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Enhanced photoelectrochemical performance of CdO-TiO2 nanotubes prepared by direct impregnation
摘要： A direct impregnation technique was adopted to prepare a series of CdO-TiO2 nanotubes. Self-organized TiO2 nanotubes were prepared using an optimized two-step anodization process. The morphology, crystallinity, elemental composition, and photoelectrochemical properties of the CdO-TiO2 nanotubes were characterized by scanning electron microscopy (SEM), transimission electron microscopy (TEM), UV-Vis diffuse reflection spectra (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and photoelectric cell (PEC) measurements. At lower Cd(NO3)2 concentration, no obvious CdO crystalline particle formed on the TiO2 NTbs surface, while the EDS and XPS measurements shows the increasing doping amount of CdO as the Cd(NO3)2 concentration increasing. At a relatively high precursor concentration (800 mM), the formation of particle clusters and nanocrystals on the surface of the TiO2 nanotubes could be easily detected, and the sample presented XRD diffraction peaks indicative of CdTiO3. Meanwhile, the Ti 2p XPS spectra displayed an obvious shift (~0.3 eV), which could be attributed to the change in the lattice structure. A negative shift in the flatband potential (Vfb) and a decrease in charge carrier density were observed after doping. The maximum incident photon to charge carrier efficiency (IPCE) value calculated for the CdO-TiO2 nanotubes was 10.16%, much higher than that of pure TiO2 nanotubes.
关键词： Cadmium oxide,Photoelectrochemical,Impregnation-Calcination,TiO2 nanotubes
更新于2025-09-23 15:23:52
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Effects of Calcination Temperature on Morphology and Structure of CeO2 Nanofibers and their Photocatalytic Activity
摘要： Calcination temperature plays a critical role on morphology and structure of CeO2 nanofibers, thus affecting its photocatalytic activity. CeO2 nanofibers with diameter of 95 nm were successfully fabricated by electrospinning combining with calcination. The calcination temperature was determined by TGA results ranging from 500℃ to 800℃. The morphology and structure of samples obtained with different calcination temperatures, have been characterized by SEM and XRD. Meanwhile, the specific surface area of samples were checked by BET, that was decreased 17 times from 56.3 m2/g to 3.3 m2/g, as the temperature increasing from 500℃ to 800℃. Normally, the higher specific surface area, the more efficiency photocatalytic activity. But it was interesting that the photodegradation rate of methylene blue was increased from 67% to 98% for CeO2 catalyst obtained at 500℃ and 800℃, with 4 times higher kinetic constant reaction rate under UV irradiation for 60 min. It demonstrates that the photocatalytic activity of CeO2 nanofibers catalyst is not directly related to the specific surface area, and increasing the calcination temperature has a positive effect for the photocatalytic efficiency.
关键词： Calcination,Porous Materials,Microstructure,CeO2 Nanofiber,Photocatalysis
更新于2025-09-23 15:23:52
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Eu-Doped BaF2 Nanoparticles for Bioimaging Applications
摘要： Pure Eu3+ ion doped BaF2 nanoparticles with tunable properties or property combinations are accessible via an ionic liquid-assisted solvothermal method. Structural parameters such as cell parameters, lattice strain and especially morphology are judiciously tuned with calcination temperatures. For example, tensile strain is observed in samples calcined up to 400oC, however compressive strain appears in samples calcined at 600oC and beyond. Larger surface area up to the sample calcined at 400oC and observation of layer structure at higher calcinations temperature (650oC and beyond) have been rationalized based on secondary nucleation. 3-dimensional island-like morphology with step-like layer structure caused by secondary nucleation and self-assembly are visualized and explained by Scanning Electron Microscope analysis. Moreover, emission intensity, decay time, quantum yield and Judd-Ofelt parameter of the Eu3+ ions increase systematically with calcinations temperature to a maximum at 400oC, above which they decrease and finally vanish at 800oC. Our results suggest that, smaller sized nanoparticles with 3-dimensional island-like structures, generated due to secondary nucleation at higher calcinations temperature may cause the increase of surface defects and subsequent luminescence quenching. To the best of our knowledge, the interplay between calcinations and secondary nucleation followed by drastic changes in the luminescence properties is new and previously unreported for the nanopowders. In addition, to improve the dispersibility, as-prepared nanoparticles are coated with silica and solubility of nanoparticles is measured in different solvents so that it can be useful for bio-imaging applications also.
关键词： calcination,photoluminescence,rare-earth ion,secondary nucleation,nanoparticles
更新于2025-09-23 15:23:52
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Conductive TiO2 nanorods via surface coating by antimony doped tin dioxide
摘要： Titanium dioxide (TiO2) has been widely used as the white pigment in paintings and coatings. It is of significance to endow TiO2 powders with the high conductivity to extend its application. In this research, rutile TiO2 nanorods were prepared as the substrate material. Further the surface coating by antimony doped tin dioxide (SbeSnO2) shell layers was achieved to obtain conductive TiO2 nanorods. The morphology and structure of TiO2@SbeSnO2 nanorods was mainly focused on to obtain high conductivity by optimizing the calcination temperature. When the temperature was properly applied at nearly 500 °C, the calcination led to the fusion and attachment of SbeSnO2 crystalline regions on the surface of TiO2 nanorods, forming a continuous intact coating layer and thus getting lower volume electrical resistivity of the composite nanopowder. However, after calcination at 600 °C or higher temperature, the integrity of SbeSnO2 shell layers would be destroyed, resulting in the increased electrical resistivity. The conductive TiO2 nanorods obtained at the optimized reaction condition showed a very low resistivity of 52 ± 1.6 Ω cm, in contrast to 105 Ω cm of the pure TiO2. The conductive TiO2 nanorods would be excellent candidate for antistatic or electromagnetic shielding applications in coatings.
关键词： Core-shell,Calcination,Titanium dioxide,Conductive
更新于2025-09-23 15:22:29
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Optimization of the Pt Nanoparticle Size and Calcination Temperature for Enhanced Sensing Performance of Pt-Decorated In2O3 Nanorods
摘要： The surface-to-volume ratio of one-dimensional (1D) semiconductor metal-oxide sensors is an important factor for achieving good gas sensing properties because it offers a wide response area. To exploit this effect, in this study, we determined the optimal calcination temperature to maximize the specific surface area and thereby the sensitivity of the sensor. The In2O3 nanorods were synthesized by using vapor-liquid-solid growth of In2O3 powders and were decorated with the Pt nanoparticles by using a sol-gel method. Subsequently, the Pt nanoparticle-decorated In2O3 nanorods were calcined at different temperatures to determine the optimal calcination temperature. The NO2 gas sensing properties of five different samples (pristine uncalcined In2O3 nanorods, Pt-decorated uncalcined In2O3 nanorods, and Pt-decorated In2O3 nanorods calcined at 400, 600, and 800 ?C) were determined and compared. The Pt-decorated In2O3 nanorods calcined at 600 ?C showed the highest surface-to-volume ratio and the strongest response to NO2 gas. Moreover, these nanorods showed the shortest response/recovery times toward NO2. These enhanced sensing properties are attributed to a combination of increased surface-to-volume ratio (achieved through the optimal calcination) and increased electrical/chemical sensitization (provided by the noble-metal decoration).
关键词： Calcination,Pt decoration,Gas sensor,In2O3,NO2
更新于2025-09-23 15:21:21
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Silica-coated nanocrystalline TiO2 with improved thermal stability
摘要： Deposition of a SiO2 coating on anatase TiO2 nanocrystals is shown to improve their thermal stability. As low as 0.5% Si was shown to preserve the small anatase crystallite size after calcination at 600 °C. Such treatment led to considerable sintering of TiO2 nanocrystals without the silica with the average particle size growth from 9 to 50 nm, surface area decrease from 135 to 22 m2/g and partial anatase conversion to rutile. The phase composition, crystallite size, and surface area of 5%Si-TiO2 samples were largely preserved till the temperatures as high as 800 °C whereas the anatase phase was mostly stably even after calcination at 1000 °C. The phase transformation from anatase to rutile in xerogel TiO2 and TiO2@SiO2 samples apparently did not occur until the crystallites grew larger than the critical size about 50 nm. Electron-acceptor sites capable of ionizing perylene to its radical cations were observed on all samples with anatase crystalline structure. So, the silica shell deposition improves the TiO2 thermal stability without limiting access to the surface active sites.
关键词： B. Porosity,D. TiO2,Electron Paramagnetic Resonance,A. Calcination
更新于2025-09-23 15:21:21
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Inorganic and Composite Fibers || Photocatalytic Properties of TiO2 Composite Nanofibers Electrospun With Different Polymers
摘要： Electrospinning offers the possibility to create fibers with very fine diameters. Spinning ultrafine fibers with diameters in the range of some hundred nanometers from melt or solution has been established some decades ago. With electrospinning, depending on the exact technology, either continuous fibers or fiber mats with relatively narrow diameter distributions can be created from a broad range of materials, starting from polymers to composites and even ceramics. Due to their large inner surface area, nanofiber mats are typically used as filter materials, catalyzers, medical wound dressing, or for promotion of cell growth in biomedical applications. Electrospinning ceramic nanofibers can be performed by co-spinning a blend of polymer and ceramic precursor, followed by calcination to remove the polymer matrix and keep only the ceramic fibers. Alternatively, ceramic nanoparticles can be bonded on the surfaces of polymer nanofibers, or hybrid nanofibers can be formed, consisting of ceramic and polymer materials. In this way, electrospinning can be used to produce a broad variety of nanofibers, besides other typical methods such as self-assembly, use of templates, or drawing, for applications in life sciences, energy storage, dye-sensitized solar cells (DSSCs), electronic and magnetic devices, bonding, etc.
关键词： TiO2 nanofibers,Electrospinning,photocatalytic properties,calcination,polymer composites
更新于2025-09-23 15:21:01
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Influence of Calcination Temperature on the Performance of TiO<sub>2</sub> Films in Dye-Sensitized Solar Cells
摘要： In this work, the effects of calcination temperature on the photovoltaic performance of TiO2 films prepared with non-hydrolytic sol-gel method were reported. The optimal photovoltaic performance of DSCs was obtained by annealing TiO2 film at 550 °C. The short-circuit current (Jsc), open-circuit voltage, fill factor (FF) and energy conversion efficiency were 15.68 mA·cm-2, 0.71 V, 0.62 and 6.83%, respectively.
关键词： dye-sensitized solar cell,photoanode film,performance,calcination temperature,non-hydrolytic sol-gel titanium dioxide
更新于2025-09-16 10:30:52
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Phase Transition of SiO <sub/>2</sub> Nanoparticles Prepared from Natural Sand: The Calcination Temperature Effect
摘要： In this paper, we systematically report the synthesis of nano silica powder from natural silica sand by a continuous process. Extraction of sodium silicate from silica sand was through a hydrothermal process, then sodium silicate was ready to be used as a precursor in the form of silicate slurry by coprecipitation process. The silicate slurry of SiO2.XH2O was then dried in a furnace at 150 °C for 4 hours until obtaining a pure white SiO2 powder. At a calcination temperature of 900 °C, the sample was then tested by XRD to analyze the transformation of the crystal phase of SiO2 nanoparticles. Identification of functional group absorption was undertaken by FTIR test, and the particle grain microstructure was analyzed by SEM. At calcination temperature of 900 °C, the SiO2 silica nanoparticles experienced a change of phase from amorphous to crystal or amorphous-cristobalite phase; a shift in stiffness for positions of functional group absorption of Si-O stretching or LO functional groups, Si-O stretching or TO, Si-O-Si bending and Si-O-Si rocking and OH-functional groups occurred; the growth of particle grains happened with a spherical and oval trend, with a larger size. SiO2 nanoparticles were successfully synthesized by a continuous method and 900 °C calcination temperature had a significant effect on structural phase changes, the formation of siloxane functional groups, silanol, and grain growth on SiO2 nanoparticles.
关键词： calcination,nanoparticle,amorphous,cristobalite,natural sand,Silica
更新于2025-09-11 14:15:04
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Synthesis and characterization of SDS assistant α-alumina structures and investigation of the effect of the calcination time on the morphology
摘要： In this paper, α-alumina structures were successfully prepared via hydrothermal synthesis supported with sodium dodecyl sulfonate anionic surfactant. The effect of the surfactant and the calcination time were investigated. The characterization of the samples calcinated at 1200 °C was performed using Raman spectroscopy, X-Ray Difraction analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy techniques. Experimental results showed that pure α-Al2O3 structures were obtained with different morphologies.
关键词： Hydrothermal synthesis,Calcination,Morphology,Sodium dodecyl sulfonate,Alumina
更新于2025-09-10 09:29:36