碳化钨作为Pd、Pt催化剂载体对小分子有机物的电催化氧化

发布时间：2018-04-16 01:09

本文选题：Pd + Pt　；参考：《哈尔滨师范大学》2015年硕士论文

【摘要】：燃料电池被公认为是一种高效绿色的能源技术,它不经过热机过程,因此不受卡诺循环的限制,能量转换效率高,环境污染小,被认为是21世纪首选的清洁、高效的发电技术。尽管低温燃料电池近年来已经取得了很大的研究进展,但离商业化还有一定距离。电催化剂的活性和稳定性是影响直接型燃料电池性能的最关键因素之一。提高催化剂的活性和稳定性能较大程度的提高整个电池的电化学性能。催化剂的稳定性除了与催化剂活性组分相关外,还与催化剂载体材料以及催化剂的负载方法有关,特别是活性组分和载体间的相互作用密切相关。本文以具有良好导电性和高比表面积Vulcan XC-72R活性碳作为碳源,采用浸渍及高温热处理还原法,在活性碳表面原位还原钨酸铵,形成表面包覆钨的碳化物结构的载体。并以制备的C@WC为载体制备Pd基催化剂和Pt基催化剂。讨论了不同W:C原子比对制备C@WC载体性能的影响,以及不同制备方法对催化剂性能的影响。研究发现,当W:C原子比为1:10、1:15和1:20制备出的C@WC-6、C@WC-7和C@WC-8载体中元素钨的主要存在形式是WC和W2C;由C@WC制备出的催化剂有较高电催化氧化活性。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、热重(TG)等手段对载体C@WC进行了表征。通过XRD方法对催化剂载体的组成进行了分析;用循环伏安法(CV),计时电流曲线法(CA),此外还通过电势阶跃法,对催化剂活性衰减及稳定性进行了讨论。比较了常规化学合成法及微波辅助催化剂合成法对制备的Pd/C@WC催化剂的影响,研究发现,采用常规化学合成法制备的电催化剂对甲酸的电催化氧化具有更高的活性和稳定性。比较了W:C原子比为1:10、1:15和1:20载体的电化学性质和表面形貌;并比较了制备出的Pd/C@WC-6、Pd/C@WC-7和Pd/C@WC-8催化剂对甲酸的电催化氧化性能,发现C@WC-7为载体制备的催化剂对甲酸的氧化具有最高的活性和稳定性。以C@WC-6、C@WC-7和C@WC-8为载体制备了Pt/C@WC-6、Pt/C@WC-7和Pt/C@WC-8催化剂,分别研究了这三种催化剂对甲醇和乙醇的电催化氧化性能,发现C@WC-7作为载体制备的催化剂Pt/C@WC-7对甲醇和乙醇的氧化具有最好的电催化活性和稳定性。
[Abstract]:Fuel cell is recognized as a kind of efficient green energy technology, it does not go through heat engine process, so it is not restricted by Carnot cycle, energy conversion efficiency is high, environmental pollution is small, it is considered to be the first choice of clean and efficient power generation technology in the 21st century.Although cryogenic fuel cells have made great progress in recent years, they are still far from commercialization.The activity and stability of electrocatalyst is one of the most important factors affecting the performance of direct fuel cell.The electrochemical performance of the whole battery was improved greatly by improving the activity and stability of the catalyst.The stability of the catalyst is not only related to the active component of the catalyst, but also to the support material and the method of the catalyst support, especially the interaction between the active component and the support.In this paper, Vulcan XC-72R active carbon with good electrical conductivity and high specific surface area was used as carbon source. In this paper, ammonium tungstate was reduced in situ on the surface of activated carbon by impregnation and high temperature heat treatment.PD-based catalysts and Pt-based catalysts were prepared on C@WC.The effects of different W: C atomic ratios on the properties of C@WC support and the effects of different preparation methods on the performance of the catalysts were discussed.It is found that when the W: C atom ratio is 1: 10 / 1: 15 and 1:20, the main forms of tungsten in the support of CWC-6R CWC-7 and C@WC-8 are WC and W2C.The catalysts prepared from C@WC have higher electrocatalytic oxidation activity.The C@WC was characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TG).The composition of catalyst support was analyzed by XRD method, and the catalytic activity attenuation and stability were discussed by cyclic voltammetry, chronoelectric curve method and potential step method.The effects of conventional chemical synthesis and microwave-assisted catalyst synthesis on the preparation of Pd/C@WC catalysts were compared. It was found that the electrocatalysts prepared by conventional chemical synthesis had higher activity and stability for the electrocatalytic oxidation of formic acid.The electrochemical properties and surface morphology of the supports with a W: C ratio of 1: 10 to 1: 15 and 1:20 were compared, and the electrocatalytic oxidation of formic acid over PD / CWC-6W / C / C @ WC-7 and Pd/C@WC-8 catalysts were compared.It was found that the catalyst prepared with C@WC-7 as the carrier had the highest activity and stability for the oxidation of formic acid.Using CWC-6C @ CWC-7 and C@WC-8 as the supports, the catalytic properties of the three catalysts for the electrocatalytic oxidation of methanol and ethanol were studied.It was found that the catalyst Pt/C@WC-7 prepared with C@WC-7 as the carrier had the best electrocatalytic activity and stability for the oxidation of methanol and ethanol.
【学位授予单位】：哈尔滨师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TM911.4

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