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Effective synthesis of nanoscale anatase TiO <sub/>2</sub> single crystals using activated carbon template to enhance the photodegradation of crystal violet
摘要： Nanoscale anatase TiO2 single crystals were successfully synthesized using three kinds of activated carbon (AC) templates through a simple sol–gel method. The optimal photocatalyst (T‐WOAC) was obtained using wood‐based AC template. X‐ray diffraction, transmission electron microscopy and Brunauer–Emmett–Teller analyses revealed that T‐WOAC possessed a small crystallite size of 8.7 nm and a clear mesoporous structure. The photocatalytic properties of samples were then evaluated through photodegradation of crystal violet (CV). Results implied that the photocatalysts prepared using the AC templates exhibited superior photocatalytic activity to that of the original TiO2. This enhancement may be due to the small crystallite size, large specific surface area and pore volume of the catalysts prepared with ACs. T‐WOAC showed high photocatalytic activity, CV degradation of 99.01% after 120 min of irradiation and k = 0.03914 min?1, which is 3.9 times higher than that of the original TiO2 (k = 0.00994 min?1). This result can be mainly attributed to the application of WOAC with moderate specific surface area and pore volume to produce T‐WOAC. Alkaline conditions benefitted the photodegradation of CV over photocatalysts. This work proposes a possible degradation mechanism of CV and indicates that the fabricated photocatalysts can be used to effectively remove CV from aqueous solutions.
关键词： photocatalyst,anatase TiO2 single crystals,sol–gel,crystal violet,activated carbon
更新于2025-11-14 17:04:02
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Oxygen-Deficient Dumbbell-Shaped Anatase TiO2-x Mesocrystals with Nearly 100% Exposed {101} Facets: Facile Synthesis, Growth Mechanism, and Enhanced Photocatalytic Performance
摘要： Developing hierarchical TiO2 superstructures with novel morphologies and intriguing photoelectric properties for utilizing solar energy is known to be an effective approach to alleviate the serious problems of environmental pollution. Herein, unique oxygen-deficient dumbbell-shaped anatase TiO2-x mesocrystals enclosed by ~100% {101} facets were readily synthesized via mesoscale transformation in the TiCl3-acetic acid mixed solution, followed by calcination under vacuum. These mesocrystals exhibited much higher photoreactivity toward removing the model pollutants of methyl orange and CrVI than tetragonal bipyramid anatase nanocrystals, anatase truncated mesocrystals built from truncated tetragonal bipyramid anatase nanocrystals, and anatase mesocrystals constructed by ~100% {101} facets exposed anatase nanocrystals, revealing that both the oxidation and reduction abilities of anatase TiO2 were simultaneously enhanced upon fabricating oxygen-deficient mesocrystalline architeture with ~100% exposed {101} facets. Further characterization illustrated that such an enhancement on photoreactivity was mainly due to the strengthened light absorption, boosted charge carrier separation, and ~100% exposed {101} facets of the oxygen-deficient dumbbell-shaped anatase mesocrystals. This work will be useful for guiding the synthesis of oxygen-deficient ordered superstructures of metal oxides with desired morphologies and exposed facets for promising applications in environmental remediation.
关键词： photocatalytic performance,{101} facet,oxygen-deficient,anatase mesocrystals,dumbbell-shaped
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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Optimizing one-dimensional TiO2 for photocatalytic hydrogen production from a water-ethanol mixture and other electron donors
摘要： This work is focused on synthesizing and employing one-dimensional (1D) titanium dioxide (TiO2) for hydrogen (H2) production. Based on using electron donors (EDs) (ethanol, methanol, formic acid and 1,2,3 propanetriol), the increased H2 production, when compared to P25 TiO2 nanoparticles, was due to the large specific surface area (SSA) and enhanced electron mobility of 1D TiO2. The impact of the 1D TiO2 synthesis reaction conditions (temperature, NaOH concentration and the TiO2 precursor concentration) on the photocatalytic H2 production rate was evaluated using a 3-factor 3-level Box Behnken design (BBD). The BBD model demonstrated that the temperature and the NaOH concentration significantly affected the 1D TiO2 phase structure, crystal size, SSA, bandgap and the photocatalytic H2 production rate. The phase structure and crystal size of 1D TiO2 were key factors affecting the H2 production rate. 1D TiO2 containing an anatase phase with a mean crystal size of 20.1±0.2 nm was synthesized at 126oC, 15 M NaOH and 49 g·L-1 TiO2. The maximum H2 production rate of 475±12 μmol·h-1 (quantum efficiency (ε) = 20.2±0.5%) for the 1D TiO2 sample was significantly enhanced when compared to commercial TiO2 P25. The H2 production rate for the optimized 1D TiO2 was significantly enhanced by decorating the structure with Pt and Au. Hydrothermal synthesized of 1D TiO2 provided an efficient and low cost method for producing H2 from ethanol, methanol, formic acid and 1,2,3 propanetriol.
关键词： hydrogen production,hydrothermal,1D titanium dioxide,TiO2-B,anatase,photocatalyst,quantum yield
更新于2025-09-23 15:23:52
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Acetic anhydride as oxygen donor in the non-hydrolytic sol-gel synthesis of mesoporous TiO2 with high electrochemical lithium storage performances
摘要： An original, halide-free non-hydrolytic sol-gel route to mesoporous anatase TiO2 with hierarchical porosity and high specific surface area is reported. This route is based on the reaction at 200 °C of titanium (IV) isopropoxide with acetic anhydride, in the absence of a catalyst or of a solvent. NMR studies indicated that this method provides an efficient, truly non-hydrolytic and aprotic route to TiO2. Formation of the oxide involves acetoxylation and condensation successive reactions, both with ester elimination. The resulting TiO2 materials were nanocrystalline, even before calcination. Small (≈10 nm) anatase nanocrystals spontaneously aggregated to form mesoporous micron sized particles with high specific surface area (260 m2 g-1 before calcination). Evaluation of the lithium storage performances showed a high reversible specific capacity, particularly for the non-calcined sample with the highest specific surface area favoring pseudo-capacitive storage: 253 mAh g-1 at 0.1C and 218 mAh g-1 at 1C (C = 336 mA g-1). This sample also showed good cyclability (>92% retention after 200 cycles at 336 mA g-1) with a high coulombic efficiency (99.8 %). Synthesis in the presence of a solvent (toluene or squalane) offers the possibility to tune the morphology and texture of the TiO2 nanomaterials.
关键词： anatase,mesoporous,acetic anhydride route,non-hydrolytic sol-gel,Li-ion batteries
更新于2025-09-23 15:23:52
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EFFECT OF VOLTAGE ON TIO2 NANOTUBES FORMATION IN ETHYLENE GLYCOL SOLUTION
摘要： Anodization of Ti foils in ethylene glycol (EG) containing ammonium fluoride (NH4F), and hydrogen peroxide (H2O2) was carried out to study the effect of voltage on the formation of TiO2 nanotubes. The crystalline phase of the TiO2 nanotubes without further heat treatment were studied. The TiO2 nanotube arrays were produced by anodization of Ti foil at three different voltage; 10, 40, and 60 V in a bath with electrolytes composed of ethylene glycol (EG), ammonium fluoride (NH4F), and hydrogen peroxide (H2O2). The H2O2 is a strong oxidizing agent which was used as oxygen provider to increase the oxidation rate for synthesizing highly ordered and smooth TiO2 nanotubes. Anodization at voltage greater than 10 V leads to the formation of tubular structure where higher anodization voltage (~ 60 V) yield to larger tube diameter (~ 180 nm). Crystallinity of the nanotubes is improved as the voltage was increased. The transformation of amorphous to anatase can be obtained for as anodized TiO2 without any heat treatment. The Raman spectra results show the anodization at 40 V and 60 V gives anatase peak in which confirms the crystalline phase. The stabilization of the crystalline phase is due to the oxygen vacancies and ionic mobilities during the anodization at high voltage.
关键词： anatase,TiO2 nanotubes,crystallization,anodization
更新于2025-09-23 15:23:52
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The Fine Characterization and Potential Photocatalytic Effect of Semiconducting Metal Minerals in Danxia Landforms
摘要： The Danxia landform is representative of the Cretaceous continental red sediment. The careful identi?cation and potential environmental effects of minerals in Danxia red beds have yet to be clearly reported. In this work, reddish sandstone samples were collected from Lang Mountain Danxia landform in Xinning, Hunan province, China, and their mineral phases, element distribution, microstructure, and the spatial relationship of different minerals were investigated using polarizing optical microscope, environmental scanning electron microscopy, energy-dispersive X-ray analysis, electron probe microanalysis, micro-Raman spectra, micro- X-ray diffraction, X-ray ?uorescence spectroscopy, and high-resolution transmission electron microscopy. The results revealed that iron oxide (mainly hematite) and titanium oxide (mainly anatase) were the dominant minerals in Danxia red layers. Microcrystalline hematite was suggested as being the coloring mineral. Anatase, reported here for the ?rst time in Danxia red beds, constituted the content of titanium in the red layer (0.17–0.57%) and was present in a signi?cantly higher amount than the adjacent limestone formation (0.13%). Over 95% of Fe/Ti oxides served as a cementation agent along the framework of coarse-grain minerals (quartz and feldspar). The hematite and anatase were visible-light-responsive semiconductors, with a band gap of 2.01 eV and 3.05 eV, respectively. Photoelectrochemical experiments were performed on synthetic hematite, anatase, and their coupled material. The inactive hematite displayed an enhanced 23-fold photocurrent at 0.8 V (vs. Ag/AgCl) when coupled with anatase. Furthermore, in a photodegradation experiment using methyl orange dye under simulated sunlight, the coupled material showed decolorizing ef?ciency 2.4 times that of hematite. The anatase, therefore, prominently improved the photocatalytic activities of hematite. It is proposed that these semiconducting minerals in red beds produce oxygen reactive species and have signi?cant environmental effects, which is of great importance.
关键词： photocatalysis,anatase,hematite,environmental effect,Danxia landform
更新于2025-09-23 15:22:29
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Photocatalytic activity of anatase titanium dioxide nanostructures prepared by reactive magnetron sputtering technique
摘要： In this work, nanostructured titanium dioxide (TiO2) photocatalysts with high optical and structural homogeneity were successfully synthesized by dc reactive magnetron sputtering technique. The TiO2 thin films were produced with high structural homogeneity without any heat treatment. Analysis of the X-ray diffraction patterns and UV–visible spectroscopy gave an indication that the structure of prepared films is anatase with energy band gap of 3.23 eV. The Fourier-transform infrared spectroscopy has confirmed the formation of Ti–O bond. The average size of TiO2 particles in the deposited films was ranging in 5–7 nm. These nanostructures are very applicable as photocatalysts as their photocatalytic activity was determined from the degradation rate with UV irradiation time as the first order reaction rate constant was determined to be 2.4 × 10?3 min?1.
关键词： Anatase phase,Titanium dioxide,Nanostructures,Photocatalysis
更新于2025-09-23 15:22:29
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Hierarchical rutile/anatase TiO2 nanorod/nanoflower thin film: Synthesis and characterizations
摘要： Hierarchical TiO2 nanorod/nano?ower thin ?lm was synthesized on ?uorine doped tin oxide glass via hydrothermal and aqueous chemistry methods. According to ?eld emission scanning electron microscopy results, the thin ?lm was crack-free and uniform. Primary nanorods had an average diameter of 95 nm and a length of 2 μm. They were perpendicular to the substrate owing to the TiO2 prenucleation. Growth of the nano?owers on the nanorods could increase both the speci?c surface area and roughness. X-ray di?raction and Raman spectroscopy showed that the nanorods were rutile; while the nano?owers were anatase. E?cient electron transfer from anatase to rutile could therefore occur. According to the di?use transmittance spectroscopy examination, the light harvesting rate was ameliorated and the band gap energy reduced to 2.83 eV. This was attributed to the F-doping the sample during synthesis. The enhancement of the photoelectrochemical activity allowed substitution of the TiO2 nanorod/nano?ower thin ?lm for the traditional TiO2 nanorods usually used in solar cells, sensors, and photocatalytic systems.
关键词： Aqueous chemistry,Nanorod array,Rutile/anatase TiO2,Hydrothermal,Nano?ower
更新于2025-09-23 15:22:29
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Mechanistic Study on Facet-Dependent Deposition of Metal Nanoparticles on Decahedral-Shaped Anatase Titania Photocatalyst Particles
摘要： Facet-selective gold or platinum-nanoparticle deposition on decahedral-shaped anatase titania particles (DAPs) exposing {001} and {101} facets via photodeposition (PD) from metal-complex sources was reexamined using DAPs prepared with gas-phase reaction of titanium (IV) chloride and oxygen by quantitatively evaluating the area deposition density on {001} and {101} and comparing with the results of deposition from colloidal metal particles in the dark (CDD) or under photoirradiation (CDL). The observed facet selectivity, more or less {101} preferable, depended mainly on pH of the reaction suspensions and was almost non-selective at low pH regardless of the deposition method, PD or CDL, and the metal-source materials. Based on the results, the present authors propose that facet selectivity is attributable to surface charges (zeta potential) depending on the kind of facets, {001} and {101}, and pH of the reaction mixture and that this concept can explain the observed facet selectivity and possibly the reported facet selectivity without taking into account facet-selective reaction of photoexcited electrons and positive holes on {101} and {001} facets, respectively.
关键词： zeta potential,pH dependence,facet-selective reaction,facet-selective metal photodeposition,{001} and {101} facets,decahedral-shaped anatase titania particles
更新于2025-09-23 15:22:29