离子液体中水热合成Pt-Pd/MWCNTs和Pd/MWCNTs催化剂

采用水热合成法, 以离子液体1-乙基-3-甲基咪唑四氟硼酸盐(C₆H₁₁BF₄N₂, EMIBF₄)为溶剂制备了Pt-Pd/MWCNTs(Multi-walled carbon nanotubes)和Pd/MWCNTs催化剂. X射线衍射(XRD)和X射线能量散射谱(EDS)测试证明了Pt-Pd合金和Pd纳米颗粒在MWCNTs的表面生成. 透射电子显微镜(TEM)照片不仅证明了在MWCNTs表面Pt-Pd, Pd纳米颗粒的生成, 而且还表明样品颗粒的平均粒径约为4 nm. 循环伏安(CV)和交流阻抗(EIS)测试表明, 在碱性环境下, 乙醇在Pt-Pd/MWCNTs和Pd/MWCNTs修饰的玻碳(GC)电极上均能发生氧化反应, 与Pd/MWCNTs修饰的电极相比, 在Pt-Pd/MWCNTs上乙醇的起峰电位负移了大约200 mV, 且具有更高的氧化峰电流值.     

Electroless Deposition of Nickel Nanowire and Nanotube Arrays as Supports for Pt-Pd Catalyst for Ethanol Electrooxidation

Nickel nanowire and nanotube arrays as supports for Pt-Pd catalyst were prepared by electroless deposition with anodic aluminum oxide template. Pt-Pd composite catalyst was deposited on the arrays by displacement reaction. SEM images show that the nickel nanowires have an average diameter of 100 nm and the nickel nanotubes have an average inner diameter of 200 nm. EDS scanning reveals that elemental Pt and Pd disperse uniformly on the arrays. Cyclic voltammetry study indicates that the nickel nanotube array loaded with Pt-Pd possesses a higher electrochemical activity for ethanol oxidation than the nickel nanowire array with Pt-Pd.     

X-ray diffraction evidence of the single solid solution character of bi-metallic Pt-Pd catalyst particles on an amorphous SiO2 substrate

An X-ray diffraction study was carried out on powders of a series of catalysts prepared from aqueous solutions of H₂PtCl₆ and PdCl₄ and amorphous SiO₂ with different concentrations in weight of Pt and Pd at about 4% in overall metallic weight. Measurements of the position of high angle Bragg reflections in the diffractograms show evidence of the fact that the small catalyst particles are bi-metallic Pt-Pd crystals having a face-centred cubic Bravais lattice. The lattice constant of these crystals was found to change with the relative concentration of Pt and Pd by following the Vegard’s rule. This correlation leads to the conclusion that the bi-metallic catalyst particles are made of a single solid solution of Pt and Pd atoms in the whole range of relative concentrations. Relative concentrations of these metals in the samples under study were determined by using energy dispersive X-ray spectrometry and their values were found to be close to the stochiometric relative concentrations in weight of the metals in the precursor aqueous solution. An average size of about 96 Å was estimated for the bi-metallic particles from the full-width at half-maximum value measured for the (2 0 0) diffractometric curve.     

石墨烯纳米片担载Pt-Pd双金属纳米球作为甲醇氧化的电催化剂(英文)

利用简便的无表面活性剂的方法合成了石墨烯担载的Pt-Pd双金属纳米球.首先由Na2PdCl4与氧化石墨烯发生氧化还原反应生成Pd晶种,然后诱导Pt纳米粒子的生长,得到Pt-Pd双金属纳米球.采用扫描电子显微镜、透射电子显微镜和X射线粉末衍射仪表征了合成的Pt-Pd/GR催化剂的结构,并测定了其作为甲醇氧化电催化剂的性能.结果表明,Pt-Pd/GR催化剂对甲醇氧化反应表现出高催化活性和稳定性,甲醇氧化电流密度为51.8mA·cm-2.     

化学镀制备镍纳米线/管阵列铂钯催化剂载体

以阳极氧化铝作为模板,用化学镀的方法制备了可以用作铂钯复合催化剂载体的镍纳米线和纳米管阵列,利用置换反应将铂钯复合催化剂沉积在镍纳米阵列材料上．SEM图片表明镍纳米线的平均直径 为100 nm,镍纳米管的平均内径为20 nm． EDS扫描的结果表明铂钯元素均匀地分布在阵列材料上．循环伏安研究发现载有铂钯催化剂的镍纳米管阵列对乙醇氧化的电催化活性明显高于载有铂钯催化剂的镍纳米线阵列．     

常温常湿条件下CO氧化铂-钯催化剂制备的研究

采用浸渍法制备负载型铂-钯催化剂,比较详尽的考察了制备条件对其催化CO氧化活性的影响.结果表明:常温浸渍、陈化时间大于5 h、H2还原制得的催化剂,具有很好的低温活性和抗湿性.在相对湿度大于90%和空气中含100 ppm CO的条件下,Pt、Pd含量均为0.3%的催化剂在1 h内对CO的常温消除效率高于90%.     

One-step synthesis of Pt-Pd catalyst nanoparticles supported on few-layer graphene for methanol oxidation

In this study, Pt-Pd nanoparticles (NPs) supported on few-layer graphene (FLG) have been firstly prepared by one-step arc discharge evaporation of carbon electrodes containing both Pt and Pd elements. The few-layer graphene and Pt-Pd nanoparticles were achieved simultaneously through the evaporation process. After a high-temperature hydrogen treatment, the Pt-Pd/graphene was applied in the study of methanol oxidation in direct methanol fuel cell. The total weight of electrocatalyst keeps 2 wt% of the electrode. The sample with a mass ratio of Pt:Pd = 3:1 (H-Pt₃Pd₁/G) exhibits better electrocatalytic activity (198 mA mg-1 pt) and better tolerance to carbon monoxide(CO) poisoning (I_f/I_b = 1.26). It is noteworthy that the value of I_f/I_b can reach to 1.55 for the sample with the mass ratio of Pt:Pd = 2:1 (H-Pt₂Pd₁/G),which implies its excellent ability of CO tolerance. The introduction of Pd element may open a new strategy to improve the CO tolerance by arc discharge evaporation.     

柴油尾气DOC催化剂Pt-Pd/CeO2的活性和抗硫性

采用浸渍法制备了不同Pt、Pd比例的Pt-Pd/CeO₂催化剂,考察了其催化氧化模拟柴油车尾气的活性,并测试了抗硫性。活性测试结果表明,Pt、Pd协同降低了催化剂的起燃温度,其比例对催化剂性能影响很大,其中,Pt_0.2Pd_0.8/CeO₂催化剂在模拟柴油车尾气(丙烯(C₃H₆)、一氧化碳(CO)和一氧化氮(NO))中的催化活性最高;C₃H₆的t₅₀降到170℃,CO的t₅₀降到了150℃,显示了良好的Pt、Pd协同效应;H₂-TPR表征和抗硫性结果分析表明,高比例Pt/Pd催化剂具有更多的表面活性氧,其相对数值与催化剂抗硫性能的关联度高,在催化剂硫酸盐中毒的条件下,更有利于催化反应的进行。