铂（钯）基多孔纳米合金催化剂的制备及其电催化性能研究

发布时间：2018-03-17 03:21

本文选题：燃料电池　切入点：合金催化剂　出处：《信阳师范学院》2017年硕士论文　论文类型：学位论文

【摘要】：Pt、Pd因对甲醇等有机小分子有很好的电催化氧化能力,是目前广泛使用的燃料电池催化剂。但由于Pt、Pd资源稀少、价格昂贵,阻碍了燃料电池的商业化发展。并且Pt在电催化氧化过程中极易被CO中间产物毒化,从而降低催化活性。因此,开发低Pt、Pd负载量的燃料电池催化剂,提高催化剂的催化活性和抗中毒能力,在推动燃料电池商业化方面显得尤为重要。本论文从降低贵金属用量、增大催化剂比表面积入手,制备了一系列具有特殊形貌的多孔Pt、Pd基合金催化剂。通过SEM、TEM、物理吸附仪等仪器,对所制备材料进行结构表征,通过电化学测试,分析所制备催化剂对甲醇、甲酸的电催化性能,并取得了以下研究成果:1、在无表面活性剂的情况下,合成了高度均一,且粒径大小约为500 nm的锯齿状多枝Pd3Cu纳米合金催化剂,由XPS、XRD、EDS等分析手段得出,Pd、Cu两种元素比例为3:1。其性能较商业钯黑相比,具有相当好的催化性能和稳定性。2、通过水热法,利用乙二醇对前驱体进行还原,改变前驱体Na2PdCl4、CuCl2·2H2O用量,制备出不同比例,具有3D网状结构的Pd-Cu合金催化剂。利用物理吸附仪对合金比表面积分析,得出Pd51Cu49和Pd76Cu24的比表面积分别为20.7m2·g-1和10.4 m2·g-1。电化学测试显示Pd51Cu49具有更大的电化学活性面积。较钯黑相比,对甲酸的电催化性能更优。3、利用嵌段共聚物P123作为结构导向剂,合成了具有多孔结构的球形网状Pt PdCu合金,比表面高达86.9 m2·g-1。此材料不仅包含了多孔结构在电化学催化过程中具有的高传质能力和气体渗透率,而且也弥补了传统多孔结构较长的物质和离子传输距离,大大降低了过电位,使电极表面动力学反应更好的进行。4、为进一步降低贵金属用量,减少催化剂制作成本。我们又制备了具有多孔结构的PtSnCu合金催化剂。Sn的加入可以在催化剂表面产生吸附态的OH,从而使CO2的转化效率提高。并且,Cu随电化学测试圈数的增加,可逐渐溶出,形成富Pt的催化表面,暴露更多的催化活性位点,显著增强催化剂催化性能。是很具前景的合金催化剂。
[Abstract]:PTN PD is widely used as a fuel cell catalyst for its excellent electrocatalytic oxidation ability to small organic molecules such as methanol, but it is expensive because of its scarce resources. This hinders the commercial development of fuel cells, and Pt is easily poisoned by CO intermediates during electrocatalytic oxidation, which reduces the catalytic activity. Therefore, low PtPd supported fuel cell catalysts are developed. It is very important to promote the commercialization of fuel cell by improving the catalytic activity and anti-poisoning ability of the catalyst. In this paper, we start with reducing the amount of noble metal and increasing the specific surface area of the catalyst. A series of porous PtPd-based alloy catalysts with special morphology were prepared. The structure of the prepared materials was characterized by means of SEMMOTEM and physical adsorption apparatus. The electrocatalytic properties of the catalysts for methanol and formic acid were analyzed by electrochemical tests. The following research results were obtained: 1. In the absence of surfactants, the sawtooth multi-branched Pd3Cu nanocrystalline catalysts with high homogeneity and size of about 500nm were synthesized. The ratio of two elements of PdCU and Cu was found to be 3: 1 by means of XPSN XRDX EDS. Compared with commercial palladium black, its catalytic performance and stability were better. By hydrothermal method, the precursor was reduced by ethylene glycol, and the amount of Na2PdCl4CuCl2 路2H2O was changed, and the content of the precursor Na2PdCl4CuCl2 路2H2O was changed by hydrothermal method. Pd-Cu alloy catalysts with different proportions and 3D mesh structure were prepared. The specific surface area of the alloy was analyzed by physical adsorption apparatus. The specific surface areas of Pd51Cu49 and Pd76Cu24 were 20.7 m2 路g-1 and 10.4 m2 路g-1.Electrochemical tests showed that Pd51Cu49 had a larger electrochemical active area. Compared with palladium black, the electrocatalytic activity of Pd51Cu49 was better than that of palladium black. The block copolymer P123 was used as structural guide. Spherical reticulated Pt PdCu alloy with porous structure was synthesized, with a specific surface of 86.9 m2 路g-1.This material not only contains the high mass transfer capacity and gas permeability of porous structure in electrochemical catalytic process. It also makes up for the longer material and ion transport distance of the traditional porous structure, greatly reduces the overpotential, and makes the kinetic reaction on the electrode surface better. 4, in order to further reduce the amount of precious metals, In addition, the addition of PtSnCu alloy catalyst with porous structure can produce adsorptive OHs on the surface of the catalyst, thus increasing the conversion efficiency of CO2, and the Cu content increases with the increase of the number of electrochemical test cycles. It can be dissolved gradually to form Pt rich catalyst surface, expose more catalytic activity sites, and significantly enhance the catalytic performance of the catalyst. It is a promising alloy catalyst.
【学位授予单位】：信阳师范学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4

【参考文献】