双金属纳米颗粒的化学法制备及其对甲醇的催化研究

发布时间：2018-04-09 01:21

本文选题：燃料电池　切入点：双金属　出处：《湖南大学》2011年硕士论文

【摘要】：直接甲醇燃料电池(DMFC)采用甲醇为燃料,解决了困扰人们的氢气的储存,运输等问题。当前DMFC商业化面临的主要问题是Pt价格高,电催化剂活性低,电催化剂长期稳定性有待进一步提高。本文从开发新型电催化剂和提高电催化剂催化活性入手,开展了多壁碳纳米管(MWCNT)负载地Pd基和Pt基双金属催化剂的化学法制备和对甲醇的电催化氧化研究。研究工作主要包括如下三个方面: 1.利用HAuCl4溶液与新制的Pd胶发生置换反应,制备了六种原子比的Pd-Au双金属纳米颗粒再负载于MWCNT上,制得MWCNT/Pd-Au双金属催化剂,通过透射电子显微镜(TEM),能量色散X-射线光谱(EDS)和紫外可见分光光度计(UV-vis)对制备的MWCNT/Pd-Au催化剂进行了形貌表征,并采用循环伏安法考察了不同Au: Pd原子比MWCNT/Pd-Au催化剂对甲醇的电催化氧化性能。结果表明,所制备的6种MWCNT/Pd-Au双金属催化剂对甲醇氧化的催化性能都明显优于单一金属催化剂MWCNT/Pd或MWCNT/Au的催化性能。Au: Pd原子比不同导致MWCNT/Pd-Au双金属催化剂的催化效果也不相同,随着Au: Pd原子比数值的上升,MWCNT/Pd-Au双金属催化剂对甲醇氧化的催化活性先升后降,当Au:Pd原子比为0.06时,MWCNT/ Pd-Au双金属催化剂的催化活性最大且抗中毒性能最好。 2.在无还原剂存在的情况下,用HAuCl4溶液与负载在MWCNT上的Pd纳米颗粒发生置换反应,制备了Pd: Au原子比不同的五种MWCNT/Pd-Au双金属纳米颗粒,并应用于碱性条件下甲醇的电催化氧化。通过等离子体发射光谱(ICP),TEM和EDS对制备的MWCNT/Pd-Au催化剂进行了原子比和形貌的表征,用循环伏安法考察了不同Pd: Au原子比的MWCNT/Pd-Au催化剂对甲醇的电催化氧化性能,并与单一金属催化剂MWCNT/Pd和MWCNT/Au的催化性能进行比较。结果表明,制备的5种MWCNT/Pd-Au双金属催化剂对甲醇氧化的催化性能均优于单一金属催化剂MWCNT/Pd或MWCNT/Au的催化性能,Pd: Au原子比不同导致MWCNT/Pd-Au双金属催化剂催化效果也不相同,随着Pd: Au原子比数值的上升,MWCNT/Pd-Au双金属催化剂对甲醇氧化的催化活性先升后降,当Pd: Au原子比为48时MWCNT/Pd-Au双金属催化剂的催化活性最好且具有较好的抗中毒性能。 3.采用KBH4还原的方法在水溶液中制备了负载在MWCNT上的原子比为3:1的MWCNT/Pt-Cu,MWCNT/Pt-Ni和MWCNT/Pt-Co双金属催化剂,再利用HNO3溶解贱金属的方法制备了比双金属催化剂反应表面积更大的MWCNT/Pt(Cu),MWCNT/Pt(Co),MWCNT/Pt(Ni)催化剂,将这六种不同催化剂应用于酸性条件下甲醇的电催化氧化。采用TEM考察了MWCNT/Pt(Cu)催化剂的形貌并与MWCNT/Pt-Cu进行比较,采用循环伏安曲线和i-t曲线比较了这六种催化剂对甲醇电催化氧化的性能和抗中毒性能。结果表明,这六种催化剂都具有良好的酸性条件下电化学催化甲醇氧化的功能,MWCNT/Pt(Cu)催化剂具有最好的催化活性和较好的抗中毒能力。
[Abstract]:Direct methanol fuel cell (DMFC) uses methanol as fuel to solve the problems of hydrogen storage and transportation.At present, the main problems facing the commercialization of DMFC are the high price of Pt, the low activity of electrocatalyst, and the long-term stability of electrocatalyst need to be further improved.In this paper, the preparation and electrocatalytic oxidation of methanol with multi-walled carbon nanotubes (MWCNT) supported PD and Pt-based bimetallic catalysts were studied by developing new electrocatalysts and improving their catalytic activity.The research includes the following three main areas:1.Six kinds of Pd-Au bimetallic nanoparticles with different atomic ratios were prepared by substitution reaction of HAuCl4 solution with new PD colloid on MWCNT to prepare MWCNT/Pd-Au bimetallic catalyst.The morphology of the prepared MWCNT/Pd-Au catalyst was characterized by TEM, energy dispersive X- ray spectroscopy (EDS) and UV-vis spectrophotometer.The electrocatalytic oxidation of methanol over MWCNT/Pd-Au catalysts with different au: PD atomic ratios was investigated by cyclic voltammetry.The results showed that the catalytic performance of the six MWCNT/Pd-Au bimetallic catalysts for methanol oxidation was obviously better than that of single metal catalyst MWCNT/Pd or MWCNT/Au. The catalytic activity of MWCNT/Pd-Au bimetallic catalyst was also different due to the difference of atomic ratio of au: PD.The catalytic activity of MWCNT / Pd-Au bimetallic catalyst for methanol oxidation increased first and then decreased with the increase of au: PD atomic ratio. When the Au:Pd atom ratio was 0.06, the catalytic activity of MWCNT / Pd-Au bimetallic catalyst was the highest and the resistance to poisoning was the best.2.In the absence of reductant, five kinds of MWCNT/Pd-Au bimetallic nanoparticles with different PD: au atomic ratios were prepared by displacement reaction between HAuCl4 solution and PD nanoparticles loaded on MWCNT. The results were applied to the electrocatalytic oxidation of methanol under alkaline conditions.The atomic ratio and morphology of the prepared MWCNT/Pd-Au catalysts were characterized by TEM and EDS. The electrocatalytic oxidation of methanol over MWCNT/Pd-Au catalysts with different PD: au atomic ratios was investigated by cyclic voltammetry.The catalytic performance of MWCNT/Pd and MWCNT/Au was compared with that of single metal catalyst.The results showed that the catalytic performance of the five MWCNT/Pd-Au bimetallic catalysts for methanol oxidation was better than that of single metal catalyst MWCNT/Pd or MWCNT/Au. The catalytic performance of MWCNT/Pd-Au bimetallic catalyst was also different due to the difference of PD: au atom ratio.With the increase of PD: au atom ratio, the catalytic activity of MWCNT / Pd-Au bimetallic catalyst for methanol oxidation first increased and then decreased. When PD: au atom ratio was 48, the catalytic activity of MWCNT/Pd-Au bimetallic catalyst was the best and had better antipoisoning performance.3.The MWCNT / Pt-Cu MWCNT / Pt-Ni and MWCNT/Pt-Co bimetallic catalysts supported on MWCNT with an atomic ratio of 3:1 on MWCNT were prepared by KBH4 reduction method. The MWCNT / PtCT-Cu / MWCNT / MWCNT/Pt-Co bimetallic catalysts with larger surface area than bimetallic catalysts were prepared by the method of HNO3 dissolution.These six catalysts were applied to the electrocatalytic oxidation of methanol under acidic conditions.The morphology of MWCNT / PttCuCu catalyst was investigated by TEM and compared with that of MWCNT/Pt-Cu. The performance and antipoisoning performance of MWCNT / PtCuCu catalyst for methanol electrooxidation were compared by cyclic voltammetry curve and i-t curve.The results show that all of the six catalysts have the best catalytic activity and the ability to resist poisoning.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：O643.32;TM911.4

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