【作者】 齐悦；

【导师】 张辉； 杨德仁；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2014， 博士

【摘要】 新型金属与金属氧化物复合纳米材料作为锂离子电池负极材料与燃料电池催化剂具有独特的结构优势,因而表现出了优越的电化学性能,被认为是新一代动力电池电极材料的理想选择。本论文提出了多种制备手段,包括湿化学法、化学气相沉积法、射频溅射法、电化学沉积法以及水热法等,合成了一系列金属和过渡金属氧化物的新型复合纳米材料,包括Co2SnO4@C复合纳米颗粒、Zn2Sn04@C复合纳米棒、Co3O4@SnO2@C复合纳米棒、CoO-Cu复合纳米棒阵列、CoO-NiSi复合纳米线阵列、CoO-graphene复合纳米片、Pt-Cu/C合金纳米晶、Rh-Pd/C合金纳米晶以及Pd-Cu/C合金纳米颗粒。由于上述复合纳米材料独特的结构与形貌特征,它们都表现出了优异的电化学性能,总结全文的工作,取得了以下主要创新结果：(1)采用简便的两步水热法合成了Co2SnO4@C复合纳米颗粒以及Zn2Sn04@C复合纳米棒并将其应用于锂离子电池负极材料中。由于碳层的体积缓冲效应与较高的电导率,包碳后的Co2SnO4@C复合纳米颗粒以及Zn2Sn04@C复合纳米棒负极材料与未包碳的纳米材料相比其循环性能有了较大的改善。(2)采用层层包覆的思想,通过水热反应结合后续的热处理合成了Co3O4@SnO2@C复合纳米棒并将其应用于锂离子电池负极材料中。由于碳层的体积缓冲效应与较高的电导率,包碳后的Co3O4@SnO2@C复合纳米棒负极材料与未包碳的纳米棒相比其循环性能有了较大的改善。(3)采用化学气相沉积与射频溅射的方法合成了CoO-Cu复合纳米棒以及CoO-NiSi复合纳米线阵列电极并将其应用于锂离子电池负极材料中。由于其独特的一维阵列化结构导致的充足的体积缓冲空间与较高的电导率,上述复合纳米阵列电极与平板电极相比其大电流下循环性能有了极大的改善。(4)采用油胺中原位生长的方法合成了高负载率的CoO-graphene复合纳米材料并将其应用于锂离子电池负极材料中。由于石墨烯复合结构的体积缓冲效应与极高的电导率,制备的CoO-graphene(9：1)复合纳米材料表现出优异的循环性能与极高的质量比容量,同时在大电流下电池的快速充放电性能也获得了较大的提高。(5)采用油胺共还原法合成了一系列不同组分的Rh-Pd合金纳米枝晶以及Pt-Cu合金纳米晶并将其作为催化剂应用于甲醇氧化与氧还原反应中。我们发现还原速率以及表面活性剂对于特定形貌纳米晶的成功合成起到至关重要的作用。由于它们独特的具有高指数晶面的微观结构以及双金属间的协同作用,上述合金纳米晶表现出优于商用铂碳催化剂的催化活性与稳定性。(6)采用油胺中共还原法合成了一系列不同尺寸的Pd-Cu合金纳米颗粒并将其制成了Pd-Cu/C催化剂。我们发现通过控制反应中加入十六烷基三甲基溴化铵(CTAB)的量能够实现对Pd-Cu产物尺寸的调控。我们同时还发现三辛基氧磷(TOPO)作为络合剂对于单分散合金纳米颗粒的成功合成起到至关重要的作用。由于其均匀的合金结构与较大的比表面积,Pd-Cu/C催化剂期望能在甲酸氧化反应中表现出良好的催化性能。更多还原

【Abstract】 Due to the unique nano-structural properties, novel metal and metal oxide hybrid nanomaterials as anodes for lithium-ion batteries and catalysts for fuel cells are expected to exhibit excellent electrochemical performance, and therefore have been considered to be one of the most promising candidates as the electrode materials for the next generation of power batteries.In this dissertation, we propose various synthetic methods to obtain a rich variety of novel metal and metal oxide hybrid nanomaterials, including hydrothermal method, chemical vapor deposition (CVD), RF-sputtering, electrochemical deposition, and wet chemical method. By using hydrothermal method and subsequent calcination, Co2SnO4@C core-shell nanoparticles, Zn2SnO4@C core-shell nanorods, and Co3O4@SnO2@C core-shell nanorods have been prepared. By using electrochemical deposition and RF-sputtering methods, CoO-Cu nanorod arrays and CoO-NiSi nanowire arrays have been fabricated. In addition, CoO-graphene nanosheets, Pt-Cu/C alloy nanocrystals, Rh-Pd/C alloy nanodendrites, and Pd-Cu/C alloy nanoparticles have also been generated by using wet chemical method. Owing to their unique nano-structural properties, the above-mentioned hybrid nanomaterials exhibit excellent electrochemical performance. The main innovative results are displayed as follows:(1) Co2SnO4@C core-shell nanostructures and Zn2SnO4@C core-shell nanorods have been synthesized through a simple glucose hydrothermal and subsequent carbonization approach. These core-shell nanostructures remarkably improved the cyclic performance compared to pure Co2SnO4and Zn2SnO4nanocrystals, which can be attributed to the uniform and continuous carbon buffering matrix.(2) Co3O4@SnO2@C core-shell nanorods have been fabricated through a facile hydrothermal and subsequent carbonization approaches. These core-shell nanorods exhibited good cycling and enhanced power rate performances, which can be ascribed to the synergetic effect between CO3O4and SnO2, as well as the structural stability and improved electronic conductivity of the carbon matrix.(3) Nanostructured hybrid CoO/Cu and CoO/NiSiX core-shell nanowire array electrodes have been synthesized through chemical deposition and RF-sputtering. When applied as the anode material for lithium-ion batteries, the electrochemical performance of the nanostructured hybrid electrode is much better than planar electrode, which can be attributed to the large accessible surface area and improved electronic/ionic conductivity of the nanostructured electrodes.(4) Highly loaded CoO/graphene nanocomposites have been synthesized through a thermal decomposition process in a mixture containing Co(acac)3and graphene with oleylamine (OAm) as both solvent and reducing agent. The as-prepared highly loaded CoO/graphene nanocomposites were evaluated as anodes for lithium-ion batteries, which exhibited superior electrochemical performances including large reversible capacity, excellent cyclic performance, and high rate capability. We believed that the robust composite structures, large quantity of accessible active sites, and synergistic effects between CoO NCs and graphene may be responsible for the significantly enhanced performance.(5) Pt-Cu alloy concave nanocubes and Rh-Pd alloy nanodendrites with high-index facets in high qualities and yields have been synthesized through a facile oil-phase method under kinetic control. When supported on carbon, the alloy nanocrystals showed enhanced electrocatalytic activity and durability for methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) relative to the commercial Pt/C due to a combination of composition and facet effects.(6) CuPd alloy nanoparticles with average sizes varying from6-23nm have been synthesized by the coreduction of Pd(acac)2and Cu(acac)2with OAm as both the solvent and reductant and TOPO as a stabilizer. The amounts of CTAB in the reaction solution were a key to the successful size-control of alloy nanoparticles. In addition, TOPO played a key role in controlling nucleation and growth of Cu and Pd into CuPd alloy nanoparticles. These alloy nanoparticles are expected to exhibit the good performance as catalysts for formic acid oxidation.更多还原