锡掺杂二氧化钛纳米材料促进甲醇电氧化性能的研究

发布时间：2018-03-06 05:09

本文选题：直接甲醇燃料电池　切入点：Pt/Ti1-xSnxO2　出处：《黑龙江大学》2015年硕士论文　论文类型：学位论文

【摘要】：直接甲醇燃料电池(DMFC)因其较高的能量密度、适宜的操作环境、简易的操作过程以及几乎为零的污染物排放,得到广泛关注和研究。但是其阳极催化剂仍存在问题亟需解决,包括相对较高的成本、催化剂活性位点易被毒化、催化活性低以及催化剂稳定性差等。本文引入Sn掺杂TiO2(Sn-TiO2)固溶体到DMFC阳极催化剂中作为助剂和载体,以提高催化剂的催化活性和稳定性。本文对所制备的引入Sn-TiO2后的催化剂进行了物理化学性能表征和电化学测试,并详细讨论了其对催化剂催化活性和稳定性的促进原理。(1)利用溶胶-水热法制备了不同掺杂比例的Sn-TiO2(Ti O2、Ti0.9Sn0.1O2、Ti0.8Sn0.2O2和Ti0.7Sn0.3O2),并将其与Vulcan XC-72 carbon black机械混合作为Pt催化剂的载体。探讨了不同掺杂比例和不同“氧化物/C”比例对催化剂甲醇电氧化效果的影响。筛选出Sn掺杂比例为10%、“氧化物/C”比例为15:35的催化剂(Pt/Ti0.9Sn0.1O2 C70)作为主要研究对象,通过循环伏安(CV)、计时电流(CA)CO溶出伏安等电化学测试手段考察了Pt/Ti0.9Sn0.1O2 C70催化剂的甲醇电氧化催化活性和稳定性。通过XPS分析,Sn元素的掺入使氧化物表面对含氧官能团的吸附能力增强,进而增强了氧化物在催化剂工作时的“双功能机理”作用。同时使有利于催化剂催化活性和稳定性的“三相界面”结构更容易形成。(2)将锐钛矿Ti O2分散在10 mol L 1的NaOH溶液中进行水热反应得到钛酸钠纳米管,经过酸洗和水洗,得到钛酸纳米管。将得到的钛酸纳米管加入到SnCl4的乙醇溶液中进行离子交换得到Sn4+离子掺杂的钛酸纳米管,经过焙烧后得到Sn掺杂TiO2纳米管(Sn-TNT)。将其与Vulcan XC-72 carbon black混合作为Pt催化剂的复合载体,得到甲醇电氧化催化剂Pt/Sn-TNT C。通过电化学测试可以得出,Pt/Sn-TNT C相比较于Pt/Ti0.9Sn0.1O2 C具有更高的甲醇电氧化催化活性。经分析,混有钛酸或TiO2(B)晶型的管状锡掺杂二氧化钛比颗粒状氧化物具有更高的电子传导性,同时,其对水分子的吸附能力加强。(3)以氢氟酸为氟源,采用浸渍焙烧法对Sn掺杂TiO2纳米管做进一步修饰。将修饰后的氧化物(Sn-F-TNT)与炭黑混合,将Pt负载其上作为甲醇电氧化催化剂(Pt/Sn-F-TNT/C)。与Pt/Sn-TNT/C催化剂做对比,研究其电催化性能,结果表明,Pt/Sn-F-TNT/C样品具有较高的抗CO中毒能力,而Pt/Sn-TNT/C的甲醇电氧化效果与Pt/Sn-F-TNT/C相近。分析原因,F元素并没有进入氧化物晶格,以表面吸附的状态存在,提高了氧化物表面的电负性。从而促进了氧化物表面含氧物种浓度的提升和Pt颗粒在载体上的均匀分散。
[Abstract]:Direct methanol fuel cell (DMFC) has been widely studied for its high energy density, suitable operating environment, simple operation process and almost zero pollutant emission. However, the anode catalyst still needs to be solved. Including relatively high cost, the active sites of the catalyst are easily poisoned, the catalytic activity is low and the stability of the catalyst is poor. In this paper, Sn-doped TiO2Sn-TiO2) solid solution was introduced to the DMFC anode catalyst as a promoter and carrier. In order to improve the catalytic activity and stability of the catalysts, the physicochemical properties and electrochemical tests of the catalysts after the introduction of Sn-TiO2 were investigated. The mechanism of promoting the catalytic activity and stability of the catalyst was discussed in detail. (1) Sn-TiO2(Ti O _ 2 O _ 2O _ 2 Ti _ (0.9) Sn _ (0.1) O _ (2) O _ (2) Ti _ (0.8) Sn _ (0.2) O _ (2) and Ti _ (0.7) Sn _ (0.3) O _ (2) O _ (2) and Vulcan XC-72 carbon black were mechanically mixed with Vulcan XC-72 carbon black as the support of Pt catalyst. The effect of different doping ratio and different "oxide / C" ratio on the electrooxidation of methanol was investigated. The catalyst Pt- / Ti0.9Sn0.1O2 / C70 with Sn doping ratio of 10 and "oxide / C" ratio of 15:35 was selected as the main research object. The catalytic activity and stability of Pt/Ti0.9Sn0.1O2 C70 catalyst for methanol electrooxidation were investigated by means of cyclic voltammetry (CV) and chronoamperometric voltammetry (CV) and chronoamperometric stripping voltammetry. The oxygen functional groups on the surface of the oxide were determined by XPS analysis with the addition of Sn element. Enhanced adsorption capacity, Thus, the "double function mechanism" of oxide in catalyst operation is enhanced. At the same time, the "three-phase interface" structure, which is favorable to the catalytic activity and stability of the catalyst, is easier to form. 2) anatase TIO _ 2 is dispersed in 10 mol L. Sodium titanate nanotubes were obtained by hydrothermal reaction in the NaOH solution of T-1. After acid washing and water washing, titanic acid nanotubes were obtained. The obtained titanate nanotubes were added to the ethanol solution of SnCl4 for ion exchange to obtain Sn4 ion-doped titanate nanotubes. Sn-doped TiO2 nanotubes were prepared by calcination. Sn-TNT black was mixed with Vulcan XC-72 carbon black as the composite support of Pt catalyst. The methanol electrooxidation catalyst Pt/Sn-TNT C was obtained. By electrochemical test, it can be concluded that Pt- Sn-TNT / C has higher catalytic activity than Pt/Ti0.9Sn0.1O2 C in methanol electrooxidation. The tubular tin doped TIO _ 2 mixed with titanic acid or TIO _ 2B has higher electron conductivity than granular oxide. Meanwhile, its adsorption ability to water molecules is enhanced. [WT5HZ] hydrofluoric acid is used as fluorine source, and hydrofluoric acid is used as fluorine source. Sn-doped TiO2 nanotubes were further modified by impregnation roasting method. The modified oxide Sn-F-TNT was mixed with carbon black, and Pt was supported as methanol electrooxidation catalyst PtSn-F-TNT / Con. Compared with Pt/Sn-TNT/C catalyst, its electrocatalytic performance was studied. The results show that the Pt- Sn-F-TNT / C sample has a higher ability to resist CO poisoning, while the effect of methanol electrooxidation of Pt/Sn-TNT/C is similar to that of Pt/Sn-F-TNT/C. The reason is that element F does not enter the oxide lattice and exists in the state of adsorption on the surface. The electronegativity of the oxide surface is improved, thus the oxygen species concentration on the oxide surface and the uniform dispersion of Pt particles on the surface of the oxide are promoted.
【学位授予单位】：黑龙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM911.4;TB383.1

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