纳米结构Pt基合金催化剂的设计、制备与电催化性能研究

发布时间：2018-03-10 04:17

本文选题：机械合金化　切入点：脱合金化　出处：《山东大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文中,我们采用机械合金化方法获得多种成分配比的A1基前驱体含Pt合金,结合脱合金化处理(使用NaOH, HNO3溶液)方法,制备了多种纳米多孔Pt基合金电催化剂。所制备的合金催化剂通过X射线衍射,扫描电子显微镜,透射电子显微镜和高分辨透射电子显微镜进行表征,同时对所得Pt基合金电催化剂进行了燃料电池阳极甲醇氧化和阴极氧气还原反应的电化学催化反应实验。将过渡族金属元素与贵金属铂(Pt)合金化是提高燃料电池催化剂材料的重要措施,因而十分有必要对其进行研究探讨。在本实验中,首先通过机械合金化制备A166Cu30Pt3Ti1,Al66Cu30Pt2TI2和Al66Cu30Pt1Ti3四元前驱体合金。对前驱体合金进行两步脱合金化处理,通过X射线衍射、扫描／透射电镜等分析发现获得了具有三维双连续结构的纳米多孔二元PtCu和三元PtCuTi合金。电化学测试表明,不同组分的纳米多孔Pt基二元、三元合金具有不同的甲醇催化质量／面积活性且均优于商用PtC催化剂。另外,Ti的加入使三元合金PtCuTi的抗CO中毒性能显著提高。通过类似的方法将机械合金化制备的Al80Cu6Ni6Co6Pd1Pt1前驱体合金经过两步脱合金处理制备纳米多孔PtPdAlCu合金。X射线衍射结合二元平衡相图分析,可以发现机械合金化制备的Al80Cu6Ni6Co6Pd1Pt1前驱体合金由单一的Al4Cu9相组成。进行脱合金处理后的X射线衍射图像表明,非贵金属元素(Cu,Al等)溶入Pt面心立方结构中形成了固溶体,通过扫描电子显微镜和透射电子显微镜分析发现得到了直径约1μ m的合金纳米颗粒,颗粒内部具有开放、双连续且交互的孔洞／韧带结构。元素分布分析发现每种元素分布均匀,没有纳米颗粒团聚现象。进一步的电化学测试表明,纳米多孔PtPdAlCu合金不仅具有比商用PtC催化剂更好的阳极甲醇催化和抗CO中毒性能,还具有优异的阴极氧还原性能,包括较高的质量／面积催化活性。将机械合金化得到的Al66Cu30(Pt44Ru41Os10Ir5)4前驱体合金经过一步脱合金处理得到PtRuCuOsIr多元合金。脱合金处理后的X射线衍射表明,Ru, Cu, Os, Ir元素溶入Pt面心立方结构中形成了固溶体合金,通过扫描电子显微镜和透射电子显微镜分析发现得到了三维双连续的孔洞／韧带(2.5nm)结构。相应的电化学测试表明,纳米多孔多元PtRuCuOsIr合金具有比商用PtC催化剂更好的甲醇催化、抗CO中毒性能和优异的氧还原质量／面积催化活性,更表现出持久的氧还原稳定性。我们认为,不同合金元素的添加对于Pt电子结构改变不同,合金中Pt原子电子结构的改变对于催化性能有着重要的影响作用,因此不同程度的改变了Pt基合金催化剂的电催化性能。同时,三维的多孔结构以及相互联通的韧带结构为物质和电子传输提供了良好的通道,加速了反应的动力学过程。
[Abstract]:In this paper, we use mechanical alloying method to obtain Al base precursor containing Pt alloy with various compositions, and combine with dealloying (NaOH, HNO3 solution) method. A variety of nano-porous Pt based alloy electrocatalysts were prepared and characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and high-resolution transmission electron microscope. At the same time, the electrochemical catalytic reaction experiments were carried out for the anodic methanol oxidation and cathodic oxygen reduction of the Pt based electrocatalysts. Alloying the transition metal elements with the precious metal platinum (Pt) was used to improve the fuel cell performance. Important measures for catalyst materials, In this experiment, A166Cu30Pt3Ti1A66Cu30Pt2TI2 and Al66Cu30Pt1Ti3 quaternary precursor alloys were prepared by mechanical alloying. Scanning / transmission electron microscopy (TEM) analysis showed that nano-porous binary PtCu and ternary PtCuTi alloys with three-dimensional double-continuous structure were obtained. The ternary alloy has different methanol catalytic mass / area activity and is superior to commercial PtC catalyst. In addition, the addition of Ti can improve the CO toxicity of ternary alloy PtCuTi. The mechanical alloying method is used to prepare the ternary alloy. Nano-porous PtPdAlCu alloy prepared by two-step dealloying of Al80Cu6Ni6Co6Pd1Pt1 precursor alloy. X-ray diffraction and binary equilibrium phase diagram analysis. It can be found that the Al80Cu6Ni6Co6Pd1Pt1 precursor alloy prepared by mechanical alloying is composed of a single Al4Cu9 phase. The X-ray diffraction images after dealloying show that the non-noble metal element (Cu-Al) is dissolved into the Pt face-centered cubic structure to form a solid solution. The results of scanning electron microscopy and transmission electron microscopy show that the alloy nanoparticles with a diameter of about 1 渭 m have an open interior. Double continuous and interactive pore / ligament structure. Element distribution analysis shows that each element is uniformly distributed, and no nanoparticles agglomeration. Further electrochemical tests show that, The nano-porous PtPdAlCu alloy not only has better catalytic performance of anodic methanol and anti-CO poisoning than commercial PtC catalyst, but also has excellent cathodic oxygen reduction performance. The Al66Cu30(Pt44Ru41Os10Ir5)4 precursor alloy obtained by mechanical alloying was treated by one step dealloying to obtain PtRuCuOsIr multicomponent alloy. The X-ray diffraction after dealloying showed that Ruu, Cu, Os, ir elements were dissolved into Pt. A solid solution alloy is formed in the face-centered cubic structure. By scanning electron microscope and transmission electron microscope analysis, the three-dimensional double-continuous pore / ligamentum 2.5 nm structure was obtained. The electrochemical measurements showed that the nano-porous multicomponent PtRuCuOsIr alloy had better methanol catalysis than commercial PtC catalyst. The resistance to CO poisoning and the excellent mass / area catalytic activity of oxygen reduction show the stability of oxygen reduction. We think that the addition of different alloy elements has different changes in the electronic structure of Pt. The changes of the electronic structure of Pt atoms in the alloy have an important effect on the catalytic performance, so the electrocatalytic properties of the Pt based alloy catalysts are changed in varying degrees. The three-dimensional porous structure and the interconnected ligament structure provide a good channel for the transport of matter and electron, and accelerate the kinetic process of the reaction.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TM911.4

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