【作者】 李翔；

【导师】 陈卫祥；

【作者基本信息】 浙江大学 ， 化学， 2006， 硕士

【摘要】 燃料电池是绿色、高效的新型发电装置,其中直接甲醇燃料电池(DMFC)是以便于储存和运输的甲醇作为燃料,具有较高的能量转化效率,被认为是十分理想的可移动或者小型化能源之一,在交通、通讯、军事、航天等方面具有广阔的应用前景和巨大的潜在市场,是目前研究最为广泛的一种燃料电池。但是DMFC研究中有两个问题急需解决:一是低温下甲醇在阳极上的电催化氧化活性不高;二是甲醇从阳极透过电解质膜渗透到阴极严重,这就需要制备对甲醇氧化的电催化活性高的催化剂。过渡金属Pt以及Pt基合金材料是有机分子脱氢氧化催化剂的首选材料,因此是常用的此类燃料电池的阳极催化剂。催化剂的活性与其颗粒大小、分布、形貌等因素有关,所以制备粒径适宜、粒径分布均匀的催化剂是提高催化剂的催化活性的关键。 本论文主要研究了用多元醇方法制备高分散的碳负载Pt、PtRu、PtNi金属纳米粒子,用XRD、TEM等研究手段对其结构进行表征,并用电化学分析方法研究了其对甲醇氧化的电催化活性。 通过微波-多元醇方法制备了Pt/CNTs催化剂,并用KOH调节反应前驱体溶液的pH值。通过XRD、TEM对其结构进行分析,结果表明制备的Pt/CNTs催化剂的金属纳米粒子粒径随着反应前驱体溶液pH值的逐渐增大而逐渐减小,说明pH值对多元醇方法制备金属纳米粒子的粒径大小具有一定的调控作用,而且该调控方法可控性好、操作简单。通过电化学研究方法(循环伏安曲线、极化曲线)研究了Pt/CNTs催化剂对甲醇氧化的电催化性能,结果表明Pt/CNTs催化剂对甲醇的电化学氧化具有较高的催化性能,并且当反应前驱体溶液pH=7.4左右时,制备的Pt/CNTs催化剂的电催化性能最高,并且对CO的抑制较为稳定。 通过多元醇方法,并添加醋酸钠作为稳定剂,制备了具有不同Pt-Ru原子比例的碳负载PtRu合金催化剂(PtRu/XC-72)。对其结构进行分析,结果表明制备的PtRu/XC-72催化剂的PtRu合金粒子较小,而且粒径分布均匀;并通过对甲醇更多还原

【Abstract】 Fuel cells are a kind of green power source with high efficiency, one of which is direct methanol fuel cell (DMFC). DMFC is believed to be an ideal small and mobile energy sources, it will be widely used in fields of traffic, communication, military affairs and aviation etc. There are two major problems about DMFC, one of which is that the electrocatalytic activity of methanol at anode is low, the other is that the penetration of methanol from anode to cathode is quite severe. Therefore it is a urgent need to prepare a kind of anode catalyst with high electrocatalytic activity for methanol oxidation. Transition metal Pt and its alloys are the common oxidation catalysts for organic molecules including methanol for the dehydrogenation reaction, therefore they are good anode catalysts of DMFC. The catalytic activity of the catalysts will be influenced by the size, distribution and shape of the particles, therefore it is very important to prepare catalysts with small size and homogeneous size distribution.This dissertation is mainly about the research of the Pt, PtRu, PtNi nanoparticles highly dispersed on carbon supports which are prepared by polyol process. Such analytic instruments as XRD, TEM were used to characterize the structure of the prepared Pt, PtRu, PtNi nanoparticles, whose electrocatalytic activities for methanol oxidation are analyzed by electrochemical tests.We synthesized Pt/CNTs catalysts using microwave-polyol process, by adding KOH to adjust the initial pH of reaction solution. The structures of the samples were characterized by XRD and TEM, the results indicated that the particle size of synthesized Pt nanoparticles can be controlled by the pH of reaction solution, and this controlling method was efficient and simplified. The electrochemical tests proved that the Pt/CNTs catalysts possess high electrocatalytic activity for methanol oxidation, and the results indicated that the Pt/CNTs catalysts prepared under the pH of 7.4 had ahigher electrocatalytic activity than other samples.In ethylene glycol solution, we synthesized PtRu/XC-72 catalysts with different proportion of Pt-Ru atoms by using sodium acetate as stabilizer. Such analytic instruments as XRD, TEM were used to characterize the structure of samples and the results indicated that the prepared PtRu particles had small size and homogeneous size distribution. The electrochemical tests proved that PtRu/XC-72 catalysts had high electrocatalytic activity for methanol oxidation, and they could effectively restrain CO. The results of electrochemical tests about three PtRu/XC-72 catalysts with different proportion of Pt-Ru atoms indicated that the catalyst with Pt-Ru proportion about 1:1 had better electrocatalytic activity than other samples.In ethylene glycol solution, we synthesized PtNi/XC-72 catalysts using sodium acetate as stabilizer. The results of characterization indicated that the prepared PtNi/XC-72 catalysts had small particles size and homogeneous size distribution. The electrochemical tests proved that the PtNi/XC-72 had better electrocatalytic activity for methanol oxidation and more effectively restraining effect to CO than Pt/C catalysts. And it could also be proved that the PtNi/XC-72 catalysts worked more steadily than PtRu/XC-72 catalysts when operating for long time.更多还原