贵金属改性的NPG催化剂对甲醇甲酸催化氧化性能的研究

发布时间：2018-04-01 07:20

本文选题：甲醇　切入点：甲酸　出处：《曲阜师范大学》2015年硕士论文

【摘要】：近些年,由于直接甲醇燃料电池(DMFC)和直接甲酸燃料电池(DFAFC)具有价格便宜,燃料来源丰富,运输和储存安全的优点而受到广泛重视,但是,DMFC和DFAFC的阳极催化剂的催化活性较低,而且甲醇和甲酸的氧化中间产物羰基会对阳极催化剂产生毒化作用,导致DMFC和DFAFC的实际应用发展速度一直比较缓慢。因此,研究和发展高催化活性,抗中毒能力强的新型催化剂已成为当前DMFC发展的关键技术。大量研究发现,可以通过多元金属之间的协同作用来改进铂催化剂的活性和稳定性,从而制成铂基复合催化剂(如Pt-Ru,Pt-Sn,Pt-Ni,Pt-Ir等)。首先采用直接电化学沉积法以纳米多孔金膜(NPG)作为载体,由于电化学沉积法具有能够实现将金属催化剂选择性的沉积在既有电子通道,又有离子传输通道的与质子膜接触的载体上,显示了比传统的以质子交换膜电解质溶液粘接在Pt/C催化剂上的方法更高的催化剂利用率。其次研究发现第二种金属的加入不但是一种良好的双效氧电极催化剂组分,而且作为直接醇类燃料电池的阳极催化剂也具有较好的抗中毒性能。因此,我们利用恒电位沉积合成技术在Pt NPG中引入Ir、Ni、Bi得到Pt/M NPG催化剂,利用在一系列含Pt、M物质的量配比不同的溶液中恒电位沉积制备形成的一系列催化剂对甲醇和甲酸进行电化学性能测试,结果表明Pt基电催化剂中添加适量的Ir、Ni、Bi对于甲醇、甲酸的电催化氧化性能有明显提高,优于纯Pt NPG催化剂,且具有较好的循环寿命,以及时间稳定性。本文分别以H2PtCl6.6H2O和IrCl3.3H2O、H2PtCl6.6H2O和NiSO4.6H2O、H2PtCl6.6H2O和BiNO3.5H2O作为金属来源,以NPG作为基底,采用电化学扫描电沉积法制备活性较高的NPG/PtIr、NPG/PtNi、NPG/PtBi二元复合纳米催化剂,并利用XRD和SEM技术表征了催化剂粒子大小、结晶度,采用电化学方法评价了NPG/PtIr、NPG/PtNi、NPG/PtBi二元复合纳米催化剂对甲醇甲酸的电催化氧化活性和稳定性。主要研究结果如下:首先在三电极体系下,采用恒电位共沉积方法制备出高分散的NPG/PtIr、NPG/PtNi、NPG/PtBi催化剂,利用XRD和SEM技术表征了修饰在NPG膜上的PtIr、PtNi、PtBi催化剂颗粒的大小、分散状态,由XRD和SEM结果显示,PtIr纳米粒子高度分散NPG膜表面,以膜的形成方式包被在NPG催化剂表面,PtNi、PtBi在NPG表面凸起分别形成花状和钮扣状的颗粒。利用循环伏安电化学方法评价了该电极催化剂对甲醇、甲酸的电催化氧化活性和稳定性,电化学测试结果表明NPG/PtIr和NPG/PtBi催化剂对甲醇、甲酸的电催化氧化呈现出很好的活性和稳定性,NPG/PtNi催化剂对甲醇效果较好。这主要是由于Pt、M和NPG之间的协同催化作用使甲醇、甲酸氧化中间产物的毒化物种易氧化成最终产物的结果,其次是用这种方法制得的催化剂中各组分具有较小的粒径,且分散较好。电化学性能显示其中Pt:Ir=3:2的Pt/Ir NPG催化剂对于直接甲醇、甲酸燃料电池具有最佳的电催化氧化性能,其中Pt:Ni=1:1的Pt/Ni NPG催化剂对于直接甲醇、甲酸燃料电池具有最佳的电催化氧化性能,其中Pt:Bi=9:1的Pt/Bi NPG催化剂对于直接甲醇、甲酸燃料电池具有最佳的电催化氧化性能。本论文所研制的几种二元复合纳米结构电催化剂对甲醇和甲酸的电催化氧化具有高催化活性和稳定性。同时降低了贵金属铂的载量,Ir、Ni、Bi的引入使催化剂抗CO中毒的性能又取得进一步提高,研究表明二元复合纳米催化剂在DMFC和DFAFC中有良好的发展前景。
[Abstract]:In recent years, due to the direct methanol fuel cell (DMFC) and direct formic acid fuel cell (DFAFC) has the advantages of low price, abundant fuel source, has the advantages of safe storage and transportation and received extensive attention, but the catalytic activity of the anode catalyst of DMFC and DFAFC is low, and methanol and formic acid oxidation carbonyl will produce toxic effect the anode catalyst, lead to practical application development speed of DMFC and DFAFC has been slow. Therefore, the research and development of new catalysts with high catalytic activity and anti poisoning ability has become a key technology in the development of DMFC. A lot of studies have found that it is possible to improve the platinum catalyst by the synergistic effect of multi metal between activity and stability, thus made of platinum based composite catalysts (such as Pt-Ru, Pt-Sn, Pt-Ni, Pt-Ir). The direct electrochemical deposition in nanoporous gold film (NPG) as a carrier, because The electrochemical deposition method can realize deposition of metal catalyst selectivity in both electron and ion channel, carrier transmission channel and proton membrane contact on the catalyst shows higher than the traditional method of using proton exchange membrane electrolyte solution adhesive on Pt/C catalyst utilization. Secondly we found that adding second kinds of metal not only a good set of bifunctional oxygen electrode catalyst, and as anode catalyst of direct methanol fuel cell also has good anti poisoning performance. Therefore, we use constant potential deposition technology is introduced in the Pt Ir, NPG Ni, Bi Pt/M NPG catalyst, used in a series containing a series of Pt. The catalyst solution M molar ratio in different potentiostatic deposition preparation formed by electrochemical performance test of methanol and formic acid, the results show that the Pt based electrocatalysts in addition Ir, Ni, Bi in methanol, the electrocatalytic oxidation of formic acid was higher than that of pure Pt NPG catalyst, and has good cycle life, time and stability. In this paper, H2PtCl6.6H2O and IrCl3.3H2O, H2PtCl6.6H2O and NiSO4.6H2O, H2PtCl6.6H2O and BiNO3.5H2O as the metal source, using NPG as substrate by electrochemical scanning electro deposition preparation of high activity of NPG/PtIr, NPG/PtNi, NPG/PtBi two composite nano catalyst, and the characterization of the catalyst particle size, XRD and SEM crystallinity by electrochemical method, evaluation of NPG/PtIr, NPG/PtNi, NPG/PtBi two composite catalysts for methanol electro catalytic oxidation of formic acid on activity and stability. The main results are as follows: first of all in three electrode system, by constant potential co deposition method of high dispersion of NPG/PtIr, NPG/PtNi, NPG/, PtBi catalyst, using XRD and SEM Technology Characterization of modified NPG membrane in PtIr, PtNi, PtBi, catalyst particle size, dispersion state, by the XRD and SEM results showed that the highly dispersed NPG film on the surface of PtIr nanoparticles to form a way was coated on the surface of the NPG catalyst, PtNi film, PtBi the formation of flower like and button shaped particles on the surface of NPG were raised using cyclic voltammetry method to evaluate the electrode catalyst for methanol, formic acid electrocatalytic oxidation activity and stability, electrochemical testing results showed that the NPG/PtIr and NPG/PtBi catalysts for methanol electrocatalytic oxidation of formic acid showed good activity and stability of NPG/PtNi catalyst for methanol, better effect. This is mainly due to Pt, synergistic catalysis the interaction of M and NPG of the methanol, formic acid oxidation of the intermediate product of the oxidation easily poisoning species into the final product, followed by each catalyst prepared by the method of having a smaller Particle size and well dispersed. The electrochemical properties of the Pt/Ir NPG display Pt:Ir=3:2 catalyst for direct methanol fuel cell with formic acid, electrocatalytic oxidation of the best performance, the Pt/Ni NPG Pt:Ni=1:1 catalyst for direct methanol fuel cell with formic acid, electrocatalytic oxidation of the best performance, the Pt/Bi NPG Pt:Bi=9:1 catalyst for direct formic acid fuel methanol. The battery has the best performance. The electrocatalytic oxidation of electro catalytic oxidation of several developed in this paper the two element composite nanostructure electrocatalysts for methanol and formic acid has high catalytic activity and stability. At the same time, reduce the load, Pt Ir, Ni, the performance of Bi into the catalyst poisoning and further anti CO to improve, research shows that two yuan nanocomposite catalyst has a good development prospect in DMFC and DFAFC.

【学位授予单位】：曲阜师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM911.4;O643.36

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