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391.
以Bi(NO3)3·5H2O和NH4VO3为原料,以氯化胆碱和尿素组成的低温离子熔盐为反应介质,采用离子热合成法成功制备出了具有纺锤状外形的BiVO4微米管。利用XRD,SEM,UV-Vis DRS,光催化测试等手段考察了BiVO4颗粒的物相、形貌和光催化性能。结果表明,在离子熔盐环境下可以制备出结晶良好的BiVO4纺锤形微米管,该BiVO4微米管长10~15 μm,直径为1.5 μm左右,管壁厚约为200 nm。同时,研究了pH值对BiVO4颗粒物相与形貌的影响,发现随着pH值的变化可分别合成出具有柱状、纺锤形微米管、柱状微米管和针柱状单斜相BiVO4颗粒。光催化测试结果表明,这些单斜白钨矿BiVO4颗粒在可见光范围都具有一定的光催化活性,其中纺锤状微米管对罗丹明B的降解效果最佳,可见光照射4.5 h后罗丹明B的降解率可达到93%。 相似文献
392.
The electronic structures of BiOX (X = F, Cl, Br, I) photocatalysts have been calculated with and without Bi 5d states using the experimental lattice parameters, via the plane-wave pseudopotential method based on density functional theory (DFT). BiOF exhibits a direct band gap of 3.22 or 3.12 eV corresponding to the adoption of Bi 5d states or not. The indirect band gaps of BiOCl, BiOBr, and BiOI are 2.80, 2.36, and 1.75 eV, respectively, if calculated with Bi 5d states, whereas the absence of Bi 5d states reduces them to 2.59, 2.13, and 1.53 eV successively. The calculated gap characteristics and the falling trend of gap width with the increasing X atomic number agree with the experimental results, despite the common DFT underestimation of gap values. The shapes of valence-band tops and conduction-band bottoms are almost independent of the involvement of Bi 5d states. The indirect characteristic becomes more remarkable, and the conduction-band bottom flattens in the sequence of BiOCl, BiOBr, and BiOI. Both O 2p and X np (n = 2, 3, 4, and 5 for X = F, Cl, Br, and I, respectively) states dominate the valence bands, whereas Bi 6p states contribute the most to the conduction bands. With the growing X atomic number, the localized X np states shift closer toward the valence-band tops, and the valence and conduction bandwidths evolve in opposite trends. Atomic and bond populations have also been explored to elucidate the atomic interactions, along with the spatial distribution of orbital density. 相似文献
393.
394.
The effect of Cl− ions on photooxidation of propylene on TiO2 semiconductor was investigated. Cl−/TiO2 catalysts were prepared by annealing Degussa P25 TiO2 in the gas flow of N2 and Cl2 under 100-400 °C. The photocatalytic oxidation of propylene was carried out in a continuous flow system, with the chromatograph to analyze the products on line. The experimental results showed that the activity of Cl−/TiO2 catalysts increased as heat-treated temperature decreased. The activity of the sample heat-treated at 100 °C was about two times higher than that of pure TiO2. Moreover, as to TiO2, the main product of the propylene photocatalytic oxidation was CO2, but with Cl−/TiO2 catalysts, not only CO2 but also trace CO was determined. The adsorbed species on TiO2 surface before and after reaction were analyzed by X-ray photoelectron spectroscopy (XPS) and thermogravimetric/differential thermal analyses (TG-DTA) coupled to a mass spectrometer (MS). XPS analysis showed that there was Cl− absorbed on the Cl−/TiO2 surface, and the absorption amount of Cl− decreased after the photooxidation reaction of propylene. TG-DTA-MS analysis confirmed chlorine absorbed on the surface of TiO2 in the form of Cl− ion. These results illuminated that absorbed Cl− on the surface of TiO2 formed a weak physical absorption on TiO2 at low temperature, and subsequently participated in the photooxidation of propylene, finally removed from TiO2 surface. 相似文献
395.
采用水热合成法,制备出Er掺杂的BiVO4复合光催化剂,并采用XRD、SEM、XPS和紫外-可见漫反射光谱技术对其进行分析表征.通过可见光下降解水溶液中甲基橙分子来考察其光催化性能,结果显示掺杂组份以氧化物Er2O3形式存在于的复合光催化剂中;且掺杂复合光催化剂的可见光吸收和催化活性都比纯BiVO4有所增强. 相似文献
396.
Titanium dioxide (TiO2) photocatalyst thin films were deposited on non-alkali glass substrates by radio frequency (rf) magnetron sputtering. The Taguchi method with orthogonal array, signal-to-noise ratio and analysis of variance were employed to study the performance characteristics. The experimental studies were conducted under different rf powers, sputtering pressures, O2/(Ar+O2) flow-rate ratios, and substrate temperatures. The deposited TiO2 films were of the anatase phase with a (101) preferred orientation. We performed both photoinduced decomposition of methylene blue (MB) and photoinduced hydrophilicity under UV light illumination. With the optimized TiO2 photocatalyst thin film deposition conditions, the water contact angle after 9 min UV illumination was approximately 5, the absorbance of MB was reduced to 0.2 for 240 min UV irradiation, and the deposition rate was 34.18 Å/min. 相似文献
397.
《应用有机金属化学》2017,31(11)
A novel light‐active magnetic Pd complex as a photocatalyst was prepared through bonding organometallics to mesoporous silica channels formed on the surface of silica‐coated iron oxide nanoparticles. The nanocomposite (denoted as Fe3O4@SiO2@m‐SiO2@PDA‐Pd(0); PDA = 1,10‐phenanthroline‐2,9‐dicarbaldehyde) is more efficient and has higher photocatalytic capability in the degradation of 2,4‐dichlorophenol under visible light irradiation compared with virgin Pd complex (PDA‐Pd). This noteworthy photodegradation activity can be due to the high dispersion of Pd nanoparticles. High yield, low reaction time and non‐toxicity of the catalyst are the main merits of this protocol. Also magnetic separation is an environmentally friendly alternative method for the separation and recovery of the catalyst, since it minimizes the use of solvents and auxiliary materials, reduces operation time and minimizes catalyst loss by preventing mass loss and oxidation. The produced Pd catalyst was characterised using various techniques. Furthermore, transmission electron microscopy characterization was used for determining the structural properties of the Pd nanocatalyst. 相似文献
398.
《应用有机金属化学》2017,31(11)
An electron‐deficient flat 5,10,15‐tris(ethoxycarbonyl)corrole (TECC) cobalt complex, [Co(TECC)(Py)2] ( 1 ; py = pyridine), was prepared and employed as a catalyst for homogeneous hydrogen evolution. It turns out that water can be successfully used as a proton source in acetonitrile–water (2:3 v /v) solvent system for electrocatalytic hydrogen evolution. Complex 1 is also an efficient photocatalyst for hydrogen generation from aqueous solution, an example of the first application of metal corrole as photocatalyst for hydrogen production. 相似文献
399.
A Visible‐Light‐Induced α‐H Chlorination of Alkylarenes with Inorganic Chloride under NanoAg@AgCl
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Shouxin Liu Qi Zhang Huiying Li Yihua Yang Xia Tian Andrew Whiting 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9671-9675
An efficient, photocatalytic chlorination of alkylarene α‐H groups using NaCl/HCl as a chlorine source has been developed, which involves a radical mechanism under visible‐light (including sunlight) conditions. A chlorine radical is proposed to be formed by an electron transfer from chloride ion to O2 in air through the bandgap hole of the semiconductor AgCl. The chlorination protocol is characterized by its use of natural sunlight or other visible light, mild conditions, cheap source of chlorine, green solvent, and high selectivity. The yield of benzylchloride is 95 % with a toluene conversion as high as 40 %, which rivals traditional chlorination methods. 相似文献
400.
《中国化学快报》2020,31(10):2583-2590
Bi/semiconductor photocatalysts have extensively been applied in the production of hydrogen, CO2 reduction and environmental remediation in recent years. This short review summarizes the role of Bi metal as a plasma photocatalyst and cocatalyst. As a cocatalyst, Bi metal can be electron/hole trappers, charge transfer mediators, or oxygen vacancy coordinators. In addition, the preparation methods of the Bi/semiconductor photocatalysts are also reviewed. Challenges and future research directions related to Bi/semiconductor photocatalysts are discussed and summarized, including the use of advanced characterization techniques to refine the reaction mechanism, the difficulties of preparing Bi single atom catalyst, and the improvement of the reduction ability of Bi-based photocatalysts. This review helps understand the reaction mechanisms of the composite photocatalytic systems containing Bi metal and proposes new perspectives for designing the photocatalysts which can control air pollution via a reductive process. 相似文献