纳米Pd/PEG600复合体系的结构形态与流变行为

采用超声辐射法,以氯化钯水溶液为前驱体,制备了纳米Pd/PEG600复合材料;利用高分辨透射电子显微镜并结合流变学方法,考察了纳米钯粒子对复合体系触变性的影响,并研究了纳米钯粒子的结构形态。结果表明,超声制备的纳米钯粒子呈椭球形、方形和球形,尺寸在5～10 nm,并且结晶度较好;复合体系的黏度和触变性均有所提高,这可能是纳米钯与PEG形成的特殊管状结构造成的。     

纳米Pd/P(AAEM-St)复合材料的制备与表征

超声引发乳液聚合制备了纳米钯/乙酰乙酸基甲基丙烯酸乙酯-苯乙烯共聚物[Pd/P(AAEM-St)]复合材料,研究了复合材料的结构及热稳定性。XRD结果表明Pd2+被还原成了Pd粒子,FTIR结果表明纳米粒子与聚合物基体之间存在相互作用,TG结果表明纳米粒子的存在对P(AAEM-St)基体的热稳定性有一定影响。     

DNA辅助合成Pd纳米粒子及其催化性能研究

采用鱼精DNA为模板,利用Pd2+离子与鱼精DNA间的配位作用将其预先结合在DNA模板上,再以原位还原的方法制备水相中稳定、分散的钯(Pd)纳米粒子。用透射电子显微镜(TEM)对Pd纳米粒子的形貌进行表征。以Pd纳米粒子催化4-硝基苯酚还原为4-氨基苯酚的实验来考察Pd纳米粒子的催化性能,实验结果发现鱼精DNA辅助合成的Pd纳米粒子有较好的催化性能。     

纳米Pd／PEG复合材料棒状结构的制备与表征

在超声辐射作用下,以不同相对分子质量的PEG为还原剂和稳定剂,合成了纳米Pd／PEG复合材料。XRD和UV—Vis结果证明了氯化钯被完全还原成钯,TEM显示PEG600呈长约0．5Ixm,直径为50～80nln的棒状结构,并将部分纳米钯粒子包覆在其中;XPS表明PEG030中的c-0H中Cls结合能（287．5eV）比标准的Cls结合能（2s6．5eV）降低了1．0eV,说明聚合物中羟基上的氧原子和纳米钯之间形成了一定的相互作用。     

金纳米粒子的特性、制备及应用研究进展

介绍了金纳米粒子的物理化学特性,归纳了金纳米粒子的制备方法,如传统的柠檬酸钠还原法、以两相或多相体系为基础的相转移法以及分两步合成的晶种法等,并对物理辅助制备方法如在制备过程中引入超声场、激光辐射等手段进行了简单的介绍。还对金纳米粒子的应用研究进展进行了综述。     

Pt修饰的Pd/石墨烯纳米复合材料的制备及对乙二醇氧化反应的电催化活性

以氧化石墨(GO)和Pd(NO₃)₂为原料,通过化学还原法制备Pd纳米粒子-石墨烯(Pd/G)纳米复合材料,然后以H₂PtCl₆作为Pt前体,在Pd纳米粒子的表面恒电位沉积Pt,制备不同Pt负载量的Pd/G(Pt-Pd/G)电极.利用场发射扫描电镜(FE-SEM)、透射电镜(TEM)和X射线能谱仪(EDX)对材料的微观结构进行了表征和分析.结果显示石墨烯上的金属粒子分散均匀,平均粒径约7.2nm.电化学测试结果显示Pt-Pd/G电极对乙二醇电化学氧化反应具有良好的催化性能.当纳米粒子的Pt:Pd原子百分比为1:42时,其反应峰电流密度分别为Pd/G和Pt/G电极的3.0倍和2.7倍.少量的Pt沉淀可显著改进Pd/G电极的催化活性.本研究采用的修饰方法简单,修饰效果明显,可应用于其他金属纳米复合材料的异金属修饰.     

离子液体稳定Pd纳米粒子催化脂肪酸甲酯加氢反应的研究

合成了对金属纳米粒子具有稳定特性的新型离子液体1-甲基聚氧乙烯醚-3-甲基咪唑氯盐(ILMPEG-750),将其作为稳定剂用于制备Pd纳米粒子催化体系。结果表明ILMPEG-750对Pd纳米粒子具有良好的稳定性,所得纳米粒子平均粒径为2.35nm,且分布均匀。将制得的纳米催化体系用于催化脂肪酸甲酯的加氢反应,在m(脂肪酸甲酯)=2.5g、w(Pd)=0.5%的催化体系10g、n(Pd)∶n(ILMPEG-750)=1∶5、溶剂m(甲苯)=5.0g、反应温度为210℃、反应时间为4h、氢气压力为6MPa的反应条件下,产物羟值为166mgKOH/g和碘值为13mgI2/100g。分离所得纳米催化体系不经处理重复使用6次后,所得产物的羟值和碘值分别为162mgKOH/g和8mgI2/100g。     

Pd负载电纺碳纳米纤维的制备及其催化活性

Pd纳米粒子负载的碳纳米纤维是催化Sonogahira偶合反应的良好催化剂,其高长径比使之易于从反应混合物中过滤分离;金属纳米粒子与碳纤维间的强相瓦作用使其具有良好的多次重复使用性.通过电纺丝技术和碳化技术制备了Pd金属纳米粒子负载的电纺碳纳米纤维,透射电镜观察显示最终碳化温度及在该温度下的停留时间是影响钯纳米粒子尺寸及其在纤维中分布的主要因素.并通过所得复合纳米纤维对Sonogahira偶合反应的催化活性研究,发现475～575℃这一温度范围是制备具有良好催化活性的金属钯纳米粒子负载的碳纳米纤维的最佳的碳化温度段.     

Co-Fe-Pd纳米粒子的可控制备及其氧还原催化性能

以Co(COOH)_2、FeCl_3和PdCl_2为原料,柠檬酸为稳定剂,乙醇为加速剂,采用超声辅助制备Co-Fe-Pd金属纳米粒子,并评估其氧还原反应(ORR)电催化性能。研究结果表明,Co-Fe-Pd金属纳米粒子平均粒径约3～5 nm,由于Co、Fe固溶于Pd晶格,使Co-Pd、Fe-Pd和Co-Fe-Pd纳米粒子仅显示Pd衍射峰,且伴有不同程度的宽化;相比于Co-Fe、Fe-Pd或Co-Pd纳米粒子,三元Co-Fe-Pd晶格压缩更为明显,晶格缺陷诱使的活性位点增加,氧还原催化能力增强;其氧还原起峰电位为1.03 V (vs RHE),Tafel斜率为-87 mV/dec,可与商用Pt/C催化剂相媲美;氧还原过程中电子转移数为3.80±0.04,说明其主导四电子转移路径;此外,RRDE结果显示氧还原过程中的中间产物H_2O_2含量约10%。     

柳树叶提取液还原制备水滑石负载纳米钯催化剂及催化Suzuki反应

以柳树树叶提取液作为还原剂和稳定剂,制备了水滑石负载纳米钯催化剂(Pd/HT)。采用IR、XRD、TEM、N-2吸附脱附等手段对制备的催化剂进行了表征,并研究了其催化Suzuki偶联反应的性能。表征结果显示:制备的Pd/HT中钯纳米粒子分散均匀,粒径分布较窄,平均粒径为3.8nm。提取液中的生物质不仅起到还原作用,而且还起到稳定钯纳米粒子的作用。催化Suzuki偶联反应结果表明:Pd/HT表现出优良的催化活性,重复使用5次,催化活性没有明显降低。     

腐生葡萄球菌合成纳米钯异位还原废水中Cr(Ⅵ)

利用腐生葡萄球菌(Staphylococcus saprophyticus.JJ-1)合成金属钯纳米颗粒,对其进行了表征;并利用"细菌/钯纳米颗粒"复合体系还原Cr(Ⅵ).结果表明,与其它检测的碳源相比,以甲酸钠为碳源还原钯盐,合成钯纳米颗粒的速度最快.在细胞干质量浓度为0.8g/L时,所合成的钯纳米颗粒催化还原Cr(...     

Enhanced Visible-Light Photocatalytic Degradation of Humic Acid by Palladium-Modified Nitrogen-Doped Titanium Oxide

Palladium-modified nitrogen-doped titanium oxide (TiON/PdO) nanoparticles were synthesized by a sol–gel process, for visible-light-induced photocatalysis using humic acid (HA) as a target. Our work shows that palladium modification has strong effects on the optical and photocatalytic properties of nitrogen-doped titanium oxide (TiON) photocatalysts. TiON/PdO nanoparticles demonstrated an enhanced photocatalytic activity over TiON within a narrow range of palladium concentration. Beyond this range, the adverse effect of palladium modification was observed in the visible-light-induced degradation of HA. The effects of palladium modification are discussed in terms of its role in controlling electron–hole recombination.     

Interaction between Pd and Cu nanoparticles in bimetallic CuPdx nanoparticles and its impact on oxidation of 1,2-propanediol to aliphatic acids

Bimetallic CuPd_x nanoparticles synthesized by the wet chemical reduction method were used as the catalysts in the catalytic oxidation of 1,2-propanediol with gaseous oxygen to aliphatic acids. The palladium and copper nanoparticles in the bimetallic CuP dxnanoparticles had an alloying trend. The catalytic activity of the palladium nanoparticles in the bimetallic CuP dxnanoparticles was enhanced by the interaction between the palladium and copper nanoparticles. When the bimetallic CuPd_7 nanoparticles catalyzed the oxidation of 1,2-propanediol in an alkaline aqueous solution at 100℃ for 3h, lactic, formic, and acetic acids were dominantly produced with the total selectivity of above 99% at the 1,2-propanediol conversion of 85.9%. The simulation of the reaction kinetic equation on the CuPd_7 catalyst showed that the reaction activation energy was 29.4kJ·mol~(-1), indicating that the bimetallic CuPd_7 nanoparticles had a high catalytic activity in the oxidation reaction between 1,2-propanediol and gaseous oxygen.     

纳米材料对环氧树脂耐热性的改性研究

采用纳米TiO2、Al2O3、SiO2,层状粘土有机蒙托土、海泡石和环氧树脂制备纳米复合材料,通过透射电镜研究纳米粒子在环氧树脂基体中的分散情况,采用差热分析测试不同纳米环氧树脂复合材料的玻璃化温度。结果表明,纳米粒子分散于基体中,可使环氧树脂的玻璃化温度提高。     

Hybrid films of polyimide containing in situ generated silver or palladium nanoparticles: Effect of the particle precursor and of the processing conditions on the morphology and the gas permeability

Hybrid organic/inorganic films have been prepared using different complexes soluble in a (BTDA/4,4′-ODA) poly(amic acid) solution. A silver based complex and two palladium based complexes were used and the metallic nanoparticles were formed by a single step process during the cure cycle applied to the film. Depending on the complex or the curing conditions used, either the nanoparticles formed were uniformly dispersed in the nanocomposite films, or the particles were also located at the film surface. The presence of the nanoparticles, whatever their composition, led to a decrease of the thermal degradation temperature in air atmosphere. The presence of 15 wt% of crystalline silver particles did not induce significant variation of the glass transition temperature and of the gas transport properties demonstrating low nanoparticle/matrix interactions. On the contrary, a pronounced effect in reducing the gas permeability for a wide variety of gases was observed for the nanocomposites containing the palladium based nanoparticles and this even for low palladium amount (5 wt%). Specific interactions between hydrogen and the Pd based nanoparticles were evidenced and the gas transport properties were discussed as a function of following parameters: the gas nature, the nanoparticle structure and composition, the developed morphology and the particle/matrix interactions.     

疏水性钯纳米团簇的合成及其作为表面增强拉曼散射基底的应用

以醋酸钯为前体、有机氢硅烷为还原剂开发了一种简单温和的疏水性钯纳米颗粒制备方法。通过调节前体、保护剂和还原剂的配比,在氯仿溶液中室温条件下合成了疏水性的钯纳米团簇和钯纳米球。运用透射电子显微镜（TEM）、X射线衍射（XRD）、光学接触角测试仪、循环伏安法（CV）、表面增强拉曼光谱（SERS）对这两种钯纳米材料进行了测试表征。TEM观察表明这两种钯纳米材料粒径分布均匀,分散性良好。接触角测试表明钯纳米团簇与钯纳米球均具有疏水性。CV测定结果显示这两种钯纳米材料具有良好的电催化稳定性,钯纳米团簇比钯纳米球对乙醇氧化具有更突出的电催化性能,表明钯纳米团簇结构稳定并具有更大的比表面积。SERS测试表明钯纳米团簇是一种优良的疏水性表面增强拉曼散射基底,利用这种基底对疏水性致癌物3,4-苯并芘和联苯胺进行了SERS快速检测,检测限为0.1mg/mL。     

溶剂稳定的钯金属纳米颗粒的制备与催化性能

用三缩四乙二醇作溶剂,制备了溶剂稳定的钯金属纳米颗粒,得到了分布均匀、粒径在2～3nm范国内的钯金属纳米颗粒。所得到的钯金属纳米颗粒用于环已烯的催化加氢反应,其催化活性较传统的钯／碳催化剂约高2倍。     

Biphasic Hydrogenation of Olefins by Functionalized Ionic Liquid‐Stabilized Palladium Nanoparticles

Palladium nanoparticles in the size range of 5–6 nm were prepared conveniently by reducing palladium(II) with atmospheric pressure hydrogen and stabilized by 2,2′‐dipyridylamine‐functionalized imidazolium cations according to our approach. The efficient catalytic conversion of cyclohexene into cyclohexane by the functionalized ionic liquid‐stabilized palladium nanoparticles has been performed under very mild hydrogen pressure (0.1 MPa) and at 35 °C. It was found that the concentration of palladium and the reaction temperature considerably affected the size and degree of aggregation of Pd nanoparticles in ionic liquid, which further changed the performance of the catalyst activity. The synthesized nanocatalysts can be recycled at least five times without any loss of the activity. Finally, the scope of substrates was also investigated. The excellent catalytic activity of the present system can be attributed to good stabilization and high dispersion of palladium nanoparticles.     

Sol–Gel Processing and Characterization of Pure and Metal-Doped SnO2 Thin Films

A chloride-based inorganic sol–gel route was used for preparing pure and metal (osmium, nickel, palladium, platinum)-doped SnO₂ sol. SnCl₄ was first reacted with propanol, then the resulting compound was hydrolyzed and subsequently mixed with solutions of the metal dopants. The obtained sols were used for depositing thin films by spin coating or for preparing powders by solvent evaporation at 110°C. FTIR spectroscopy and thermal analysis of the powders revealed that chlorine still bound to tin stabilized the sol against gelation by hindering the condensation reactions. Film characterizations showed that platinum and palladium, unlike nickel and osmium, were likely to form nanoparticles in the SnO₂ lattice. This result was discussed with regard to the different ways that platinum and palladium, on one hand, and nickel and osmium, on the other, modified the growth of SnO₂ grains and the film roughness and morphology. Dopants that formed nanoparticles (platinum, palladium) resulted in the roughest film, while dopants that did not form particles (nickel, osmium) resulted in SnO₂ grain size very close to that of pure SnO₂.     

Sulphonated “Click” Dendrimer‐Stabilized Palladium Nanoparticles as Highly Efficient Catalysts for Olefin Hydrogenation and Suzuki Coupling Reactions Under Ambient Conditions in Aqueous Media

Water‐soluble 1,2,3‐triazolyl dendrimers were synthesized by “click chemistry” and used to stabilize palladium nanoparticles (PdNPs). These new “click” dendrimer‐stabilized nanoparticles (DSN) are highly stable to air and moisture and are catalytically active for olefin hydrogenation and Suzuki coupling reaction, in aqueous media, under ambient conditions using a low amount of palladium (0.01 mol% Pd). Kinetic studies show high catalytic efficiency and high stability for the new “click” DSN in both reactions. The complexation of potassium tetrachloropalladate (K₂PdCl₄) to the triazole ligands present in the dendritic structures was monitored by UV/vis and, after reduction, the nanoparticles were characterized by transmission electron microscopy (TEM).