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1.
Melamine was added to the precursor of TiO2, then TiO2 prepared by hydrothermal, while melamine was modified. Subsequently, a series of Z-scheme TiO2/g-C3N4 heterojunction composites were successfully synthesized by simple calcination. The morphology and structure of samples were characterized by XRD, FT-IR, UV–vis DRS, SEM, TEM, PL and BET. The photocatalytic activity of these samples has been investigated by degradation of Rhodamine B (RhB), and results indicated that photocatalytic activity of the as-prepared samples was greatly influenced by the content of titanium tetrabutoxide in precursors and the hydrothermal time. The degradation rate of TiO2/g-C3N4-1 to RhB was the best, which was 5.05-fold of pure TiO2 (19.61%) and 2.25-fold of bulk g-C3N4 (44.06%), respectively. The trapping experiment results showed that ·O2? and h+ were main active species during degradation of RhB. The photocatalytic activity of the sample did not decrease significantly after 4 cycles. The unique Z-scheme heterojunction between TiO2 and g-C3N4 improved photocatalytic activity of the samples under visible light. 相似文献
2.
采用三种不同的氮源溶剂热合成了锐钛矿-板钛矿混晶的N-TiO2催化剂.采用X射线衍射、N2吸附-脱附、X射线光电子能谱和透射电子显微镜等手段对催化剂进行了表征.重点研究了不同氮源对催化剂的相组成、晶粒尺寸、微观结构以及比表面积的影响.采用紫外光降解气相苯测试了合成材料的催化活性.结果表明,以水合肼为氮源合成的N-TiO2表现出最优的光催化活性,其活性明显高于P25,且能够循环使用15次以上.采用气相色谱-质谱技术分析了光降解过程的中间产物,基于此提出了相应的降解机理. 相似文献
3.
通过无模板、无助剂的可控水热法, 制备出球形、花形和线状钒酸铋(BiVO 4), 研究了其光学和可见光催化性能. 通过X射线衍射(XRD)和透射电镜(TEM)观测其结构和形貌特征. XRD谱线显示, 所制备的样品为单斜晶体结构. TEM结果表明, 通过控制水热过程的反应参数可以得到不同形貌的纳米粉体. 基于不同条件下制备的样品的微结构分析, 提出了这些不同形貌的形成机制. 紫外-可见漫反射光谱(UV-Vis DRS)表明BiVO 4样品的带隙能约为2.19-2.33 eV. 利用可见光(λ>420 nm)照射下的罗丹明B(RhB)降解实验评价了BiVO 4样品的光催化性能. 结果表明, BiVO 4的光催化活性比商用TiO 2催化剂P25 和掺氮TiO 2 (N-TiO 2)高得多. 所制备的球形BiVO 4光催化效率最高, 经可见光照射180 min, RhB溶液的降解率可达100%. 系统地研究了结构和形貌对不同pH值下制备的BiVO 4样品光催化活性的影响. 相似文献
4.
The photocatalytic activity of TiO 2 nanofibers immobilized on quartz substrates was investigated by evaluating the decomposition of organic pollutants. TiO 2 nanofibers were synthesized by electrospinning the Ti-precursor/polymer mixture solution, followed by hot-pressing for enhancing
the adhesion of TiO 2-nanofiber films to the substrates. TiO 2 started to crystalize in the anatase form at 500 °C and reached the optimal photocatalytic anatase/rutile phase ratio of
70:30 at a calcination temperature of 600 °C. The TiO 2-nanofiber film was demonstrated to be an efficient photocatalyst by ranitidine decomposition under UV illumination and was
proven to have a comparable photocatalytic activity with the well-known Degussa P25 nanoparticulate photocatalyst and excellent
recyclability during 10 cycles of photocatalytic operation, indicating no loss of TiO 2 nanofibers during photocatalytic operations. 相似文献
5.
Visible‐light‐driven plasmonic photocatalyst Ag‐TiO 2 nanocomposite hollow spheres are prepared by a template‐free chemically‐induced self‐transformation strategy under microwave‐hydrothermal conditions, followed by a photochemical reduction process under xenon lamp irradiation. The prepared samples are characterized by using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, N 2 adsorption‐desorption isotherms, X‐ray photoelectron spectroscopy, UV/Vis and Raman spectroscopy. Production of ?OH radicals on the surface of visible‐light illuminated TiO 2 was detected by using a photoluminescence method with terephthalic acid as the probe molecule. The photocatalytic activity of as‐prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) aqueous solution at ambient temperature under visible‐light irradiation. The results show that the surface plasmon absorption band of the silver nanoparticles supported on the TiO 2 hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag‐TiO 2 nanocomposite sample was observed. The prepared nanocomposite hollow spheres exhibits a highly visible‐light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of pure TiO 2 and commercial Degussa P25 (P25) powders. Especially, the as‐prepared Ag‐TiO 2 nanocomposite hollow spheres at the nominal atomic ratio of silver to titanium ( R ) of 2 showed the highest photocatalytic activity, which exceeds that of P25 by a factor of more than 2. 相似文献
6.
Powders containing mixtures of titania and molybdite in different ratios were prepared by sol–gel processing. The sols were dried and subsequently calcined at 300, 500 and 700 °C. Depending on the ratio of Ti and Mo in the initial sol and the calcination temperature, Ti-doped MoO 3, TiO 2/MoO 3 or Mo-doped TiO 2 have been formed. The as prepared samples were characterised by scanning electron microscopy with attached X-ray dispersive energy analysis, X-ray diffractometry, Raman spectroscopy, gas adsorption and optical characterisation by ultraviolet/visible spectroscopy. The latter was used for the analysis of the photocatalytic properties on the decolourisation of methylene blue solutions under visible light irradiation. The phase composition, the specific surface and the photocatalytic activity were influenced by the molybdenum content and the calcination temperature. The final molybdenum content in the samples additionally depends on the calcination temperature. The optimum photocatalytic properties were observed or Ti-doped MoO 3. 相似文献
7.
Developing efficient and cheap photocatalysts that are sensitive to indoor light is promising for the practical application of photocatalysis technology. Here, N-doped TiO 2 photocatalyst with loaded Cu crystalline cocatalyst is synthesized by a simple one-pot method. The structure is confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy analysis, which exhibit that Cu metal nanocrystalline is uniformly deposited on the surface of N-doped TiO 2 material. UV-Vis absorption spectra illustrate that the modified samples possess favorable visible light absorption properties and suppressed-electron hole separation. The as-fabricated Cu-loaded N-TiO 2 materials show high activity in photocatalytic decomposing isopropanol and inactivating E. coli under the irradiation of a household white LED lamp. The developed synthetic strategy and photocatalytic materials reported here are promising for indoor environment purification. 相似文献
8.
TiO 2 nanocrystallites were prepared from precursors tetra- n-butyl titanate (Ti(OC 4H 9) 4) and titanium tetrachloride (TiCl 4). The precursors were hydrolyzed by gaseous water in autoclave, and then calcined at predetermined testing temperatures. The samples were characterized by X-ray diffraction (XRD), thermogravimetry–differential thermal analysis (TG–DTA), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectra (FT-IR), and UV–vis diffuse reflectance spectra (DRS). The photocatalytic activities of the samples were evaluated by the photobleaching of methylene blue (MB) in aqueous solution and the photocatalytic oxidation of propylene in gas phase at ambient temperature. The results showed that the anatase phase nanocrystalline TiO 2 could be obtained at relatively low temperatures (for precursor Ti(OC 4H 9) 4 at 110 °C and for TiCl 4 at 140 °C, respectively), and that the as prepared samples exhibited high photocatalytic activities to photobleach MB in aqueous solution. As the calcination temperatures increasing, the decolor ratio of MB increased and reached the maximum value of nearly 100% at 600 °C, and then decreased. The photobleaching of MB by all samples followed the pseudo-first-order kinetics with respect to MB concentration. The photodecomposition amount of propylene by TiO 2 nanocrystallites calcined at 600 °C from precursor of Ti(OC 4H 9) 4 is 21.6%, which is approaching to that by Degussa P25 TiO 2 (24.9%). 相似文献
9.
TiO 2 photocatalytic powders were synthesized by a sol–gel combustion synthesis method in which urea was used as the fuel and titanyl
nitrate was used as the oxidizer. Various fuel-to-oxidizer ratios were studied for their effects on the combustion phenomena
and the properties of the synthesized TiO 2. The fuel-to-oxidizer ratio was found to determine the maximum combustion temperature, which in turn affects the specific
surface area, crystallite size, and weight fraction of anatase phase of the synthesized TiO 2. The synthesized TiO 2 all contain carbonaceous species and are either pure anatase or anatase–rutile mixed phase in crystalline structure. The
photocatalytic activity of the TiO 2 was found to correlate to a certain degree with the specific surface area, crystallite size, weight fraction of anatase phase,
and visible and IR absorbances. The mixed phase TiO 2 shows a higher photocatalytic activity than the pure anatase phase TiO 2 when containing a small fraction (<~25 wt%) of rutile phase but a lower phoyocatalytic activity when containing a large fraction
(>~25 wt%) of rutile phase. The synthesized TiO 2 all show higher photocatalytic activity than Degussa P25 TiO 2. The enhanced photocatalytic activity was attributed mainly to sensitization by the carbonaceous species and larger amounts
of hydroxyl group adsorbed on the TiO 2 surface. 相似文献
10.
The photocatalytic degradation for some kinds of dye-constituent aromatics with TiO 2 in the presence of phosphate anions in aqueous dispersion was investigated under both visible light (λ>480 nm) and UV irradiation. The influences of phosphate anion upon the degradation of organics under these different conditions was revealed by the measurement of point of zero ξ-potential ( P ZC) of TiO 2, UV-VIS spectra, HPLC and LC-MS. The adsorption and photodegradation of some organics, which adsorb on the surface of TiO 2 by a dominating group bearing a positive charge, was enhanced, while that of others, which adsorb on the surface of TiO 2 by a dominating group bearing negative charge, was depressed by the presence of phosphate anions under UV irradiation at the experimental conditions (pH 4.3). It was confirmed that better adsorption of organics on the surface of TiO 2 had an advantage in their photocatalytic degradation under UV irradiation. On the other hand, although the adsorption of rhodamine B (RhB) and methylene Blue (MB) markedly increased, their degradation under visible light irradiation was depressed in the presence of phosphate anions. It is suggested that phosphate anion greatly blocked the electron transfer from excited RhB and MB molecules as RhB and MB molecules predominantly adsorbed on the surface of TiO 2 through the electrostatic interaction with surface adsorbed phosphate anions. 相似文献
11.
Nanocrystalline titanium dioxide (TiO 2) powders have been synthesized by sol–gel method using titanium tetrachloride (TiCl 4) or tetrabutyl titanate (Ti(OC 4H 9) 4 as precursors, different alcohols and calcination temperatures in the range from 400 to 650 °C. The photocatalytic activity
of as-prepared powders has been tested for the degradation of metoprolol tartrate salt, a selective β-blocker used to treat
a variety of cardiovascular diseases, and compared to photocatalytic activity obtained from Degussa P25. Nanosized TiO 2 powders prepared from TiCl 4 and amyl-alcohol, calcined at 550 °C, displayed an activity comparable to Degussa P25, whereas the sample from the same series,
calcined at 650 °C, showed higher photocatalytic activity in the whole range of the catalyst loading. Structural, morphological
and surface properties of synthesized TiO 2 nanopowders have been investigated by XRD, SEM, EDS and BET measurements, as well as FTIR and Raman spectroscopy, in order
to find out the material properties which enable rapid an efficient decomposition of metoprolol under UV radiation. 相似文献
12.
The effects of a room temperature ionic liquid, 1-butyl-3-methylimidazolium terafluoroborate ([Bmim]BF 4), on the photocatalytic performance of Degussa P25 TiO 2 were investigated. Also, the photocatalysis mechanism was systematically analyzed by conducting different reactive radical trapping experiments. The results showed that photogenerated electrons were the main reactive species involved in the photocatalytic degradation of methyl orange (MO), while ?OH radicals and photogenerated holes played an important role in the photocatalytic decomposition of rhodamine B (RhB). The addition of ionic liquid (IL) could slightly enhance the photocatalytic degradation rate of MO because adsorption of [Bmim] + ions on the TiO 2 surface not only enhanced traping and transfer of photogenerated electrons, but also facilitated adsorption of negatively charged MO. On the contrary, IL suppressed the degradation rate of RhB because [Bmim] + on the TiO 2 surface not only hindered the access of positively charged RhB to TiO 2, but also restricted the diffusion of positively charged holes to the TiO 2/solution interface. 相似文献
13.
Nanocrystalline TiO 2 was synthesized using the microwave plasma technique and characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, laser particle size analyzer, UV–vis spectroscopy and BET surface area analyzer. The synthesized TiO 2 powder crystallized in anatase phase and the crystallite sizes were in nanometers. The photocatalytic activity of the compound was determined and compared against the activity of the commercial Degussa P-25 TiO 2 catalyst. The degradation rates of the dyes were found to be higher over the synthesized TiO 2 as compared to that over commercial Degussa P-25 TiO 2. 相似文献
14.
Core–shell structured Fe 3O 4/SiO 2/TiO 2 nanocomposites with enhanced photocatalytic activity that are capable of fast magnetic separation have been successfully synthesized by combining two steps of a sol–gel process with calcination. The as‐obtained core–shell structure is composed of a central magnetite core with a strong response to external fields, an interlayer of SiO 2, and an outer layer of TiO 2 nanocrystals with a tunable average size. The convenient control over the size and crystallinity of the TiO 2 nanocatalysts makes it possible to achieve higher photocatalytic efficiency than that of commercial photocatalyst Degussa P25. The photocatalytic activity increases as the thickness of the TiO 2 nanocrystal shell decreases. The presence of SiO 2 interlayer helps to enhance the photocatalytic efficiency of the TiO 2 nanocrystal shell as well as the chemical and thermal stability of Fe 3O 4 core. In addition, the TiO 2 nanocrystals strongly adhere to the magnetic supports through covalent bonds. We demonstrate that this photocatalyst can be easily recycled by applying an external magnetic field while maintaining their photocatalytic activity during at least eighteen cycles of use. 相似文献
15.
考察了Pt促进的N掺杂TiO2(Pt/N-TiO2)催化剂对光催化降解有机污染物性能的影响及其作用本质.采用X射线衍射、透射电镜、X射线光电子能谱、紫外-可见漫反射光谱、光电化学和荧光光谱等手段对催化剂进行了表征,并考察了样品在可见光下光催化降解甲基橙(MO)的反应性能.结果表明,Pt的存在并未明显改变N-TiO2的晶... 相似文献
16.
通过阳极氧化法和电化学沉积制备了TiO_2/CdSe异质结膜,并通过旋涂结合后续热处理的方法,在TiO_2/CdSe异质结膜上制备适量脱水态的聚乙烯醇(PVA)来提高TiO_2/CdSe异质结抗光腐蚀性能。采用XRD,SEM,FTIR,UV-Vis,PL,电化学测试,光催化降解罗丹明B等方法对样品的晶体结构、微观形貌、光电化学性能、光催化性能等进行了表征,并通过测定光降解体系中Cd2+的浓度,研究了纳米复合材料的抗光腐蚀性能。结果表明,与TiO_2/CdSe相比,TiO_2/CdSe/PVA纳米复合材料不仅具有更好的可见光光催化活性,还具有良好的可见光光催化稳定性和抗光腐蚀性能。同时,PVA的存在对光催化反应中的二次污染物Cd2+也有抑制作用。 相似文献
17.
以钛酸丁酯为前驱体, 碘溶胶为碘源, 在室温下采用水解沉淀法制备了单质碘和纳米TiO 2复合的双介孔结构光催化剂(M-I 2-TiO 2). 采用X射线衍射(XRD)、透射电子显微镜(TEM)、比表面分析(BET)、紫外-可见(UV-Vis)漫反射光谱和傅里叶变换-红外光谱(FT-IR)对M-I 2-TiO 2进行了表征. 以次甲基蓝(MB)溶液为模拟废水, 对M-I 2-TiO 2的光催化性能进行了评价, 研究了不同热处理温度对光催化活性的影响. 结果表明, M-I 2-TiO 2在可见光区有显著的吸收, 300 ℃热处理得到的样品比表面积高达227.6 m 2/g, 600 ℃热处理所得样品的比表面积仍高达111.8 m 2/g, 而400 ℃热处理所得样品具有最好的光催化降解性能. 双介孔结构纳米TiO 2/I 2复合材料的光催化降解性能显著高于相同方法制备的纯TiO 2和Degussa P-25商业产品. 催化剂经6次重复使用其光催化活性基本保持不变. 相似文献
18.
In this work bimodal structured titanium dioxide (TiO 2) microsphere has been prepared from commercial TiO 2 powder and nano-sized titania gel via sol–gel spray-coating technique. Crystallization and transformation behavior of titania gel were investigated. The results revealed that the crystallization and transformation of anatase particles were substantially affected by the concentration of solvent and calcination temperature. Anatase crystallite size of 10 nm was obtained at mole ratio of solvent/precursor 50/1 and calcination temperature of 450 °C. The prepared nano-sized titania gel was embedded within the core (commercial TiO 2, P25) during the spraying process. The prepared TiO 2 microsphere was characterized using X-ray diffractometer (XRD), scanning electron microscope (SEM), field emission electron microscope (FESEM) and micropore analysis. The photocatalytic activity was monitored by following the degradation of phenol with activity benchmarked against commercial P25 (Degussa). The increase of photocatalytic activity of TiO 2 microsphere was attributed to the nano-sized anatase crystallite which has been incorporated into the TiO 2 microsphere. 相似文献
19.
Exploiting advanced photocatalysts under visible light is of primary significance for the development of environmentally relevant photocatalytic decontamination processes. In this study, the ionic liquid (IL), 1‐butyl‐3‐methylimidazolium tetrafluoroborate, was employed for the first time as both a structure‐directing agent and a dopant for the synthesis of novel fluorinated B/C‐codoped anatase TiO 2 nanocrystals (T IL) through hydrothermal hydrolysis of tetrabutyl titanate. These T IL nanocrystals feature uniform crystallite and pore sizes and are stable with respect to phase transitions, crystal ripening, and pore collapse upon calcination treatment. More significantly, these nanocrystals possess abundant localized states and strong visible‐light absorption in a wide range of wavelengths. Because of synergic interactions between titania and codopants, the calcined T IL samples exhibited high visible‐light photocatalytic activity in the presence of oxidizing Rhodamine B (RhB). In particular, 300 °C‐calcined T IL was most photocatalytically active; its activity was much higher than that of TiO 1.98N 0.02 and reference samples (T W) obtained under identical conditions in the absence of ionic liquid. Furthermore, the possible photocatalytic oxidation mechanism and the active species involved in the RhB degradation photocatalyzed by the T IL samples were primarily investigated experimentally by using different scavengers. It was found that both holes and electrons, as well as their derived active species, such as .OH, contributed to the RhB degradation occurring on the fluorinated B/C‐codoped TiO 2 photocatalyst, in terms of both the photocatalytic reaction dynamics and the reaction pathway. The synthesis of the aforementioned novel photocatalyst and the identification of specific active species involved in the photodegradation of dyes could shed new light on the design and synthesis of semiconductor materials with enhanced photocatalytic activity towards organic pollutants. 相似文献
20.
Bimodal mesoporous TiO 2 microspheres with high photocatalytic activity were prepared by a hydrothermal method using titanium sulfate as precursor in the presence of urea. The results indicate that all prepared samples show bimodal pore-size distributions in the mesoporous region: smaller intra-aggregated pores with peak pore diameter of ca. 2 nm and larger inter-aggregated pores with peak pore diameter of ca. 12.5 nm. The molar ratio of urea to Ti(SO 4) 2 ( Ru) has an obvious influence on the morphology, microstructure and photocatalytic activity of TiO 2. With increasing Ru, specific surface areas and porosity increase, contrarily, the crystallite size and relative anatase crystallinity decrease. The photocatalytic activity first increases with Ru. At Ru = 2.0, the photocatalytic activity reaches the highest and is obviously higher than that of Degussa P25. With further increasing Ru, the photocatalytic activity decreases. The formation rate of hydroxyl radicals during photocatalysis has a positive correlation with the photocatalytic activity. 相似文献
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