【作者】 郝世阳；

【导师】 王贵领；

【作者基本信息】 哈尔滨工程大学 ， 应用化学， 2011， 硕士

【摘要】 过氧化氢(H2O2)作为氧化剂的燃料电池具有结构简单、能量密度大、可在无氧条件下工作等很多优点,常用作水下电源和空间电源。目前过氧化氢基燃料电池阴极电还原的催化剂主要是贵金属,因其价格昂贵、资源稀缺而增加了燃料电池的成本。聚吡咯(ppy)类过渡金属催化剂,由于其特殊的结构和独特的性质,表现出良好的催化活性和稳定性,有望取代贵金属而成为阴极氧还原电催化剂,近年来成为学术界关注的焦点课题。通过一种无需热解的简单方法合成了一种钴-聚吡咯-碳(Co-ppy-C)复合材料,并使用X射线衍射分析(XRD)、透射电镜(TEM)、扫描电镜(SEM)等手段对其进行表征。XRD图谱表明所制备的材料中含有尖晶石构型的p-Co(OH)2。扫描电镜和透射电镜表征表明该催化剂的粒径大约为20-30 nm。以循环伏安法测试了Co-ppy-C电极在氢氧化钾(KOH)溶液和硫酸(H2S04)溶液中对H202电还原的催化性能,结果表明Co-ppy-C电极在3.0 mol·dm-3KOH溶液中具有非常高的催化活性和稳定性。当H202浓度为0.4mol·dm-3、电极电势为-0.4 V时,Co-ppy-C电极表面的电流密度达到了-45 mA·cm-2；而Co-ppy-C电极在酸性溶液中的催化性能较差,当H202浓度为0.4 mol·dm-3、电极电势为0.0 V时,Co-ppy-C电极表面的电流密度仅为-45 mA·cm-2。采用恒电流法制备导电聚吡咯修饰C0304纳米线电极,研究不同聚合时间和不同吡咯单体浓度对所制备的导电聚吡咯修饰C0304纳米线电极催化性能的影响,得出聚合时间为10 s,吡咯单体浓度为0.10 mol·dm-3时,催化效果最好。与未被修饰的Co304纳米线电极相比,聚吡咯修饰的C0304纳米线电极表现出更好的催化活性与稳定性。Co-ppy-C电极在3.0 mol·dm-3 KOH溶液中,当H202浓度为0.4 mol-dm-3、电极电势为-0.4 V时,Co-ppy-C电极表面的电流密度达到了-120 mA·cm-2,相比未被聚吡咯修饰的C0304电极大15 mA·cm-2。作为一种非铂催化剂,聚吡咯-过渡金属催化剂在催化活性与稳定性上都已显示出诱人的应用前景,通过进一步优化催化剂的成分与制备工艺,有望替代铂基催化剂,推动H202基燃料电池技术的产业化进程。更多还原

【Abstract】 The fuel cells using H2O2 as oxidant have simple structure, high energy density and can operaite without air. Therefore, the fuel cell using H2O2 as oxidant is good candidates of underwater and space power. Current cathode catalysts for Fuel cells using hydrogen peroxide as oxidant are noble metals, but they are so expensive and scarce that they will raise the costs of the fuel cells largely. Ppy-based transitional metal catalyst demonstrates excellent catalytic activity and durability with the special structure and characteristics, and is regarded as a kind of promising cathode catalyst, much attention has been paid to it in recent years.In this paper, we synthesized a cobalt-polypyrrole-carbon (Co-ppy-C) composite via a simple chemical method, without resorting to pyrolysis. It was characterized by X-diffraction spectroscopy (XRD)、transmission electron microscopy (TEM)、scanning electron microscopy (SEM). XRD pattern indicated that the structure of the Co-ppy-C includedβ-Co(OH)2. SEM and TEM characterization show that the Co-ppy-C nanoparticle with dimension of 20-30 nm. The performance for hydrogen peroxide electro-reduction in KOH solution and H2SO4 solution were investigated by cyclic voltammogram and chronoamperometry test. Results revealed that Co-ppy-C electrodes exhibit high activity and good stability for electrocatalytic reduction of H2O2 in 3.0 mol·dm-3 KOH solution. A current density of as high as-45 mA-cm-2 was achieved on the Co-ppy-C electrode when hydrogen peroxide concentration was 0.4 mol·dm-3 the potential was-0.4V; Co-ppy-C electrodes exhibit low activity in H2SO4 solution. A current density of as high as-45 mA-cm-2 was achieved on the Co-ppy-C electrode when hydrogen peroxide concentration was 0.4 mol·dm-3、the potential was 0.0 V.Constant current was adopted to obtain conducting polypyrrole chemically modified Co3O4 nanowires electrodes under same conditions. The polymerization time and dopant concentration were studied, it demonstrated that the polypyrrole modified Co3O4 nanowires electrodes were formed by 0.1 mol·dm-3 pyrrole for 10 s show better activity. Comparing to the Co3O4 nanowires electrode, these polypyrrole modified electrodes show better activity and greater stability. In 3.0 mol-dm-3 KOH solution, the polypyrrole modified Co3O4 nanowires electrode show the current density of-120 mA-cm-2, which is 15 mA-cm-2 higher than the Co3O4 nanowires electrodes without polypyrrole show.From above obtained results, it can be concluded that the Co-ppy-C and the polypyrrole modified Co3O4 nanowires catalyst have demonstrated a rather promising possibility to substitute commercialized platinum catalyst. It is belived that these achievements in this research has given a certain contribution to the development of the fuel cell using H2O2 as oxidant.更多还原