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The Oxidation Behavior and Raman Study of C1 Organic Molecules on Pt-based Electrodes

Author: WangXiaoCong
Tutor: ZhongQiLing；RenBin
School: Jiangxi Normal University
Course: Organic Chemistry
Keywords: Oxidation Behavior Spectroscopic Study Electrocatalysis Situ Raman spectroscopy Adsorption and Oxidation Platinum oxide High roughness Platinum electrode Reactive intermediates Formic acid formaldehyde
CLC: O646
Type: Master's thesis
Year: 2002
Downloads: 104
Quote: 2
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Abstract


Oxidation of small organic molecules not only can be used as a direct fuel cell anode process electrocatalytic basic research important issue. Methanol formic acid formaldehyde containing only one carbon atom, the molecular structure is simple, in-depth study in the electrocatalytic oxidation of a transition metal having a significant application background platinum reality application process is not only guiding values, but at the molecular level understanding of complex molecules electrocatalytic The reaction mechanism is of great significance. It has long been in the small organic molecules (especially C 1 molecules such as CH 3 OH, HCHO and HCOOH, etc.) on the transition metal adsorption and reaction of important research areas a large number of productive work. However, each research team used electrode materials, pretreatment methods, solution composition as well as the means of detection, but also because of the various research studies the complexity of the system and the limit of detection technology, to date details of their specific reaction inconclusive, some important issues remain to be resolved, the example, the adsorption characteristics under the reaction conditions, and the role played in the reaction (toxic intermediates or reactive intermediates), the surface structure and the roughness of the special effects. The study of small organic molecules adsorption and reaction of the various means of infrared spectroscopy is the most widely applied a field spectroscopy techniques, and made a significant contribution to a better understanding of this area. But the electrodes used in the infrared spectrum is usually single crystal, smoothness and low surface roughness of the electrode, with the practical application of the higher roughness of the electrode have a greater difference. The SERS of pair of electrodes typically require a certain degree of roughness and can compensate for the lack of infrared technology, so in this respect, while SERS vibration information of metals and adsorption of the low frequency region can be obtained, and this is difficult for infrared technology to be done. However, decades SERS application limitations of Ag, Au, and Cu electrode. Currently, in addition to the work of the research team of Xiamen University Tanaka group, still no other relevant C 1 organic molecules on the pure transition metal electrodes Raman spectroscopy. In this thesis work from starting to broaden the SERS of C adsorption of organic molecules on transition metal platinum and reaction purposes, mainly to carry out a study of the following aspects: (1) to proceed from the preparation of the platinum electrode improvement and innovation to obtain high SERS activity of the platinum electrode surface rough method, in order to select a suitable electrode surface the need for different research purposes. Based on the preparation method on the basis of using the the SERS technology field study preparation of a variety of platinum oxide reduction process, thus further probing of platinum oxide electro-oxidation of small organic molecules. Successfully prepared CPRPt CCRPt, CCRRPt PtD (Pt) the four nano pure platinum electrode surface, and compare their performance. Found that the average activity of the CCRPt electrocatalytic oxidation of methanol, pyridine adsorption SERS activity the highest; the high roughness CPRPt electrode C 1 adsorption of organic molecules oxidation of SERS favor; while the the almost smooth CCRRPt electrode surface not only electricity Catalytic oxidation activity doubled, and strong SERS spectra of pyridine adsorption. Successfully prepared a series of electrodes with different features on the molecular level table (sector) the surface electrochemistry will play an important role. While $ z, millet using in situ Raman spectroscopy to study the different media, different methods of circulating redox platinum oxide reduction process (ORC) process, which peroxide and superoxide disappear in potential at 0. The ZV about lattice oxide and platinum oxide disappear in the 0 V and -0.25 V, respectively. Preliminary study of the impact of different reduction potential of the platinum electrode surface nanoparticles for methanol electro-catalytic activity noon. (2) the use of SERS technology combined with cyclic voltammetry study C; dissociative adsorption of organic molecules on roughened platinum electrode closer to the actual methanol fuel cell behavior. Special attention to get people in the past have not yet obtained the electrode surface - Pt {vibration information adsorbed species interactions, and pay attention to the impact of the electrode potential on the adsorption and dissociation process. At the same time, focusing explore CI organic molecules adsorbed oxidation product in addition to CO outside. The main results are: a. Succeeded in demonstrating the molecular level CPRPt electrode formic acid and formaldehyde spontaneous dissociation, get strong single-ended low frequency region, dissociative adsorption of intermediate CO adsorption Pt {vibration peaks (about 490cm ') and bridge adsorption Pt {vibration peak (approximately 410cm '), the adsorption mode and the vibration mode corresponds to show that the importance of the guide to the signal of the low frequency region. b, for the first time the use of Raman spectroscopy detected HCOOH addition to CO oxidation product (reactive intermediates C00H, and the final product CO ;) powerful spectroscopic evidence for the dual path mechanism. (3) nano platinum the electrode particles modified polyaniline film PAn (Pt), can improve electrode performance, enhanced electrode catalytic activity, is expected to become more ideal electrode in the methanol fuel cell. For this reason, in the improved preparation method on the basis of our situ Raman spectroscopy to obtain a more detailed structure of polyaniline film with the potential to change the information, and then study the nano platinum particles CI small organic molecules adsorbed on the oxidation behavior of modified electrode . The results show that, PtAn (Pt) electrode catalytic activity than the of PTd (Pt) to be approximately 2.5 times higher. The electrode CI small organic molecules adsorbed on the oxidation behavior of Raman spectroscopy results proven to reduce catalyst poisoning. To sum up, we take advantage of the SERS technology in the detection of the advantages of high roughness of the surface of the low frequency region, information and research, as well as the advantages of three-dimensional space-resolved confocal Raman microscopy system has successfully applied closer to the actual methanol fuel cell high roughness of Pt metal and Pt particles the modified electrode * adsorption and oxidation reactions of organic molecules. Concluded due to the limited time of the thesis work is still incomplete, the system has yet to be in-depth study. However, these preliminary results showing the potential and prospects of the SERS technology applied to the actual electrode reaction system.

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