苯胺类导电聚合物与碳材料复合电极在电催化氧化甲醇及甲酸中的应用

发布时间：2018-06-07 13:21

  本文选题：直接甲醇燃料电池 + 直接甲酸燃料电池　； 参考：《华东师范大学》2017年硕士论文

【摘要】：近年来,燃料电池由于其能量转化率高,环境稳定性好等优点受到了人们的广泛关注。液体燃料电池因其运输便利,储存简单的优点也促进了有机小分子作为新的可替代能源的发展。甲醇与甲酸分子中不含C-C键且具有较高的氢碳比,为其在低温下的完全氧化提供了合理的氧化动力学机理。以上这些优点都促进了直接甲醇燃料电池(DMFC)及直接甲酸燃料电池(DFAFC)做为新的便携式能源转化装置的发展。目前,在直接甲醇燃料电池与直接甲酸燃料电池中具有最好电催化性能的催化剂为Pt催化剂。然而Pt为贵金属存储有限、成本较高且甲醇与甲酸在Pt表面的氧化过程较为复杂易产生CO_ads造成催化剂中毒,这就限制了直接甲醇燃料电池与直接甲酸燃料电池的商业化进展。为了改变这一现状,降低Pt纳米颗粒的负载量,降低成本,提高其催化效率,可以选择比表面积大,可降低催化剂负载量的电极材料来负载Pt催化剂,如高度石墨化的碳材料、导电聚合物材料等。碳材料具有导电性好,比表面积大,稳定性好等优点被广泛用作电极材料。除此之外,导电聚合物(CPs)作为新型的有机半导体材料,具有较大的比表面积和较好的稳定性近年来也常用来负载和分散燃料电池的催化剂Pt。在众多的导电聚合物中聚苯胺(PANI)及其衍生物易在电极表面合成,在酸性介质中稳定,因此常被用来负载燃料电池的催化剂Pt。本论文制备出碳糊电极(CPE)和电池活性炭掺杂碳糊电极(YBCPE)并研究其与聚邻甲氧基苯胺(POA)相结合负载Pt纳米颗粒对甲醇的电催化氧化的影响。其次还选用不同的碳材料电极分别与聚邻甲氧基苯胺(POA)和聚邻氨基苯酚(POAP)相结合负载Pt纳米颗粒电催化氧化甲酸,研究底电极材料,导电聚合物的种类及导电聚合物的制备方法对复合电极电催化氧化甲酸的影响。以下是本论文初步研究的一些内容:(1)电池活性炭掺杂碳糊电极的电化学行为及其电催化氧化甲醇的研究用石墨粉,电池活性炭和石蜡油作为原材料制备出碳糊电极(CPE)和掺杂不同含量电池活性炭的(YBCPE)电极。并试图用电化学交流阻抗技术对制备出的碳糊电极和电池活性炭掺杂碳糊电极的可逆性和电荷转移情况进行定性和定量的研究。同时将制备好的底电极负载金属Pt得到Pt/YBCPE复合电极并用于甲醇的电催化氧化,用SEM对得到的Pt复合电极形貌进行表征。研究表明YBCPE比CPE具有更小的电荷转移电阻,对催化剂Pt具有更好的分散作用。Pt/YBCPE复合电极电催化氧化甲醇的活性先随掺杂电池活性炭含量的增加而增加,随后再减小。其中Pt/YBCPE(14%)对甲醇具有最好的电催化氧化活性。(2)聚邻甲氧基苯胺修饰电池活性炭掺杂碳糊电极电催化氧化甲醇的研究将已经制备好的CPE和YBCPE(14%)用聚邻甲氧基苯胺膜(POA)进行修饰并用来负载Pt纳米颗粒,得到Pt/POA/YBCPE复合电极。将得到的Pt/POA/YBCPE复合电极用于甲醇的电催化氧化,对比Pt/POA/YBCPE复合电极与Pt/YBCPE复合电极电催化氧化甲醇活性的高低。用TEM对复合电极上Pt的分散情况进行表征,对比研究POA膜的存在对催化剂在电极表面分散情况的影响。通过电化学交流阻抗技术研究POA/YBCPE电极与电解质溶液界面间的电荷转移情况及Pt/POA/YBCPE电极与电解质溶液界面之间的电荷转移情况。除此之外还系统性的研究邻甲氧基苯胺单体的浓度、聚邻甲氧基苯胺的膜厚度等因素对复合电极电催化氧化性能的影响。研究结果表明,POA膜的存在会影响Pt在电极表面的成核情况,有利于Pt纳米颗粒的分散,增加复合电极的电化学活性比表面积,使复合电极的电催化氧化活性提高。(3)Pt/CPOA/GC,Pt/CPOA/YBCPE,Pt/POA/GC,Pt/POA/YBCPE 复合电极对甲酸电催化氧化的研究选用YBCPE(14%)与玻碳电极(GC)为底电极分别在YBCPE(14%)及GC电极上用循环伏安法或恒电位电解法制备聚邻甲氧基苯胺膜(分别表示为CPOA和POA),得到 CPOA/YBCPE,POA/YBCPE,CPOA/GC 和 POA/GC 电极。并将 Pt电沉积在这些电极上,将得到的复合电极用于甲酸的电催化氧化。比较研究底电极材料及制备方法对复合电极电催化氧化甲酸活性和机理的影响。实验结果表明,当用循环伏安法制备POA膜时,Pt/CPOA/YBCPE比Pt/CPOA/GC对甲酸有更好的电催化氧化活性。当用恒电位电解法制备POA膜时,Pt/POA/GC比Pt/POA/YBCPE对甲酸有更好的电催化氧化活性。在本实验条件下Pt/POA(40mC)/GC与Pt/POA(40mC)/YBCPE复合电极对甲酸具有较好的电催化氧化活性和稳定性。(4)初步探究了聚邻甲氧基苯胺的电化学制备方法对Pt/聚邻甲氧基苯胺/碳材料复合电极电催化氧化甲酸活性的影响主要研究了在相同的碳材料电极上用循环伏安法和恒电位电解法制备相同膜厚度的CPOA和POA膜。研究其负载Pt纳米颗粒后对甲酸电催化氧化活性和稳定性的影响。用电化学交流阻抗手段研究不同制备方法对CPOA/碳材料电极和POA/碳材料电极的电荷转移情况和表面粗糙度。并用TEM对催化剂的分散情况进行表征。其实验结果表明当底电极材料相同时恒电位电解法制备的POA膜比循环伏安法制备的CPOA膜有更小的电荷转移电阻,表面粗糙度更小,更有利于载铂后复合电极对甲酸的电催化氧化。(5)聚邻氨基苯酚修饰碳材料电极载铂后电催化氧化甲酸行为研究选用GC与YBCPE(14%)为底电极,用循环伏安法制备聚邻氨基苯酚膜(CPOAP),得到CPOAP/GC与CPOAP/YBCPE电极,将得到的电极负载Pt纳米颗粒用于甲酸的电催化氧化研究。同时对比了聚邻甲氧基苯胺与聚邻氨基苯酚膜对甲酸电催化氧化活性的影响,并用TEM对聚邻甲氧基苯胺膜和聚邻氨基苯酚膜上Pt纳米颗粒的分散情况进行研究。实验结果表明,在本实验的实验条件下CPOA比CPOAP更易合成,对Pt具有更好的分散作用。所以用CPOA负载Pt纳米颗粒比用CPOAP负载Pt纳米颗粒对甲酸具有更好的电催化氧化活性。
[Abstract]:In recent years, fuel cells have attracted wide attention because of their high energy conversion and good environmental stability. Because of their convenient transportation and simple storage, liquid fuel cells have also promoted the development of small organic molecules as a new alternative energy source. Methanol and formic acids have no C-C bonds and have high hydrogen carbon ratio. The complete oxidation at low temperature provides a reasonable oxidation kinetic mechanism, which all promote the development of the direct methanol fuel cell (DMFC) and the direct formic fuel cell (DFAFC) as a new portable energy conversion device. At present, it has the best electrocatalysis in the direct methanol fuel cell and the direct formic fuel cell. The performance catalyst is Pt catalyst. However, Pt is limited in the storage of precious metals, the cost is high and the oxidation process of methanol and formic acid on the Pt surface is more complex and easy to produce CO_ads to cause catalyst poisoning. This restricts the commercialization of direct methanol fuel cells and direct formic acid fuel cells. In order to change this situation, reduce Pt nanoscale. The load of grain, reducing cost and improving its catalytic efficiency can be used to load Pt catalyst, such as highly graphitized carbon material and conductive polymer material, which have large surface area and can reduce the load of catalyst, such as highly graphitized carbon material, conductive polymer material and so on. The carbon material has many advantages, such as good conductivity, large surface area, good stability and so on. In addition, the conductive polymer (CPs), as a new organic semiconductor material, has a larger specific surface area and better stability. In recent years, the catalyst Pt. is often used to load and disperse the catalyst of the fuel cell. Polyaniline (PANI) and its derivatives are easily synthesized on the surface of the electrode in many conductive polymers and are stable in acid medium, so they are often used. The carbon paste electrode (CPE) and battery activated carbon doped carbon paste electrode (YBCPE) were prepared in this paper, and the effect of Pt nanoparticles on the electrocatalytic oxidation of methanol was studied. Secondly, the different carbon material electrodes and poly (o methoxy) aniline (POA) were used in Pt.. Electrocatalytic oxidation of formic acid with poly (o-aminophenol) (POAP) loaded Pt nanoparticles was used to study the effects of the base electrode materials, the types of conductive polymers and the preparation methods of conducting polymers on the electrocatalytic oxidation of formic acid by composite electrodes. The following are the internal capacity of the preliminary study in this paper: (1) electrochemical oxidation of activated carbon doped carbon paste electrode The behavior and electrocatalytic oxidation of methanol used graphite powder, battery activated carbon and paraffin oil as raw materials to prepare carbon paste electrode (CPE) and (YBCPE) electrode doped with different content of battery active carbon, and try to use electrochemical impedance technique to prepare the carbon paste electrode and the reversibility and charge of the battery activated carbon doped carbon paste electrode. The transfer situation was studied qualitatively and quantitatively. At the same time, the Pt/YBCPE composite electrode was obtained by the prepared base electrode loaded metal Pt and used for the electrocatalytic oxidation of methanol. The morphology of the Pt composite electrode obtained by SEM was characterized. The study shows that YBCPE has a smaller charge transfer resistivity than CPE and has a better dispersion effect on the catalyst Pt.Pt. The activity of electrocatalytic oxidation of methanol by /YBCPE composite electrode increased first with the increase of the content of activated carbon in the doped cell, and then decreased. Among them, Pt/YBCPE (14%) had the best electrocatalytic oxidation activity to methanol. (2) the study on the electrocatalytic oxidation of methanol by the active carbon doped carbon paste electrode of the polyo methoxy aniline modified battery would have been prepared for a good CPE And YBCPE (14%) was modified with polyo-methoxy aniline membrane (POA) and used to load Pt nanoparticles and get Pt/POA/YBCPE composite electrode. The Pt/POA/YBCPE composite electrode was used for electrocatalytic oxidation of methanol. The activity of methanol oxidation by Pt/POA/YBCPE composite electrode and Pt/YBCPE composite electrode was compared with that of Pt/YBCPE composite electrode. On the composite electrode, TEM was used on the composite electrode. The dispersion of Pt was characterized, and the influence of the presence of POA film on the dispersion of the catalyst on the surface of the electrode was compared. The charge transfer between the interface of the POA/YBCPE electrode and the electrolyte solution and the charge transfer between the Pt/POA/YBCPE electrode and the electrolyte solution interface were investigated by electrochemical impedance spectroscopy. The influence of the concentration of o-methoxy aniline monomer and the film thickness of poly (o-methoxy) aniline on the electrocatalytic oxidation performance of the composite electrode was investigated. The results showed that the existence of POA film would affect the nucleation of Pt on the surface of the electrode, be beneficial to the dispersion of Pt nanoparticles and increase the specific surface area of the electrochemical activity of the composite electrode. The electrocatalytic oxidation activity of the composite electrode is improved. (3) the study on the electrocatalytic oxidation of formic acid by Pt/CPOA/GC, Pt/CPOA/YBCPE, Pt/POA/GC, Pt/POA/YBCPE composite electrodes, YBCPE (14%) and glassy carbon electrode (GC) are used as the base electrodes to prepare polyo methoxy aniline membranes by cyclic voltammetry or constant potential electrolysis on YBCPE (14%) and GC electrodes respectively. As CPOA and POA), CPOA/YBCPE, POA/YBCPE, CPOA/GC and POA/GC electrodes were obtained. And Pt was deposited on these electrodes and the composite electrodes were used for the electrocatalytic oxidation of formic acid. The effects of the substrate and preparation methods on the activity and mechanism of the electrocatalytic oxidation of formic acid at the composite electrode were compared. When the POA film is prepared by the volt ampere method, Pt/CPOA/YBCPE has better electrocatalytic oxidation activity to formic acid than Pt/CPOA/GC. When the POA film is prepared by constant potential electrolysis, Pt/POA/GC has better electrocatalytic oxidation activity to formic acid than Pt/POA/YBCPE. The Pt/POA (40mC) /GC and Pt/POA (40mC) /YBCPE composite electrodes have better electricity for formic acid under this experimental condition. Catalytic oxidation activity and stability. (4) the effect of electrochemical preparation of poly (o methoxy) aniline on the activity of electrocatalytic oxidation of formic acid by Pt/ polymethoxy aniline / carbon composite electrode was mainly studied. The CPOA and POA of the same film thickness were prepared by cyclic voltammetry and constant potential electrolysis on the same carbon electrode. The effects of the Pt nanoparticles on the activity and stability of the electrocatalytic oxidation of formic acid were investigated. The charge transfer and surface roughness of the CPOA/ carbon material electrode and the POA/ carbon electrode were investigated by electrochemical impedance spectroscopy. The dispersion of the catalysts was characterized by TEM. The experimental results showed that the dispersion of the catalysts was characterized by the electrochemical impedance method. The POA films prepared by constant potential electrolysis at the same bottom electrode materials have smaller charge transfer resistance than the CPOA films prepared by cyclic voltammetry, with smaller surface roughness and more favorable for electrocatalytic oxidation of formic acid by composite electrodes after platinum loading. (5) study on the behavior of electrocatalytic oxidation of formic acid after electropolar platinum modification of polyo aminophenol modified carbon materials by G C and YBCPE (14%) were used as the base electrode to prepare polyo-aminophenol membrane (CPOAP) by cyclic voltammetry. The CPOAP/GC and CPOAP/YBCPE electrodes were obtained. The electrocatalytic oxidation of the electrode loaded Pt nanoparticles was used to study the electrocatalytic oxidation of formic acid. The effect of polyo-methoxy aniline and polyo-aminophenol film on the activity of Formic acid electrooxidation was compared, and TEM was compared with TEM. The dispersion of Pt nanoparticles on polyo-methoxy aniline film and polyo-aminophenol film is studied. The experimental results show that under the experimental conditions, CPOA is more easily synthesized than CPOAP, and has a better dispersion effect on Pt. So CPOA loaded Pt nanoparticles have better electrical activity to formic acid than CPOAP negative Pt nanoparticles. Oxidative activity.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4
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本文编号：1991315