4-硝基苄基溴的光照合成方法探索

本文以对硝基甲苯为原料,对4-硝基苄基溴的合成方法进行了探索。通过比较,选择了光照合成方法,并研究了反应的影响因素。反应采用在紫外光照条件下,温度在70～80℃,物料配比为1∶0.6,滴加溴素时间7小时,产品收率可达90%以上,产品纯度可达98%以上。该合成工艺属于环保工艺。

Characterization of nano-Ag/PVP composites synthesized via ultra-violet irradiation

Nano-silver/polyvinylpyrrolidone(PVP)composite materials were successfully synthesized bi-insitu from silver nitrate solution with N-vinyl pyrrolidone (NVP) monomer,containing neither initiator nor reductant, in ultraviolet irradiation conditions.The resultant Ag/PVP nanocomposites were characterized by infrared spectroscopy (FT-IR), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD).TEM show that nano silver particles are homogeneously dispersed in PVP polymer matrix, and the mean size of spherical silver particles is about 5 nm.The spectroscopy of XPS and FTIR showed that there is an interaction between nano silver not only with carbonyl oxygen but also with the nitrogen group within the NVP molecule through the p-π conjugation effect in the nano-silver/PVP composites system.

Microemulsion synthesis and photocatalytic activity of visible light-active BiVO_4 nanoparticles

A water-in-oil microemulsion made up of a cyclohexane/n-hexyl alcohol/Polyethylene glycol tertoctylphenyl/aqueous solution including Bi3+ and VO+3 ions yields the spherical BiVO4 precursors with the size from 5 to 300 nm. Well-crystallized monoclinic scheelite BiVO4 particles with nanometer or micrometer size are fabricated in control by heating microemulsion precursors under various temperatures. The corresponding nucleation and growth process of as-prepared samples has also been investigated via TEM,which demonstrates the detailed morphological evolution of nuclei inside the precursors. As-prepared BiVO4 photocatalysts exhibit enhanced photocatalytic activity under visible-light irradiation in comparison with the bulk BiVO4 prepared by solid-state reaction. The highest RB degrading efficiency of 98% in 180 min under visible-light irradiation is observed for the sample calcined at 600 °C.

Synthesis of Ordered Multivalent Mn-TiO2 Nanospheres with Tunable Size： A High Performance Visible-Light Photocatalyst

A facile and reproducible method has been developed for the synthesis of ordered anatase Mn-TiO2 nanospheres with controllable sizes in the range 200-300 nm by simply varying the amount of manganese（lI） chloride added. The samples were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, scanning electron microscope （SEM）, and transmission electron microscope （TEM） measurements, and it was found that the manganese exists in multivalent forms （Mn4＋/Mn3＋） and substitutes for some of the Ti4＋ in the anatase TiO2 lattice. The presence of Mn significantly influences the morphology and high-temperature stability of TiO2, and extends its light absorption range. Surface photovoltage and photocurrent measurements revealed that an electronic interaction between the Mn and TiO2 was present, in which Mn served as an electron acceptor and effectively inhibited the charge recombination in TiO2; this is thought to be responsible for the highly efficient photocatalytic activity of the material in the degradation of rhodarnine B （RhB） under visible-light irradiation （λ 〉 420 nm）.

Synthesis of novel CaCO_3/Ag_2CO_3/Ag I/Ag plasmonic photocatalyst with enhanced visible light photocatalytic activity.

In this work, novel CaCO3/Ag2CO3/AgI/Ag plasmonic photocatalysts were successfully synthesized by a two-step in situ ion exchange process and their photocatalytic properties were studied. The morphology, crystal structure and optical properties of the as-prepared CaCO3/Ag2CO3/AgI/Ag nanocomposites were characterized by transmission electron microscopy （TEM）, X- Ray diffraction （XRD）, and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the obtained nanocomposites was evaluated by the photodegradation of methyl orange （MO） under visible light irradiation. It was found that the as-prepared CaCO3/Ag2CO3/AgI/Ag plasmonic photocatalyst exhibits high visible light photocatalytic activity. With an optimized composition, MO dye can be decomposed by more than 94% within 15 min under visible light irradiation. Moreover, the photocatalytic stability could be greatly improved upon the addition of Na2CO3 into the photocatalytic system. From the proposed photocatalytic mechanism, the strong surface plasmon resonance effect of Ag nanoparticles and the efficient separation of photogenerated electrons and holes can effectively enhance the photocatalytic performance of the CaCO3/Ag2COj AgI/Ag composites.

Microwave-assisted hydrothermal synthesis of cube-like Ag-Ag_2MoO_4 with visible-light photocatalytic activity

Cube-like Ag-Ag2MoO4 composite has been successfully prepared in the presence of PVP （potyvinylpyrrolidone） via a facile microwave-assisted hydrothermal process. Studies of its photocatalytic performance in the decomposition of RhB indicate that the cube-like Ag-Ag2MoO4 composite exhibits good catalytic activities under visible-light irradiation. The face that Ag pro- motes the absorption of visible light may be attributed to the surface plasmon resonance. Further XRD characterization after recycle photocatalytic tests confirms that partial Ag~ ions in Ag2MoO4 have been reduced to metallic Ag. Reaction temperature, reaction time and the amount of PVP have also been studied and found to play crucial roles in the formation of the cube-like microstructures.