【作者】 陈秀；

【导师】 何建平；

【作者基本信息】 南京航空航天大学 ， 应用化学， 2009， 硕士

【摘要】 以可溶性酚醛树脂为碳源、F127为模板剂,通过溶剂诱导自组装法制备的有序介孔碳亲水性较差,化学还原法负载Pt催化剂的性能比硬模板法制备的有序介孔碳负载Pt催化剂的性能差。为此,本文尝试对有序介孔碳表面进行改性。为了进一步降低Pt的负载使用量,提高其使用效率,本文还制备了核壳结构M@Pt(M=Co, Ni)催化剂,以提高Pt的催化活性。对有序介孔碳表面修饰的常用方法是在其表面引入合适的官能团。本文利用苯胺单体在有序介孔碳上原位聚合得到有序介孔碳-聚苯胺复合材料,并于300℃~900℃下进行煅烧。研究结果表明,聚合后的高温煅烧对介孔碳有序结构几乎没有影响,且能在碳表面留下亲水性能较好的的亚胺基团。以其为载体,微波法负载Pt催化剂后电化学活性面积可达59.4m2g-1,比纯有序介孔碳负载Pt催化剂(2.4m2g-1)的活性高。显示了亚胺基团表面修饰能有效的提高有序介孔碳负载Pt催化剂的性能。本文还尝试在制备有序介孔碳的过程中采用乙酸钴作为辅助催化剂。实验结果表明,适量钴盐的加入对介孔碳的有序结构几乎没有影响,且由于所加入Co元素在高温下的还原,使Pt的负载有了较好的活性点,更利于Pt的还原沉积,从而可使Pt催化剂的电化学活性面积达到128.7m2g-1。表明了在合成介孔碳的过程中添加适量的钴盐也能够有效改善碳负载Pt催化剂的性能。为进一步降低Pt的负载使用量,改善其催化性能,本文还从Pt催化剂结构出发,利用二次微波法和置换法分别制得Co@Pt/XC-72和Ni@Pt/XC-72核壳结构催化剂。形成核壳结构能提高Pt的利用率和比表面积。循环伏安测试表明,Co@Pt/XC-72和Ni@Pt/XC-72催化剂的电化学活性面积分别为84.3m2g-1和100.1m2g-1,均高于纯Pt催化剂。综上所述,对有序介孔碳表面进行官能团改性或者在合成过程中添加适量的金属盐均能有效的提高碳负载Pt催化剂的性能,与形成M@Pt核壳结构催化剂以降低Pt的负载使用量相比,均能达到提高Pt催化剂使用效率的目的,在质子交换膜燃料电池催化剂方面有广阔的应用前景。更多还原

【Abstract】 Ordered mesoporous carbon has been synthesized from a solvent inducement self-assembly with resol as carbon precursor, F127 as the structure directing agent in this paper. It has been proved that the obtained carbon was hydrophobic, it represents worse performance than hard-templet carbon when supported Pt catalyst with chemical reduction method. So it is necessary to modify the surface of ordered mesoporous carbon in order to improve its wettability. In order to reduce the quantity and improve the use ratio of Pt, M@Pt(M=Co, Ni) core-shell structure catalyst was prepared in this paper.Introducing the functional group to the surface of ordered mesoporous carbon is a frequently-used method. Nitrogen-doped ordered mesoporous carbon was synthesized by carbonizing at 300℃~900℃, containing polymerized aniline onto ordered mesoporous carbon. The research revealed that the nitrogen-doped carbon, which was carbonized at high temperature, not only had ordered mesoporous structure, but also reserved many hydrophilic imine groups. It represented better electric-catalysis performance than pure carbon when loaded Pt particles with a microwave synthesis process. Its active surface area is 59.4m2g-1, which was higher than pure carbon loaded Pt catalyst(2.4m2g-1). It indicated that imine group modified ordered mesoporous carbon could improve the performance of Pt.We synthesized the ordered mesoporous carbon with addition of cobaltous acetate as assisted catalyst. We find that the addition of appropriate cobaltous doesn’t destroy the ordered mesoporous structure of carbon. The metallic Co, which was come from carbonization, could form many active points on the surface of ordered mesoporous carbon. It is benefit for the loading of Pt. The CV tests indicated that the highest active surface area of modified carbon supported Pt catalyst reached to 128.7m2g-1. It indicated that during the preparation process, the addition of appropriate cobalt salt in ordered mesoporous carbon could also improve the performance of Pt.In order to reduce the quantity and improve the use ratio of Pt, the paper also put attention on the Pt catalyst self, we synthesized Co@Pt/XC-72 and Ni@Pt/XC-72 nanoparticles with a confirmed core-shell structure, based on a two steps glycol microwave reduction method and a galvanic replacement method, respectively. The core-shell structure catalyst could augment the active surface area and the utilization rate of Pt. The CV tests indicated that the active surface area of Co@Pt/XC-72 and Ni@Pt/XC-72 catalysts are 84.3m2g-1 and 100.1m2g-1, respectively, which are higher than pure Pt catalyst.To sum up, all the above three methods can improve the activity of catalyst effectively. They have a good prospect of application in proton exchange membrane fuel cell catalysts aspect.更多还原