贵金属纳米粒子复合催化剂的合成及其对醇类的电催化氧化中文摘要
摘要
燃料电池作为一种环境友好的能源转换装置，其燃料范围广，转换效率高，可以有效的缓解当前全球面临的环境污染和能源危机，得到了越来越多的关注。催化剂（包括载体和金属催化剂）是燃料电池的重要组成部件之一，是发生催化反应的活性中心，其性能的优劣会直接影响燃料电池的整体性能和工作效率。目前，在燃料电池中使用最普遍的阳极催化剂是贵金属铂，但其在地球上含量少，价格高，易毒化，严重限制了燃料电池的商业化发展。因此，降低贵金属的用量，提高催化剂的催化活性一直是燃料电池的研究热点。改变催化剂催化性能可以从贵金属和载体两方面出发。一般在贵金属中掺杂第二种元素，利用电子效应或/和双金属协同效应，提高催化性能；另一方面是研发高比表面积、高稳定性、低成本的载体，提高贵金属的分散性，增大贵金属的电化学活性面积，提高催化剂的催化活性。
本文从提高催化剂催化活性入手，通过化学方法合成了一系列催化剂，并研究了所合成的催化剂对小分子醇类的电催化氧化能力。主要研究了以下几方面内容：
(1) 使用苯甲醇为溶液，以次亚磷酸钠为磷源制备了不同比例的Pd/P纳米催化剂。通过一系列的物理及电化学方法对所合成的Pd/P催化剂进行了表征测试。电镜结果显示Pd/P催化剂为网状结构，电化学测试表明，相比于单金属Pd或商业的Pd/C 催化剂，磷掺杂的Pd催化剂对甲醇具有较好的电催化氧化活性和抗毒化性能，当加入的Pd/P原子比为2:1时，其效果最佳。
(2) 以抗坏血酸为还原剂，KBr为结构导向剂合成贵金属纳米催化剂。通过XRD、TEM和XPS等方法对所制备的Pd/Ru纳米催化剂进行表征，TEM图像表明合成的Pd/Ru纳米催化剂为枝晶状。对比实验结果表明KBr及Ru的加入对枝晶状的形成具有重要作用。电化学测试得出Pd/Ru纳米催化剂对乙醇具有良好的电化学活性与稳定性。
(3) 采用“一锅法”简单快速的合成了树突状Pt/Pb纳米催化剂，并通过TEM、XRD、XPS和电化学等测试方法对所制备的树突状Pt/Pb纳米催化剂进行了分析。对比实验证明了CTAC的加入对树突状结构的形成必不可少。电化学测试结果表明，与单金属Pt和商业Pt/C催化剂相比，树突状Pt/Pb纳米催化剂对乙醇电催化氧化有更好的催化活性和抗毒化性能，当Pt/Pb的比例为1:1时，催化效果最佳。
(4) 在Cu3P修饰的石墨烯(Cu3P/RGO)上负载Pd纳米粒子，制备了Pd/Cu3P/RGO 复合催化剂。采用SEM、XPS、XRD、TEM和电化学方法对所制备的Pd/Cu3P/RGO
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中文摘要贵金属纳米粒子复合催化剂的合成及其对醇类的电催化氧化复合催化剂进行了表征和测试。一系列的电化学测试结果说明，在碱性条件下，Pd/Cu3P/RGO复合催化剂比商业的Pd/C和Pd/RGO催化剂对醇类有更高的电催化氧化和抗毒化性能。
(5) 以合成的管状PANI为骨架，利用硼氢化钠同时还原氧化石墨烯与氯金酸，合成了三维的Au/PANI/RGO催化剂。通过SEM、TEM、Raman和XPS等方法对所制备的Au/PANI/RGO催化剂的形貌和结构进行了表征。电化学测试结果表明，相比于Au/RGO和Au/PANI催化剂，Au/PANI/RGO催化剂对乙醇具有良好的电催化氧化能力，说明PANI/RGO有望作为催化剂载体实现其在燃料电池上的应用。
关键词：燃料电池，纳米催化剂，甲醇，乙醇，电催化氧化
作者：章柯
指导老师：杜玉扣教授
II
贵金属纳米粒子复合催化剂的合成及其对醇类的电催化氧化英文摘要Synthesis of noble metal composite catalysts and their
electrocatalysis toward alcohols
Abstract
Fuel cell is a kind of eco-friendly energy conversion equipment. Because of the wide range of fuel and high conversion efficiency, fuel cell is an effective choice to solve environmental pollution and energy crisis. As an important part of fuel cell, Electrocatalysts (including catalyst support and noble metal) is the active center of the catalytic reaction, and the performance will directly affect the overall performance and efficiency of the fuel cells. Currently, the most commonly used anode catalyst in fuel cells is platinum, however, the poor anti-poisonous and high cost of Pt seriously impede the development of fuel cell. Therefore, developing suitable catalyst supports, decreasing the amount of noble metals and improving the electrocatalytic activity have always been hot topics in fuel cell study. The electrocatalytic activity of the catalyst can be improved from two aspects, precious metals and catalyst supports. Generally, doping second element in noble metal can change the electronic structure of noble metal and improve the catalyst performance. Another aspect is developing high specific surface area, high stability and low-cost catalyst support, which makes the precious metal disperse evenly, and ultimately improves the unit activity of the noble metal.
In this dissertation, a series of electrocatalysts were synthesized through chemical methods, and the catalytic activities of the as-synthesized electrocatalysts toward alcohols oxidation have been explored in detail. The main content in this thesis is listed in the following:
(1) Pd/P nanocomposite catalysts with different Pd/P ratios were synthesized by using benzyl alcohol as solution and sodium hypophosphite as phosphorus source. The as-prepared catalysts were characterized by a series of physical and electrochemical methods. Electron microscope results showed that the obtained Pd/P catalyst possess well-defined network structure. The electrochemical results demonstrate that P doped Pd nanocatalyst has the superior electrocatalytic activity toward methanol oxidation in comparison with the monometallic Pd and commercial Pd/C catalyst, and the optimal molar ratio of Pb/P catalysts
III
英文摘要贵金属纳米粒子复合催化剂的合成及其对醇类的电催化氧化
is 2:1.
(2) Dendritic Pd/Ru nanocatalysts have been synthesized by using ascorbic acid as reducing agent and KBr as directing agent. The as-prepared Pd/Ru nanocatalysts have been characterized by XRD, TEM and XPS, the characterization measurements reveal that KBr and Ru play crucial roles in synthesizing the dendritic structure of the catalyst. Electrochemical results show that the Pd/Ru catalyst has the superior catalytic activity and stability toward ethanol electrooxidation reaction.
(3) Dendritic Pt/Pb nanocatalysts were facile and rapid synthesized by a one-pot method. The obtained catalysts were analyzed by TEM, XRD, XPS and electrochemical measurements. By controlling the growth parameter, we found that CTAC plays a crucial role in synthesizing the dendritic structure of the catalyst. Electrochemical test results show that the dendritic Pt/Pb catalysts possess the best catalytic performance than the monometallic Pt and commercial Pt/C catalyst for ethanol oxidation reaction, and the optimal molar ratio of Pt/Pb catalysts is 1:1.
(4) Pd/Cu3P/RGO nanocomposite catalyst was synthesized by depositing Pd nanoparticles on Cu3P modified RGO. The as-formed Pd/Cu3P/RGO nanocomposite catalyst was extensively analyzed by SEM, XPS, XRD, TEM and electrochemical measurement methods. Electrochemical test results demonstrate that the as-synthesized Pd/Cu3P/RGO catalyst possesses the best catalytic activity and stability toward alcohols electrooxidation under alkaline condition in comparison with commercial Pd/C and Pd/RGO catalysts.
(5) A three-dimensional Au/PANI/RGO catalyst, which uses the tubular PANI as skeleton, was synthesized by chemical reduction of graphene oxide and chloroauric acid with sodium borohydride. The structure and morphology of the Au/PANI/RGO was characterized by SEM, TEM, Raman and XPS. Electrochemical test results reveal that the Au/PANI/RGO nanocatalyst provides superior electrocatalytic activity toward ethanol oxidation as compared to Au/PANI and Au/RGO, demonstrating that PANI/RGO can be used as a catalyst supporting material in direct ethanol fuel cells.
Key words: Fuel cells, Nanocatalysts, Methanol, Ethanol, Electrocatalytic oxidation
IV
贵金属纳米粒子复合催化剂的合成及其对醇类的电催化氧化英文摘要
V Written by: Ke Zhang Supervised by: Prof.Yukou Du
目录
摘要................................................................................................................................................. I 第一章绪论 (1)
1.1 燃料电池概述 (1)
1.1.1直接甲醇燃料电池 (4)
1.1.2直接乙醇燃料电池 (4)
1.2 燃料电池贵金属催化剂 (4)
1.2.1 双组分/多组分催化剂 (6)
1.2.2结构和形貌控制 (8)
1.3 燃料电池催化剂载体 (13)
1.3.1 炭黑 (13)
1.3.2 金属氧化物 (13)
1.3.3 导电高分子 (14)
1.3.4石墨烯 (17)
1.4选题意义、主要研究内容及创新点 (22)
1.4.1选题意义 (22)
1.4.2 主要研究内容 (22)
1.4.3 创新点 (23)
参考文献 (24)
第二章实验部分 (39)
2.1 实验试剂与仪器 (39)
2.1.1试剂和材料 (39)
2.1.2仪器 (41)
2.2 复合催化剂的制备 (41)
2.3 催化剂的物理表征 (42)
2.3.1 扫描电镜(SEM) 测试 (42)
2.3.2 透射电镜(TEM) 测试 (42)
2.3.3 X-射线衍射(XRD) 测试 (42)
2.3.4 Raman光谱 (42)
2.3.5 XPS光谱 (42)
2.4 催化剂的电化学测试 (43)
2.4.1电化学实验装置 (43)
2.4.2 催化剂电化学性能测试 (43)
第三章网状Pd/P纳米粒子的合成及其对甲醇的电催化氧化 (44)
3.1 引言 (44)
3.2实验部分 (45)
3.2.1 试剂与仪器 (45)
3.2.2 Pd/P 催化剂的制备 (45)
3.3结果和讨论 (45)
3.4 本章小结 (53)
参考文献 (53)
第四章Ru协助合成枝晶状Pd/Ru纳米催化剂及其对乙醇的电催化性能研究 (59)
4.1 引言 (59)
4.2实验部分 (60)
4.2.1 试剂与仪器 (60)
4.2.2 Pd/Ru催化剂的制备 (60)
4.3结果和讨论 (60)
4.4 本章小结 (67)
参考文献 (67)
第五章快速合成树突状Pt/Pb纳米颗粒及其对乙醇的电催化氧化 (72)
5.1 引言 (72)
5.2 实验部分 (73)
5.2.1 试剂与仪器 (73)
5.2.2树突状Pt/Pb纳米粒子的合成 (73)
5.2.3商品化Pt/C墨水的制备 (73)
5.3 结果与讨论 (73)
5.4 本章小结 (79)
参考文献 (80)
第六章Cu3P/RGO提升Pd纳米粒子对醇类的电催化氧化性能 (84)
6.1 引言 (84)
6.2 实验部分 (85)
6.2.1 试剂与仪器 (85)
6.2.2 催化剂的制备 (85)
6.3 结果与讨论 (86)
6.4 本章小结 (93)
参考文献 (93)
第七章PANI/RGO负载的链状Au纳米催化剂的合成及其对乙醇的电催化氧化 (98)
7.1 引言 (98)
7.2 实验部分 (99)
7.2.1 试剂与仪器 (99)
7.2.2 PANI的合成 (99)
7.2.3 Au/PANI/RGO催化剂的制备 (99)
7.3 结果与讨论 (99)
7.4 本章小结 (106)
参考文献 (107)
第八章论文工作总结与展望 (111)
8.1 主要结论 (111)
8.2 研究展望 (112)
攻读博士学位期间发表的论文 (113)
国内外核心学术刊物上发表的论文 (113)
致谢 (116)