrogen evolution. This study focuses on the role of thiafulvalene scaffold which can promote ultrafast interfacial electron injection from excited state dye into the hierarchical porous TiO2 conduction band. The purposeful construction of this integrated composite G3T3 (dye content 1.0 μmol in 10 mg Pt-TiO2 composite) significantly increases the hydrogen production rate of 24560 μmol.h-1g-1 cat with high apparent quantum yield (AQY) ~ 41%. In the study, both sensitizers absorption onset extends up to 500 nm in solution and 600 nm on hierarchical porous TiO2. Density functional theory (DFT) in the present study described that the HOMO levels are delocalized on anthracene as well as tetrathiafulvalene donor units, and LUMO covers on to the carboxylate anchoring group in both dyes. This study unveiled first time that a tetrathiafulvalene scaffolds in porous TiO2 attributes to positive synergistic effects in hydrogen production.

    关键词： Tetrathiafulvalene,Hydrogen Production,Photocatalysis,Hierarchical Porous TiO2,Visible Light

    更新于2025-09-04 15:30:14

  • Refluxed Esterification of Fullerenes Conjugated P25 TiO2 Promotes Free Radical Scavenging Capacity and Facilitates Anti-aging Potentials in Human Cells

    摘要： Titanium dioxide nanomaterials have good capability to prevent human cells from damage under UV irradiation. However, some studies indicated that the nanoscale of titanium dioxide could potentially cause harmful effects such as free radicals generation under UV irradiation and thereby accelerate the progress of cell aging. Fullerenes can scavenge large amounts of free radicals due to the fact that fullerenes contain enormous amount of π electrons with low lying lowest unoccupied molecular orbital (LUMO), but its adverse properties, such as the poor solubility in water, restricted the applicability. In this study, we employed water-soluble carboxylic acid fullerenes (C60-COOH and C70-COOH) as the free radical scavenger and modify onto the surface of titanium dioxide by refluxed esterification (P25/C60-COOH or C70-COOH) technique. The conformation and properties of theses nanomaterials were characterized by techniques and equipments such as X-ray diffraction (XRD), energy dispersive spectroscopy analysis (EDS), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), high-resolution transmission electron microscopy (HRTEM), and Fourier transform infrared spectroscopy (FT-IR). We also introduced methylene blue (MB) and rhodamine B (Rh B) as indicator to evaluate and demonstrate the scavenging capacity of these nanomaterials. Moreover, we examined the biocompatibility and UV protection capacity of our P25/fullerene composites in human 293T cells, and applied luciferase activity assay to investigate the possible underlying cell protection mechanisms exhibited by these nanomaterials. Our data indicate that both P25/C60-COOH and P25/C70-COOH could protect human cells against UV exposure. P25/C70-COOH exhibits great anti-inflammation capacity, while as P25/C60-COOH exhibits great anti-oxidative stress and anti-DNA damage capacity. Our results suggest that most of our P25/fullerenes composite materials have the ability to reduce free radicals and exhibit high biomedical potential in anti-inflammation, anti-oxidant, and anti-aging applications.

    关键词： refluxed esterification,anti-oxidative stress,UV protection,TiO2/fullerene composites,anti-inflammation

    更新于2025-09-04 15:30:14

  • Pressure-Induced Phase Transitions in TiO <sub/>2</sub> Rutile Nanorods

    摘要： TiO2 nanorods (diameter of 6-8 nm) with the rutile-type structure have been investigated by Raman spectroscopy under high pressure. Additional bands in the Raman spectrum at ambient pressure are interpreted as resulting from defects that break the Raman selection rules as the simulated vibrational density of states (vDOS) is in good agreement with the experimental spectrum. Under pressure, the rutile structure transforms to the baddeleyite one at P~16 GPa. After pressure cycle, the α-PbO2 phase is recovered. The sequence of phase is discussed in terms of thermodynamics and kinetics based on crystallographic relationships. Contrary to other 1D TiO2 nanomaterials that adopt a metastable structure, the nanorods studied in this work show little impact of the morphology on the phase transitions sequence compared to the bulk TiO2.

    关键词： phase transitions,vibrational density of states,TiO2 nanorods,high pressure,Raman spectroscopy

    更新于2025-09-04 15:30:14

  • Visible light thiocyanation of <i>N</i> -bearing aromatic and heteroaromatic compounds using Ag/TiO <sub/>2</sub> nanotube photocatalyst

    摘要： In this study, Ag/TiO2 nanotubes (Ag/TNT) were synthesized via simple hydrothermal process, and this photocatalyst was successfully exploited in thiocyanation reactions at room temperature under visible light irradiation. Four classes of important heterocyclic compounds including indole, aniline, pyrrole and 2-amino thiazole derivatives via Ag/TNT treated with ammonium thiocyanate formed the corresponding thiocyano compounds in moderate to excellent yields. Plasmonic property and catalytic performance of Ag nanoparticles (which mainly deposited on the surface of TNT) in absorbing species containing sulfur atoms were key components for the reactions to proceed. This potent, simple and versatile protocol reported for the first time afforded thiocyanation reactions of aniline, pyrrole and 2-amino thiazole derivatives under visible light. The reactions proceeded through a radical pathway by applying air molecular oxygen as a low-cost and environmentally friendly terminal oxidant.

    关键词： thiocyanation,photocatalyst,visible light,heterocyclic compounds,Ag/TiO2 nanotubes

    更新于2025-09-04 15:30:14

  • Degradation kinetics and mechanism of 3-Chlorobenzoic acid in anoxic water environment using graphene/TiO <sub/>2</sub> as photocatalyst

    摘要： Degradation kinetics and mechanism of 3-Chlorobenzoic acid(3-CBA) in anoxic water environment using graphene/TiO2 (GR/TiO2) as photocatalyst had been investigated. The effects of various parameters such as catalyst dosage, pH, initial concentration, catalyst reuse and dissolved oxygen(DO) on 3-CBA photocatalytic degradation kinetics were studied. The qualitative and quantitative analysis for degradation intermediate products and parent compound were studied by using HPLC, HPLC/MS/MS and IC technologies. The results show that the residual concentration of 3-CBA has a good linear relationship and its correlation coefficient R2are all greater than 0.985 by Langmuir-Hinshelwood (L-H) dynamic model under different photocatalytic degradation conditions; Some oxidative degradation products such as 3-chlorophenol, resorcinol, hydroxyquinol are generated, and some reductive degradation products such as 3-chlorobenzaldehyde, 3-hydroxybenzaldehyde, 3-hydroxybenzyl alcohol, cyclohexanediol are produced, and part of 3-CBA are mineralized to generate CO2 when DO is in the range of 0.5~1.0 mg/L; When DO is less than 0.28 mg/L, photocatalytic reduction mainly occurs. The results provide a theoretical basis for photocatalytic in-situ remediation of pollutants in anoxic water environment.

    关键词： Degradation kinetics,Degradation mechanism,3-Chlorobenzoic acid,GR/TiO2,Anoxic water environment

    更新于2025-09-04 15:30:14

  • Cu-Doped TiO2: Visible Light Assisted Photocatalytic Antimicrobial Activity

    摘要： Surface contamination by microbes is a major public health concern. A damp environment is one of potential sources for microbe proliferation. Smart photocatalytic coatings on building surfaces using semiconductors like titania (TiO2) can effectively curb this growing threat. Metal-doped titania in anatase phase has been proven as a promising candidate for energy and environmental applications. In this present work, the antimicrobial efficacy of copper (Cu)-doped TiO2 (Cu-TiO2) was evaluated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) under visible light irradiation. Doping of a minute fraction of Cu (0.5 mol %) in TiO2 was carried out via sol-gel technique. Cu-TiO2 further calcined at various temperatures (in the range of 500–700 ?C) to evaluate the thermal stability of TiO2 anatase phase. The physico-chemical properties of the samples were characterized through X-ray diffraction (XRD), Raman spectroscopy, X-ray photo-electron spectroscopy (XPS) and UV–visible spectroscopy techniques. XRD results revealed that the anatase phase of TiO2 was maintained well, up to 650 ?C, by the Cu dopant. UV–vis results suggested that the visible light absorption property of Cu-TiO2 was enhanced and the band gap is reduced to 2.8 eV. Density functional theory (DFT) studies emphasize the introduction of Cu+ and Cu2+ ions by replacing Ti4+ ions in the TiO2 lattice, creating oxygen vacancies. These further promoted the photocatalytic efficiency. A significantly high bacterial inactivation (99.9999%) was attained in 30 min of visible light irradiation by Cu-TiO2.

    关键词： Staphylococcus aureus,phase transition,antibacterial coatings,photocatalysis,doping,Cu-doped TiO2,Escherichia coli

    更新于2025-09-04 15:30:14

  • [IEEE 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - Kuala Lumpur (2018.8.15-2018.8.17)] 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - Detecting Hydrogen Using TiO<inf>2</inf>-B<inf>2</inf>O<inf>3</inf> at Different Operating Temperature

    摘要： Performance of TiO2-B2O3 gas sensor that annealed using nitrogen at 650°C for 30 minutes was observed and analyzed. The sensing film of the gas sensor was prepared by mixing TiO2-B2O3 with an organic binder. The sensing film was characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The gas sensor was exposed to hydrogen at a concentration of 100 - 1000 ppm with operating temperatures of 100°C and 200°C. However, no response was detected for 100 ppm at 100°C. But, as the operating temperature was increased to 200°C, the gas sensor indicated a good response for 100 ppm of hydrogen. The gas sensor exhibited p-type response based on decreased current when exposed to hydrogen. The sensitivity of gas sensor was calculated at 1.00, 2.18 and 3.58 for 100 ppm, 500 ppm and 1000 ppm respectively, at an operating temperature of 200°C.

    关键词： TiO2-B2O3,hydrogen,organic binder,nitrogen,gas sensor

    更新于2025-09-04 15:30:14

  • Synthesis and Characterization of Tio2/C Composite for Photocatalytic Degradation of Dyes.

    摘要： Titanium dioxide TiO2 nanoparticles have moderate catalytic activity due to its wide band-gap and high rate of electron-hole recombination [1]. The TiO2 electrical conductivity poor is improved by mixing with other materials. Therefore, TiO2 based nanocomposites have been synthesized to increase the photocatalytic activity, as well as their structural characteristics and electrochemical performance, using dopants like carbon, nitrogen, sulfur and others. TiO2/C composite has been proven to be a promising photocatalyst for pollutants, due to C-doping, morphology, structure and mixed phases [1]. Carbon precursors are reported to synthesize TiO2/C, such as: glucose, oleic acid, carbon nanofiber, graphene oxide, activated carbon, carbon nanotubes, graphite, resorcinol and formaldehyde. Dyes used for industries, are significant sources of environmental pollution, because they are non-biodegradable [2]. Methyl orange (MO) and methyl blue (MB) have been used to help determine the activity of the photocatalyst [3]. The reagents used were: anatase powder 99.8% (metals basis), sucrose (99.5%), H2SO4 (65% wt), distilled water, MO (MW=327.33g/mol) and MB (MW=319.85g/mol). TiO2/C composites were synthesized via infiltrating sucrose into anatase. In a typical synthesis, anatase (A) and sucrose (S) with molar ratio of A/S=6, sulfuric acid and distilled water were mixed completely. The mixture was then put in a drying oven, treated at 100°C for 6h and subsequently at 160°C for 6h. The resulting brown precursor powder was carbonized in a tubular furnace at 800°C for 1h in argon atmosphere. Rigaku D-Max 2200 difractometer was used to obtain XRD patterns using Cu Kα radiation. The surface morphology and the crystalline phases were examined with Field Emission Transmission Electron Microscope, JEM 2010F JEOL. The photocatalytic activity was tested for degradation of MB and MO with an initial concentration of 20 ppm, using 0 and 0.34 g/L of TiO2/C, under radiant flux provided by 175 W UV. The MB and MO concentrations were measured by UV–vis spectroscopy (Aiglet-Vis spectrophotometer). The XRD patterns of TiO2/C composite is shown in Fig. 2, in which all the characteristic diffraction peaks of the TiO2/C composite can be respectively indexed with planes of anatase phase of TiO2 (JCPDS No. 21-1272). Moreover, a small peak at 11.5° is observed, characteristic of weakly ordered graphitic microstructure, indicating the trace amount of graphite in the composite [4]. No significant peaks of carbon or rutile are observed after the precursor powders are heat treated under argon atmosphere, which suggesting its amorphous nature and confirmed the high purity of the TiO2/C composite [5], because impurities have been reported due to the transformation from anatase to rutile phase [1]. The broad diffraction peaks indicate the sample’s nanocrystalline nature. Fig. 3a shows the micrographs of TEM bright field of powders; it is clearly seen that the TiO2/C composite powders have mostly spherical morphology. Further, it can be estimated that the particle size of samples is of the microscale order with grain size of the range of 20-30nm. Fig. 3b shows the atomic structure and the crystallinity of TiO2/C composite through HRTEM. The insert image shown in Figure 3b give the corresponding Fast Fourier Transform (FFT) pattern of the anatase; this pattern displays (101) and (200) planes from the interplanar spacing of 0.352 and 0.189 nm respectively (JCPDS No. 21-1272). The results of XRD concurred with the electron diffraction pattern created by FFT from HRTEM. The degradation percentage for MO and MB were 99.95 and 99.99 % at 15 min on TiO2/C whereas 86 and 81 % at 90 min for MB and MO in the absence of catalyst is illustrated in Fig. 5. TiO2/C composite was synthetized using anatase and sucrose by obtaining a precursor powder at low temperature (160°C), which is carbonized at 800°C in argon atmosphere. The XRD analysis reveals that the TiO2/C composite is a phase anatase unique structure with high crystallization, which had no impurities, but it showed a trace amount of graphite in the composite. The TiO2/C composite were found to be efficient catalyst for the photodegradation of MB and MO dyes under UV irradiation. The reaction was found to follow pseudo-first order kinetics described it well. This method could be extended to synthesize a variety of other composites for photocatalytic degradation of dyes.

    关键词： anatase,TiO2/C composite,dyes,photocatalytic degradation,sucrose

    更新于2025-09-04 15:30:14