【作者】 张兵；

【导师】 钟起玲；

【作者基本信息】 江西师范大学 ， 有机化学， 2004， 硕士

【摘要】 本文较系统地研究了乙醇在粗糙铂和铂钌电极上解离吸附与氧化行为，设计合成铂基纳米粒子催化剂，制备纳米粒子修饰的铂基电极，初步地研究了甲酸、甲醇、一氧化碳分子在这些电极上的电催化形为，拓宽了表面增强拉曼光谱（SERS）技术的应用范围。采用TEM、XRD、SAED、UV-Visible、AFM等手段较系统地表征了所合成的铂包金纳米粒子和碳纳米管负载的铂纳米粒子的结构、尺寸及光学性能，运用常规电化学和和SERS技术研究这些铂基电极的电催化性能及SERS形为。本论文工作主要出以下四部分组成： 1．基于乙醇的电氧化在醇类燃料电池中有极其重要的作用，运用CV和SERS技术系统地研究电极粗糙度、乙醇浓度、电极电位以及溶液pH值对乙醇解离吸附行为的影响，首次发现乙醇能在粗糙铂电极上会自发地解离出强吸附物种CO，首次获得了乙醇在粗糙Pt电极上解离吸附的表面拉曼光谱。结果还表明：pH值和支持电解质对乙醇的解离吸附有重要的影响；电极的粗糙度及扫描速度对乙醇在粗糙铂电极上的CV行为有显著的影响，乙醇在粗糙铂上的氧化受扩散步骤控制；在碱性介质中观察到了乙醇解离吸附产生CO的桥式和线性相互转换这一有趣现象；根据原位表面增强拉曼光谱和稳态电流的数据，证实了酸性介质中粗糙Pt上乙醇的电氧化是按照双途径反应机理进行的。本部分的工作拓展了SERS技术在C2分子的电催化领域中的应用。 2．在粗糙铂电极上沉积钌和在玻碳基底上沉积铂钌合金来制备两种不同的Pt-Ru电极，分别首次获得乙醇和甲酸在这两种电极上解离吸附和氧化的拉曼谱图。结果表明有钌的存在能增强铂在乙醇、甲酸等小分子中的电催化活性，通过CV、计时电流等常规电化学及表面增强拉曼光谱技术简要地讨论了钌含量的影响。在CV图中钌的氧化峰及拉曼谱图中低波数区位于～600 cm^-1处谱峰的存在，为双功能机理提供了一定的证据。在铂钌修饰的玻碳电极上，除了检测到强吸附物种CO的信号外，还在～1380 cm^-1处检测到强度较弱甲酸氧化的活性中间体的信号，进一步证实了甲酸是通过双途径机理进行了。 3．用种子法合成了尺寸可控、单分散性好、且具有核壳结构的铂包金纳米粒子（20-150 nm），并通过组装得到类似粗糙铂电极表面结构的Au_core-Pt_shell／GC电极。结果表明：CO在这种电极上的吸附方式同覆盖度有很大的关系；甲醇能在摘要Au以)re一Ptst，c:./GC电极一上发生自发解离吸附产生Co，这种铂包金电极对甲醇显示较好的电催化活性，有望在直接甲醇燃料电池（DMFC）中运用。以CO和SCN’作为探钊一分子研究了铂包金纳米粒子的SERS行为，发现这种纳米粒子铂壳的厚度对SERS行为有很大的影响，同时发现当电位变化时SCN一在铂包金纳米粒子土会出现S端和N端吸附方式的转换。 4.采用微波加热、乙二醇还原法，制备出了可控载铂量的纳米粒子负载的碳纳米管（Pt一CNT）。这种方法制备的Pt一CNT上铂具有非常好的分散性，负载的均匀度及载量是目前所报道的最好结果。研究表明:碳纳米管的处理时间及氯铂酸和碳纳米管的相对质量对合成Pt一CNT的微结构有重要的影响;这种方法还可以合成目前尚未见报道的‘铂纳米管’，也为其它金属纳米管的制备提供了一种新型的方法。CO在这种新型的铂纳米材料上除了有线性和桥式两种吸附方式外，首次发现 CO的第三种吸附方式。在Pt一CNT上还观察到了SCN一的S端吸附vc-N的SERS信号，这说明可用拉曼光一潜来表征CNT和Pt一CNT。这也为其它金属纳米粒子负载的cNT提供了一种新的检测方法。碳纳米管负载金属（特别是过渡金属）纳米粒子有可能成为一种新型的纳米级SERS基底，激起广大从事表面增强拉曼光谱的研究者新的热情。更多还原

【Abstract】 The main purpose of the present work is to investigate dissociative andadsorption of clhanol at roughcncn plalinm and Pt-Ru electrodes, to devise a simple and efficient measure to synthesize platinum-based nano-electrocatalysts and prepare the Pt-based nanoparticles modified GC electrode. The electro-catalytic behavior of some organic molecules such as formic acid, methanol and CO at these Pt-based electrodes was studied and Surface Enhanced Raman spectroscopy (SERS) was extended to investigate the electro-catalytic behavior of organic small molecules on Pt-based nanoparticles supported GC surface. Their structure, size, optical and electronic properties were systematically characterized and estimated by TEM, XRD, SAED, UV-Visible, AFM. These electro-catalytic and SERS behaviors of organic small molecules was investigated by combining conventional electrochemical methods with Surface Enhanced Raman spectroscopy (SERS). The thesis mainly consists of the following four parts:1. The behaviors of adsorption and oxidation of ethanol on a roughening platinum electrode with high activity of SERS were studied by using cyclic voltammetry and in-situ surface enhanced Raman spectroscopy because of the key roles of in the direct alcohol fuel cell (DAFC). The effect of the roughened factor, the initial concentration of ethanol, the electrode potential on dissociative adsorption of ethanol in an acid solution were systematically discussed by carefully designing potential programme. Assisted by the highly sensitive confocal microprobe Raman spectrometer and proper surface roughening procedure, surface Raman spectra of dissociative adsorption of ethanol on Pt electrode were obtained for the first. The investigation also shows that pH and electrolytes have a marked influence on the dissociative adsorption of ethanol on the roughening platinum surface. It were firstly found that ethanol can be self-dissociated to produce poisoning intermediate CO at least, which discourage the further oxidation of ethanol, some information of Pt-C and Pt-C-Pt stretching vibration from linearly -adsorbed and bridged-adsorbed CO located in low frequency were examined, respectively. The investigation also shows that the electro-oxidationof ethanol on the roughened platinum was a diffuse-controlled reaction in sulfuric acid. The interesting conversion of bridged adsorbed CO to linearly-bonded CO from dissociation of ethanol was also observed in a base medium when the electrode potential was changed. By correlating the in-situ SERS date with the electrochemical dates, it was found that the oxidation of ethanol was processed via the parallel mechanism. It is especially noticed that this part also extends SERS to the electrocatalytic fields of C2 organic molecules.2. Two different kinds of Pt-Ru electrode were prepared by depositing Ru on the roughened Pt electrode surface and co-depositing Pt and Ru at the smooth glassy carbon (GC) electrode, respectively. The SERs of ethanol and formic acid at the roughened Pt-Ru electrode were firstly obtained for the first time. The result showed that the presence of Ru could enhance the electro-catalytic activities in electrooxidation of ethanol and formic acid. The coverage of Ru was concisely discussed by using CV, I-t curves and SERS. The presence of Ru-O peaks of CV in sulfuric acid and Raman spectra at -600 cm-1 help to argue for the bi-function mechanism. The observations of signals of strongly adsorbed CO and active intermediates located at -1380 cm-1 from HCOOH electrooxidation further to confirm that the oxidation of formic acid on Pt-Ru/GC was processed via the parallel mechanism.3. Aucore-Ptshell nanoparticles with well-dispersed and controllable size (20-150 nm) were synthesized by using a seed-induced approach, and these nanoparticles were also assembled on GC electrode surface to fabricate Aucore-Ptshell/GC electrode whose electrochemical behavior was similar to that of the roughened Pt electrode. The results shows that the ways of CO adsorbed on Aucore-Ptshell/G更多还原