梳状丙烯酸酯类共聚物凝胶电解质的传输性能与自由体积

用三种分子量大小不等的聚乙二醇单甲醚(PEGME)与甲基丙烯酸甲酯-马来酸酐共聚物[P(MMA-co-MAh)]反应,制备了三种支链长度不等的梳状共聚物(MMA/MAh-g-PEGME), 并以此为基体, 加入增塑剂碳酸丙烯酯(PC)和高氯酸锂(LiClO₄), 采用溶剂浇铸法制备了三种凝胶聚合物电解质(GPE)膜, 研究了其离子传输性能, 发现该聚合物凝胶电解质的离子传输机理符合VTF (Vogel-Tamman-Fulcher)方程, 即离子传输性能与凝胶体系自由体积的大小有关; 采用正电子湮没寿命谱仪(PALS)研究了GPE 体系的自由体积特性, 获得了各支链长度不同的共聚物凝胶电解质的自由体积分数, 分析各自由体积与离子传输性能之间的关系, 建立了共聚物结构、凝胶聚合物自由体积及其传输性能之间的关系. 发现梳状共聚物支链长度越长, 凝胶电解质的自由体积越大, 离子传输性能越高.     

Effect of Cesium Modification on CuO/CeO2 Catalysts for the Catalytic Decomposition of N2O

A series of Cs-modified CuO/CeO2 mixed oxide catalysts was prepared for enhancing the stable activity of N2O decomposition.It was found that Cs modification promoted the catalytic performance of CuO/CeO2 catalysts significantly,The l%Cs-CuO/CeO2 catalyst exhibited the best activity,and the conversion of N2O reached 100%at 380℃ in the presence of 2% O2.The catalytic behaviors were investigated by means of XRD,N2 adsorption isotherms,XPS,H2-TPR(TPR:temperature-prograrmmed reduction),CO-IR,O2-TPD(TPD:temperature-programmed desorption)and diffused reflectance infrared Fourier transform spectorscopy(DRiFTs).The results revealed that Cs modification promoted the activity and the oxygen resistance by enhancing the desorption of surface oxygen species and increasing the content of Ce^3+.CO-DRIFTs revealed that Ce^3+could efficiently facilitate the regeneration of active Cu^+sites by an oxygen migration step.The possible reaction mechanism was also discussed.     

Au/MXene based ultrafast all-optical switching

All-optical switches have arisen great attention due to their ultrafast speed as compared with electric switches. However, the excellent optical properties and strong interaction of two-dimensional (2D) material MXene show great potentials in next-generation all-optical switching. As a solution, we propose all-optical switching used Au/MXene with switching full width at half maximum (FWHM) operating at 290 fs. Compared with pure MXene, the Au/MXene behaves outstanding performances due to local surface plasmon resonance (LSPR), including broadband differential transmission, strong near-infrared on/off ratio enhancement. Remarkably, this study enhances understanding of Au/MXene based ultrafast all-optical switching red-shifted about 34 nm in comparison to MXene, validating all optical properties of Au/MXene opening the way to the implementation of optical interconnection and optical switching.     

苯甲酸甲酯加氢合成苯甲醛

采用共沉淀法制备了ＭｎＯ２／γ－Ａｌ２Ｏ３催化剂,在常压固定床反应器上研究了苯甲酸甲中氢生成苯甲醛的反应过程,并获得了最佳的反应条件。通过ＸＲＤ,,ＮＨ３－ＴＰＤ和ＣＯ２－ＴＰＤ等技术研究了催化剂的表面特性。结果表明,催化剂的活性发为ＭｎＯ,催化剂表面存在酸中心和碱中心。     

大功率激光单模光纤远距离传输的注入光纤光功率限值分析

对于大功率激光单模光纤远距离传输, 采用传统的受激拉曼散射(SRS)阈值作为注入光纤激光功率值取值过大。本文对单模光纤远距离传输过程中泵浦光和拉曼斯托克斯光(Stokes)光功率随注入光纤激光功率的变化进行仿真与理论分析。根据光纤中SRS产生的机理, 提出以拉曼Stokes光在单模光纤中传输的光功率变化曲线曲率极大值点对应的注入激光功率为限值, 对注入单模光纤光功率限值随着光纤长度变化进行仿真, 通过曲线拟合得出注入单模光纤激光功率限值公式, 并搭建实验系统进行验证。结果表明, 提出的注入单模光纤激光功率限值适用于大功率激光远距离单模光纤传输。     

Formation and photocatalytic properties of nanocomposite films containing both tetracobalt Dawson-derived sandwich polyanions and tetracationic porphyrins

Films based on electrostatic interactions between tetracationic zinc porphyrins, ZnOEP(py)(4)(4+) or ZnTMePyP(4+), and the tetracobalt Dawson-derived sandwich polyanion αββα-[Co(4)(H(2)O)(2)(P(2)W(15)O(56))(2)](16-) are formed by the so-called layer-by-layer method. These films have been characterized by UV-visible absorption spectroscopy, atomic force microscopy and electrochemistry. The composition of the film was measured by X-ray photoelectron spectrum (XPS). The XPS data confirm the presence of the expected elements. The photocatalytic properties of these films have been also studied for the reduction of silver and gold ions. Indeed, in these systems, porphyrins can be excited by visible light and then play the role of photosensitizers able to give electrons to POM known to be good catalysts. Silver nanowires and gold nanosheets have been obtained.     

Decorating multi-walled carbon nanotubes with nickel nanoparticles for selective hydrogenation of citral

The nanocomposites of multi-walled carbon nanotubes (MWNTs) decorated with nickel nanoparticles were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). Due to the strong interaction between Ni²⁺ and –COOH, PAA-g-MWNTs became an excellent supporting material for Ni nanoparticles. The morphology and distribution of Ni nanoparticles on the surface of MWNTs were greatly influenced by the reduction temperatures, the experimental results also showed that the distribution of Ni nanoparticles was greatly improved while the MWNTs were modified by poly(acrylic acid) (PAA). The hydrogenation activity and selectivity of MWNTs decorated with Ni nanoparticles (Ni-MWNTs) for α, β-unsaturated aldehyde (citral) were also studied, and the experimental results showed that the citronellal, an important raw material for flavoring and perfumery industries, is the favorable product with a percentage as high as 86.9%, which is 7 times higher than that of catalyst by Ni-supported active carbon (Ni-AC).     

Cu/ZnO/Al_2O_3催化剂上1,4-丁二醇脱氢合成γ-丁内酯

研究了顺酐加氢催化剂Cu/ZnO/Al2 O3 在常压下对 1,4 丁二醇脱氢合成γ 丁内酯的催化活性 .结果表明 ,Cu/ZnO/Al2 O3 催化剂不但具有良好的顺酐加氢活性 ,而且在较温和的反应条件下对于 1,4 丁二醇脱氢同样具有良好的催化活性 ,γ 丁内酯的收率可达 95 %以上 .通过XRD和AES测试发现 ,Cu0 为催化剂的脱氢活性中心 ,ZnO的存在有利于Cu0 在载体表面的高度分散 ,并对脱氢活性有促进作用 ,在还原态的催化剂中ZnO被部分还原为ZnOx(x≤ 1) ,并与Cu0 形成Cu0 /ZnOx,构成最佳活性单元 .