低铂—非金属复合催化剂的构筑和性能研究

发布时间：2018-08-09 18:27

【摘要】：质子交换膜燃料电池是目前最接近商业化的一种燃料电池,它具有能量转换效率高,环境友好,可持续供电,噪声低,使用方便灵活等特点,但是在实现商业化大规模生产的道路上,质子交换膜燃料电池还面临着成本过高和稳定性差的两大问题亟待解决。针对这些问题,本工作从提高Pt的利用率,增强催化剂稳定性的方面入手,进行了一系列探索。聚多巴胺和聚苯胺是一类导电高聚物,它们在高温下可以分解产生类石墨烯的NC结构层。本工作拟在催化剂表面生成这种NC结构层,一方面通过NC结构对铂纳米粒子形成保护层,使Pt/C催化剂具有更好的稳定性,另一方面,利用NC结构与Pt纳米粒子的微观结构、表面状态等产生影响,以提高催化剂的催化活性。首先,将聚多巴胺包覆在Pt/C催化剂表面,并进行高温焙烧,使其在高温下分解,生成NC的多孔结构包覆在Pt/C催化剂的表面,在这过程中,采用Na Cl重固结晶固型法,利用Na Cl的限域作用,减少3D结构的季铵氮的生成,最终得到类石墨烯NC结构层包覆的Pt/C@NC催化剂。电化学测试表明,制备的Pt/C@NC催化剂与20%的商业化Pt/C催化剂相比,电化学活性表面积提高13.7%,半波电位正移了39m V,质量比活性和比表面活性分别为20%的商业化Pt/C催化剂的3.6倍和3.0倍。加速老化实验结果表明,经过2000圈循环伏安测试后,制备的Pt/C@NC催化剂电化学活性表面积减少了15.43%,优于商业化Pt/C催化剂的42.51%。其次,将Pt/C催化剂吸附Fe3+离子,然后包覆一层聚苯胺层,再在Si O2的保护下进行800oC的高温焙烧,最后利用Na OH溶液刻蚀除去Si O2层,得到Pt Fe@NC催化剂。制备的Pt Fe@NC催化剂活性纳米粒子均匀的分布在载体表面,呈现中空的纳米结构。循环伏安曲线可以看出,制备的Pt Fe@NC催化剂循环伏安曲线表现出超大的双电层的特征,说明其具有良好的导电性。从线性扫描曲线中可以看出,制备的Pt Fe@NC催化剂反应的起始电位比商业化Pt/C催化剂提前了48m V,半波电位正移了18m V,质量比活性为商业化Pt/C催化剂的0.96倍,两者相当。在加速老化测试中,经过1000圈循环伏安扫描,曲线几乎没有变化,表现出良好的稳定性,线性扫描曲线半波电位负移16m V,仍与新鲜的商业化Pt/C催化剂相当,但是极限电流变大。
[Abstract]:Proton exchange membrane fuel cell (PEMFC) is one of the most commercialized fuel cells. It has the characteristics of high energy conversion efficiency, environment friendly, sustainable power supply, low noise and easy to use and flexible. On the road to commercialize large-scale production, proton exchange membrane fuel cell is also faced with high cost and poor stability of two. In order to solve these problems, a series of exploration has been made to improve the utilization of Pt and enhance the stability of the catalyst. Polyamine and polyaniline are a kind of conductive polymers which can decompose the NC structure of graphene like structure at high temperature. This work is to produce this NC junction on the surface of the catalyst. On the one hand, the protective layer of platinum nanoparticles is formed by the NC structure, which makes the Pt/C catalyst have better stability. On the other hand, the structure of the NC is affected by the microstructure of the Pt nanoparticles, the surface state and so on, in order to improve the catalytic activity of the catalyst. First, the polydopamine is coated on the surface of the Pt/C catalyst and roasted at high temperature. By decomposing it at high temperature, the porous structure of NC is coated on the surface of the Pt/C catalyst. In this process, the Na Cl recrystallization solidification method is used to reduce the formation of the quaternary ammonium nitrogen in the 3D structure by using the limiting effect of Na Cl, and the Pt/C @NC catalyst coated with the structure layer of the graphene NC is finally obtained. The electrochemical test shows that the preparation of Pt/C@NC catalysis is shown. Compared with 20% commercialized Pt/C catalyst, the electrochemical activity surface area is increased by 13.7%, the half wave potential is moving 39m V, the mass ratio is 3.6 times and 3 times that of the commercial Pt/C catalyst with the specific surface activity and the specific surface activity, respectively. The accelerated aging test results show that the electrochemical activity of the prepared Pt/C@NC catalyst after 2000 cycles of volt ampere test The surface area was reduced by 15.43%, which was better than the 42.51%. of commercialized Pt/C catalyst. The Pt/C catalyst was adsorbed on the Fe3+ ion, then a polyaniline layer was coated, then the 800oC was calcined under the protection of Si O2. The Si O2 layer was removed by the Na OH solution etching, and the Pt catalyst was obtained. The cyclic voltammetry curve shows that the prepared Pt Fe@NC catalyst cyclic voltammetry curve shows the characteristics of the super large double layer, indicating that it has good conductivity. It can be seen from the linear scanning curve that the starting potential of the prepared Pt Fe@NC catalyst is more than commercial P. The t/C catalyst is 48m V ahead of time, and the half wave potential is moving forward 18m V, and the mass ratio is 0.96 times of the commercial Pt/C catalyst. In the accelerated aging test, the curve is almost unchanged after 1000 ring cyclic voltammetry, showing good stability, the linear sweep curve half wave potential negative shift 16m V, and the fresh commercialized Pt/C. The catalyst is equal, but the limit current becomes larger.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TM911.4

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