碳纳米管负载钯基复合纳米催化剂的制备及其电催化活性

发布时间：2018-05-12 12:57

本文选题：燃料电池 + 化学还原法　；参考：《湖南科技大学》2015年硕士论文

【摘要】：燃料电池是能直接将化学能转化成电能的发电装置,是一种高效、环保的发电技术,在当今资源紧缺的背景下,具有重要研究意义。直接醇燃料电池分别以醇类和氧气为燃料和氧化剂,具有燃料多样、携带方便、易于储存等特点。Pt作为燃料电池的催化剂因价格昂贵、易中毒等问题而受到限制,Pd的价格相对便宜,且在碱性溶液中对醇类氧化具有较高的电催化活性,因此,开发新型Pd基催化剂成为人们研究关注的重点。本文研究了PdSnNi、PdAg催化剂的制备,采用各种表征方法,观察了催化剂的晶型结构、表面形貌以及粒径大小,并研究了催化剂对乙醇、丙醇和丁醇(简称C2-C4醇)氧化的活性和对氧还原反应(ORR)的活性。以PdSnNi/MWCNT为阳极催化剂,组装了无膜直接醇燃料电池,并测试了其放电性能。本论文研究的主要内容包括以下几个方面:(1)采用化学还原法,以酸化碳纳米管为载体,硼氢化钠为还原剂,制备了Pd/MWCNT、PdSn/MWCNT、PdNi/MWCNT、PdSnNi/MWCNT催化剂,采用TEM、XRD等表征方法对所制备的催化剂进行了表征,通过循环伏安、计时电流等电化学测试方法,在碱性环境中对C2-C4醇的氧化活性和稳定性进行了测试。结果表明:PdSnNi/MWCNT催化剂对各类醇的氧化表现出最好的电催化活性,其中对乙醇最大氧化电流密度为83.2 mA·cm-2,对正丙醇的最大氧化电流密度为142.5mA·cm-2,对正丁醇的最大氧化电流密度为76.2mA·cm-2,且正丙醇和正丁醇的氧化效果分别好于其异构体的氧化。(2)采用循环伏安、线性扫描等电化学测试方法研究了Pd/MWCNT、PdSn/MWCNT、PdNi/MWCNT、PdSnNi/MWCNT催化剂对氧还原反应的活性。结果表明:无论在碱性还是酸性溶液中,PdNi/MWCNT催化剂表现出最佳的ORR活性,在碱性溶液中,PdNi/MWCNT的起始电位为-0.08V,在转速为2000 rpm时,其极限扩散电流密度为3.51 mA·cm-2,在酸性溶液中,PdNi/MWCNT的起始电位为0.61V,在转速为2000 rpm时,其极限扩散电流密度为4.44 mA·cm-2,表明PdNi/MWCNT是一种对ORR活性较好的催化剂,有望作为燃料电池的阴极材料。(3)采用化学还原法,以酸化碳纳米管为载体,硼氢化钠为还原剂,制备了Pd/MWCNT、Pd4Ag1/MWCNT、Pd2Ag1/MWCNT、Pd1Ag1/MWCNT催化剂,采用TEM、XRD等表征方法对所制备的催化剂进行了表征,通过循环伏安电化学测试方法,改变不同醇的浓度以及反复循环扫描次数,在碱性环境中对C2-C4醇的氧化活性和稳定性进行了测试,结果表明:Pd4Ag1/MWCNT催化剂对各类醇的氧化表现出最好的活性,其中对乙醇最大氧化电流密度为102.7 mA·cm-2,对正丙醇的最大氧化电流密度为162.7 mA·cm-2,对正丁醇的最大氧化电流密度为84.8mA·cm-2,且正丙醇和正丁醇的氧化效果分别好于其异构体的氧化。(4)以PdSnNi/MWCNT催化剂为阳极材料,高温热解法制备的FeCo/C-PANI催化剂为阴极材料,组装了以空气为燃料的无膜直接醇燃料电池,通过测试表明:以乙醇、正丙醇、异丙醇、正丁醇、异丁醇和仲丁醇为燃料时,燃料电池的开路电压依次为0.68V、0.69V、0.61V、0.50V、0.51V、0.48V,其中正丙醇为燃料时,电池的电流功率密度最大,为0.51W g(Pd)-1。
[Abstract]:Fuel cell is a power generating device that can convert chemical energy into electric energy directly. It is an efficient and environmentally friendly power generation technology. It has important research significance in the background of resource shortage today. Direct alcohol fuel cells use alcohols and oxygen as fuel and oxidizing agent respectively, which have the characteristics of.Pt as fuel, easy to carry, easy to store and so on. The catalyst of the battery is limited because of the high price, easy poisoning and so on. The price of Pd is relatively cheap, and it has high electrocatalytic activity for alcohols oxidation in alkaline solution. Therefore, the development of new Pd based catalysts has become the focus of attention. The preparation of PdSnNi, PdAg catalyst is studied in this paper, and various characterization methods are used in this paper. The crystal structure, surface morphology and particle size of the catalyst were investigated, and the activity of the catalyst to ethanol, propanol and butanol (C2-C4 alcohol) oxidation and the activity of oxygen reduction reaction (ORR) were investigated. The film free direct alcohol fuel cell was assembled with PdSnNi/MWCNT as the anode catalyst and its discharge performance was tested. The main research in this paper was in this paper. The contents are as follows: (1) using chemical reduction method, using the acidified carbon nanotube as the carrier and the sodium borohydride as the reducing agent, Pd/MWCNT, PdSn/MWCNT, PdNi/MWCNT, PdSnNi/MWCNT catalyst are prepared, and the catalysts are characterized by TEM, XRD and so on. The electrochemical testing methods, such as cyclic voltammetry, timing current and so on, are used. The oxidation activity and stability of C2-C4 alcohol were tested in the alkaline environment. The results showed that the PdSnNi/MWCNT catalyst showed the best electrocatalytic activity for the oxidation of all kinds of alcohols. The maximum oxidation current density for ethanol was 83.2 mA. Cm-2, the maximum oxidation electric current density for n-propanol was 142.5mA. Cm-2, and the maximum oxygen of n-butanol was obtained. The current density is 76.2mA. Cm-2, and the oxidation effect of n-propanol and n-butanol is better than the oxidation of its isomers. (2) the activity of Pd/MWCNT, PdSn/MWCNT, PdNi/MWCNT, PdSnNi/MWCNT catalyst for oxygen reduction reaction is studied by cyclic voltammetry and linear scanning. The results show that the activity of the catalyst is in alkaline or acid solution. In the alkaline solution, the starting potential of PdNi/MWCNT is -0.08V. At the speed of 2000 rpm, the limiting diffusion current density is 3.51 mA. Cm-2. In the acid solution, the starting potential of PdNi/MWCNT is 0.61V, and the limit diffusion current density is 4.44 mA. At the speed of 2000 rpm, the initial diffusion current density is 4.44 mA. PdNi/MWCNT is a good catalyst for ORR activity, which is expected to be the cathode material for fuel cells. (3) chemical reduction method, acidified carbon nanotubes as the carrier, sodium borohydride as reducing agent, prepared Pd/MWCNT, Pd4Ag1/MWCNT, Pd2Ag1/MWCNT, Pd1Ag1/MWCNT catalyst, using TEM, XRD and other characterization methods for the preparation of the catalyst. By means of cyclic voltammetry, the oxidation activity and stability of C2-C4 alcohol are tested in alkaline environment by changing the concentration of different alcohols and the frequency of repeated cycle scanning. The results show that the Pd4Ag1/MWCNT catalyst shows the best activity for the oxidation of various alcohols, and the maximum oxidation current density for ethanol is the same. 102.7 mA. Cm-2, the maximum oxidation current density for n-propanol is 162.7 mA. Cm-2, the maximum oxidation current density of n-butanol is 84.8mA. Cm-2, and the oxidation effect of n-butanol and n-butanol is better than the oxidation of its isomers respectively. (4) the PdSnNi/MWCNT catalyst is the anode material and the FeCo/C-PANI catalyst prepared by high temperature pyrolysis is the cathode material. Material, a non film direct alcohol fuel cell with air as fuel is assembled. The test shows that the open circuit voltage of fuel cell is 0.68V, 0.69V, 0.61V, 0.50V, 0.51V, 0.48V when ethanol, n-propanol, isopropanol, isobutanol and SEC butanol are used as fuel, and the current power density of the battery is the largest when n-propyl alcohol is fuel, which is 0.51W G. (Pd) -1.

【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TB383.1

【参考文献】