Restructuring of 4H Phase Au Nanowires and its Catalytic Behavior toward CO Electro-oxidation

Au nanowires in 4H crystalline phase(4H Au NWs)are synthesized by colloid solution methods.The crys-talline phase and surface structure as well as its performance toward electrochemical oxidation of CO be-fore and after removing adsorbed oleylamine molecules(OAs)intro-duced from its synthesis are evaluat-ed by high-resolution transmission electron microscopy(HR-TEM),X-ray diffraction(XRD),underpoten-tial deposition of Pb(Pb-upd)and cyclic voltammetry.Different methods,i.e.acetic acid cleaning,electrochemical oxidation cleaning,and diethylamine replacement,have been tried to remove the adsorbed OAs.For all methods,upon the removal of the adsorbed OAs,the morphology of 4H gold nanoparticles is found to gradually change from nanowires to large dumbbell-shaped nanoparticles,accompanying with a transition from the 4H phase to the face-centered cubic phase.On the other hand,the Pb-upd results show that the sample sur-faces have almost the same facet composition before and after removal of the adsorbed OAs.After electrochemical cleaning with continuous potential scans up to 1.3 V,CO electro-oxida-tion activity of the 4H Au sample is significantly improved.The CO electro-oxidation activi-ty is compared with results on the three basel Au single crystalline surfaces reported in the lit-erature,possible origins for its enhancement are discussed.

在4H晶相Au纳米带上外延生长非常规晶相4H-Pd基合金纳米结构用于高效甲醇电催化氧化

Pd基合金纳米材料通常具有传统的面心立方(fcc)晶相。本文以密排六方4H相Au(4H-Au)纳米带为模板,外延生长非常规4H晶相的PdFe、PdIr和PdRu,形成4H-Au@PdM(M=Fe、Ir和Ru)核壳合金纳米带。合成的4H-Au@PdFe纳米带被用于碱性环境中甲醇电催化氧化反应(MOR)的催化剂,表现出优越的质量活性(3.69 A·mgPd^(−1)),分别为Pt/C和Pd黑催化剂质量活性的2.4和10.5倍,也跻身于最好的Pd基和Pt基MOR电催化剂之列。这一策略为合理设计和可控合成具有非常规晶相的多金属纳米结构提供了策略,从而为深入研究多金属纳米结构晶相依赖的性质和应用提供了可能。

功能化离子液体液相合成6-氨基-5-氰基-4-芳基-2-甲基-4H-吡喃-3-羧酸甲酯

报道了以离子液体1-(2-羟丙基)-3-甲基咪唑六氟磷酸盐为支撑试剂,β-酮酯和芳亚甲基丙二腈为原料,液相合成了11种6-氨基-5-氰基-4-芳基-2-甲基-4H-吡喃-3-羧酸甲酯化合物的新方法,产率83%～90%,纯度96%～99%。

Purification of Sulfuric and Hydriodic Acids Phases in the Iodine-sulfur Process

Iodine-sulfur （IS） thermochemical water-splitting cycle is the most promising massive hydrogen production process. To avoid the undesirable side reactions between hydriodic acid（HI） and sulfuric acid （H2SO4）, it is necessary to purify the two phases formed by the Bunsen reaction. The purification process could be achieved by reverse reaction of the Bunsen reaction. In this study, the purification of the H2SO4 and HI Phases was studied. The purification proceeded in both batches and the continuous mode, the influences of operational parameters, including the reaction temperature, the flow rate of nitrogen gas, and the composition of the raw material solutions, on the purification effect, were investigated. Results showed that the purification of the H2SO4 phase was dominantly-affected by the reaction temperature, and iodine ion in the sulfuric acid phase could be removed completely when the temperature was above 130℃; although, the purification effect of the HI phase improved with increasing of both the flow rate of nitrogen gas and temperature.

水相中一锅法合成新型4H-吡喃衍生物

以噻吩-2-甲醛、丙二腈和环己烷-1,3-二酮为原料,水为反应溶剂,在相转移催化剂的作用下,一锅法合成一系列新型4H-吡喃衍生物,通过NMR确定了该化合物结构。实验结果表明,新型4H-吡喃衍生物的产率为92%~98%;同时,确定了催化剂用量与原料物质的量最优比为0.6。此方法为新型4H-吡喃衍生物的提供了简介高效的合成方法以噻吩-2-甲醛、丙二腈和环己烷-1,3-二酮为原料,水为反应溶剂,在相转移催化剂的作用下,一锅法合成一系列新型4H-吡喃衍生物,通过NMR确定了该化合物结构。实验结果表明,新型4H-吡喃衍生物的产率为92%~98%;同时,确定了催化剂用量与原料物质的量最优比为0.6。此方法为新型4H-吡喃衍生物的提供了简介高效的合成方法。

水相中离子液体[ADPQ][BF_4]催化“一锅法”合成四氢苯并[b]吡喃

目的：制备1种以4-氨基奎宁为基础的离子液体,催化3组分一锅法制备四氢苯并吡喃的反应.方法：以水为溶剂,反应底物为芳香醛、活性亚甲基化合物和双甲酮.结果：最佳反应条件为：催化剂用量为芳香醛摩尔量的15%,反应温度为60℃,以水做溶剂.在此条件下,尝试的底物反应时间均在2 h内,收率为83%-96%.结论：该催化体系反应条件温和,时间短,收率高,反应后处理简单,催化剂重复使用4次催化效果变化不大.

一种四氢苯并吡喃及其衍生物的水相合成

制备了一种以三乙烯二胺(DABCO)为基础的离子液体;在水溶剂中,以该离子液体为催化剂催化三组分一锅法制备四氢苯并吡喃的反应,得到2-氨基-3-氰基-4-芳基-7,7-二甲基-5-氧代-4H-5,6,7,8-四氢苯并[b]吡喃;考察了反应时间、催化剂用量、催化剂加入时间、反应温度对反应收率的影响,确定了最优反应条件;由不同的芳香醛和活性亚甲基化合物制备了一系列四氢苯并吡喃衍生物,并讨论了可能的反应机理.结果表明,所选用的合成反应条件温和、时间短、收率高、后处理简单,且催化剂重复使用4次催化效果变化不大;就反应机理而言,所用催化剂具有双重催化活性.

固相法合成锂离子电池正极材料LiMn_2O_4

用 Li2 CO3和 Mn( OAc) 2 · 4 H2 O为锂锰源 ,添加少量柠檬酸或草酸在 5 5 0℃煅烧 4 h合成了尖晶石Li Mn2 O4。采用 X-射线衍射法 ,透射电镜和充放电测量研究了它们的结构和性质。用 Scherre公式计算样品粒度在 2 8.5 nm～ 4 0 .0 nm。添加草酸制备的样品充放电性能较好 ,首次充放电的放电容量可达 1 1 5 m

Single-and few-layer 2H-SnS_(2)and 4H-SnS_(2) nanosheets for high-performance photodetection

The properties of two-dimensional(2D)materials are highly dependent on their phase and thickness.Various phases exist in tin disulfide(SnS_(2)),resulting in promising electronic and optical properties.Hence,accurately identifying the phase and thickness of SnS_(2)nanosheets is prior to their optoelectronic applications.Herein,layered 2H-SnS_(2)and 4H-SnS_(2)crystals were grown by chemical vapor transportation and the crystalline phase of SnS_(2)was characterized by X-ray diffraction,ultralow frequency(ULF)Raman spectroscopy and high-resolution transmission electron microscope.As-grown crystals were mechanically exfoliated to single-and few-layer nanosheets,which were investigated by optical microscopy,atomic force microscopy and ULF Raman spectroscopy.Although the 2H-SnS_(2)and 4H-SnS_(2)nanosheets have similar optical contrast on SiO_(2)/Si substrates,their ULF Raman spectra obviously show different shear and breathing modes,which are highly dependent on their phases and thicknesses.Interestingly,the SnS_(2)nanosheets have shown phase-dependent electrical properties.The 4H-SnS_(2)nanosheet shows a current on/off ratio of 2.58×10^(5) and excellent photosensitivity,which are much higher than those of the 2H-SnS_(2)nanosheet.Our work not only offers an accurate method for identifying single-and few-layer SnS_(2)nanosheets with different phases,but also paves the way for the application of SnS_(2)nanosheets in highperformance optoelectronic devices.

微波辐射下水相中一锅法合成多芳基取代1,2-二氮杂衍生物

微波辐射下,以芳香醛和芳香酮为起始原料,由一锅法合成2,4,6-三芳基硫代吡喃盐,然后直接加入水合肼反应,几乎以定量收率仅只生成3,5,7-三芳基-4H-1,2-二氮杂衍生物。该法以水为反应溶剂且中间盐不用分离,具有操作简单、条件温和、产率高、环境友好等优点。产物经元素分析、1H NMR、MS表征了其结构。