碳载Pt-P催化剂对氧还原的电催化性能

用NaH2PO2液相还原方法制得碳载Pt-P(Pt-P/C)催化剂(m(Pt)∶m(P)=5∶1)。 X射线衍射谱测量表明,Pt-P/C催化剂的Pt衍射峰的2θ值稍大于Pt/C催化剂的相应值,表明P进入了Pt晶格,形成了Pt-P合金。 电化学测试表明,Pt-P/C催化剂对氧还原的电催化性能要比商品化的E-TEK Pt/C催化剂好,其还原电位正移了40 mV。 由于Pt-P/C催化剂中Pt-P粒子的平均粒径和相对结晶度与Pt/C催化剂相似,推测Pt-P/C催化剂对氧还原的电催化性能好于Pt/C催化剂的原因可能为P的作用。     

5-氨基-6-硝基-[1,2,5]噁二唑并[3,4-b]吡啶-1-氧化物的新法合成

以2,6-二氯吡啶为起始原料,经肼基化、还原、硝化、Nietzki-Dietschy环合4步反应得到5-氨基-6-硝基-[1,2,5]噁二唑并[3,4-b]吡啶-1-氧化物.结合反应机理讨论了还原、硝化、Nietzki-Dietschy环合反应的影响因素,获得了合成-.氨基-6-硝基-[1,2,5]噁二唑并[3,4-b]吡啶-1-氧化物的最佳工艺条件,目标产物的总收率为59.2%.用1H NMR、MS和IR谱对5-氨基-6-硝基-[1,2,5]噁二唑并[3,4-b]吡啶-1-氧化物的结构进行了表征.     

以硼氢化钠为还原剂化学镀镍的电化学研究

采用线性电位扫描伏安法研究了以硼氢化钠为还原剂的化学镀镍体系, 考查了镀液组成及工艺条件对化学镀镍硼阴、阳极过程的影响, 结果表明: 乙酸镍和硼氢化钠含量的提高分别促进了Ni²⁺的还原反应和BH₄^-的氧化反应; 乙二胺、氢氧化钠以及添加剂硫脲、糖精钠对阴、阳极反应均有不同程度的抑制作用, 同时添加剂中的硫元素加速了镍的氧化; 升高温度有利于阴、阳极反应的进行.     

氧化铝负载Co基F-T合成催化剂还原性能

采用XRD、TPR、XPS和H2-TPD等技术对Co/Al2O3催化剂的还原性能进行了研究.还原温度低时,催化剂中Co物种还原不充分,活化不够,催化剂的F-T合成反应活性偏低;高温还原时,由于催化剂中金属钴颗粒聚集和增大使活性组分的有效活性面积减小,催化剂的F-T合成反应活性下降.还原温度在400～500℃之间存在最佳...     

手性铁催化体系在不对称催化中的应用研究

本文介绍了手性铁催化体系在酮及亚胺的不对称还原、烯烃及硫醚的不对称氧化、不对称环加成、不对称环丙烷化以及不对称Friedel-Crafts烷基化等反应中的应用.     

Ultrasonic‐assisted Synthesis of Fe Nanoparticles in the Presence of Poly(N‐vinyl‐2‐pyrrolidone)

Zero‐valent iron particles were prepared by wet reduction chemistry assisted with ultrasonic treatment. Such prepared particles have uniform size, exhibit crystalline structure and show strong paramagnetic property. Their surface modification by coating poly(N‐vinyl‐2‐pyrrolidone) (PVP) was investigated. The resulting Fe(0)‐PVP particles were monodispersed and possessed enhancing magnetization saturation. Those synthesis conditions to control the particle size and distribution were exploited.     

Magnetically Separable and Versatile Pd/Fe3O4 Catalyst for Efficient Suzuki Cross‐Coupling Reaction and Selective Hydrogenation of Nitroarenes

Magnetic nanoparticle‐supported Pd/Fe₃O₄ was readily prepared and proved to be versatile catalyst for efficient Suzuki cross‐coupling reaction, and the reduction of nitroarenes under mild conditions (balloon H₂ pressure and room temperature). The catalyst could be conveniently recovered and reused several times with sustained catalytic activity.     

锌-丙酸铵还原体系用于氢化偶氮苯的合成

选用锌粉和镁粉与不同饱和铵盐（草酸铵、丙酸铵和苯甲酸铵）水溶液组成还原体系,由偶氮苯制备氢化偶氮苯,根据反应时间及结果选取锌一饱和丙酸铵水溶液为最佳还原体系。在反应温度25℃时,研究了锌一饱和丙酸铵水溶液还原体系还原偶氮苯反应,考察了偶氮苯与锌粉物质的量比、饱和丙酸铵水溶液的用量对氢化偶氮苯收率的影响。实验结果表明：偶...     

Enhanced Electrocatalytic Performance of Anthraquinonemonosulfonate‐Doped Polypyrrole Composite: Electroanalysis for the Specific Roles of Anthraquinone Derivative and Polypyrrole Layer on Oxygen Reduction Reaction

To analyze the specific roles of anthraquinone‐2‐sulfonate (AQS) and polypyrrole (PPy) layer on oxygen reduction reaction (ORR), the electrocatalytic reduction of oxygen was investigated on the AQS/PPy composite modified graphite electrode. Results show that the enhanced electrocatalytic performance is attributed to the excellent electrocatalytic activity of the immobilized AQS functional groups to mediate two‐electron reduction of O₂ to H₂O₂. The PPy layer may not participate in ORR, but it can further catalyze the two‐electron reduction of H₂O₂ to produce H₂O in the potential range more negative than that the two‐electron reduction of oxygen proceeds efficiently on the AQS sites.     

Large deviation theory for a homogenized and “corrected” elliptic ODE

We study a one-dimensional elliptic problem with highly oscillatory random diffusion coefficient. We derive a homogenized solution and a so-called Gaussian corrector. We also prove a “pointwise” large deviation principle (LDP) for the full solution and approximate this LDP with a more tractable form. Applications to uncertainty quantification are considered.