【作者】 周志有；

【导师】 孙世刚；

【作者基本信息】 厦门大学 ， 物理化学， 2004， 博士

【摘要】 固液界面电化学原位红外反射光谱利用指纹特征和表面选律，检测电极表面吸附物种及其成键和取向，在分子水平上研究反应机理。时间分辨和空间分辨是原位红外光谱两个重要的发展方向。其中时间分辨光谱，在检测短寿命中间体，跟踪反应历程，获取分子水平层次的动力学规律等方面可提供独到的信息。 本论文自行设计并研制信号同步仪，采用微电极并与红外显微镜相结合，建立了外反射型电化学原位步进扫描时间分辨显微FTIR光谱（in situSSTR-MFTIRS），光谱的时间分辨率最快可达10μs。利用纳米结构电极的异常红外效应，显著提高光谱检测灵敏度，克服了通常薄层电解池中电极对电位变化响应慢的不足，拓宽了快速时间分辨红外光谱的应用范围，为研究电化学快速反应动力学和表面动态过程奠定了基础，开展了以下研究：（1） 运用SSTR-MFTIRS研究了纳米结构Pt微电极上桥式吸附态CO向线型吸附态CO转化的动态过程，观察到转化中间态CO，初步提出转化过程的模型并获得定量的转化动力学数据。（2）设计并研制具有快速传质能力的流动电解池和微电极，实现了将SSTR-MFTIRS应用于不可逆电化学反应过程中的研究，发现纳米结构Pt微电极上吸附态CO的不可逆氧化经历“成核—成长”机理。（3）运用SSTR-MFTIRS研究了纳米结构Pt微电极上吸附态SCN^-的电位诱导取向转化动力学，发现SCN^-从S端吸附转为N端吸附的速度明显低于其逆过程。 此外还通过编制EG&G263型恒电位仪与红外光谱仪的同步控制软件，建立了电化学原位快速扫描时间分辨显微FTIR反射光谱（RSTR-FTIRS），实现循环伏安和红外光谱同时快速采集，在200mVs^-1电位扫描下，光谱的电位分辨率仍可达2.6mV，获得碱性介质中甲醇电催化氧化动态过程的新信息。 本论文建立的两种原位快速时间分辨显微FTIR反射光谱，实质性地发展了外反射型电化学原位红外光谱技术，所获得的纳米结构微电极表面动态过程和反应动力学研究结果对于深入认识分子水平上的电极过程动力学规律、发展电催化及相关理论具有重要意义。更多还原

【Abstract】 Electrochemical in situ infrared reflection spectroscopy, on the basis of its fingerprint and surface selection rules, can identify the nature of adsorbates and their surface bonding and orientation in electrode/electrolyte interfaces. The time-resolved and space-resolved spectroscopy have become currently two main directions of the development of electrochemical in situ IR spectroscopy. The former is unique in probing short lifetime intermediates, tracking reaction processes and providing dynamic information at molecule level in electrochemistry.In this thesis, we have established an electrochemical in situ step-scan time-resolved microscope FTIR external reflection spectroscopy (in situ SSTR-MFTIRS). The setup consists of an infrared microscope working with microelectrodes, and a home-designed and fabricated signal synchronizer. The time resolution of in situ spectra can reach up to 10s. Abnormal infrared effects (AIREs) of the nanostructured Pt microelectrode was used to improve significantly the IR determination sensitivity. The fast time-resolved FTIRS carried out in a thin-layer IR cell extended the possibility of using in situ SSTR-MFTIRS to study a wide variety of electrochemical reactions. It has been demonstrated that the SSTR-MFTIRS is a promising tool to be used in studies of kinetics and surface processes of fast reactions.The studies include: (1) the dynamic processes of site conversion between bridge bonded CO (COB) and linear bonded CO (COO on a nanostructured Pt microelectrode. Based on the determination of intermediate CO species in the site conversion processes and the acquisition of quantitative data of concerning the kinetics, a model of site conversion of adsorbed CO was suggested; (2) A novel spectroelectrochemical flow cell and a microelectrode possessing fastmass transfer were specially designed and fabricated, which allow irreversible electrochemical reactions to be studied by SSTR-MFTIRS. It has illustrated that the irreversible oxidation of CO adsorbed on nanostructured Pt microelectrode occurred according a nucleation and growth mechanism; (3) The potential induced orientation conversion of SCN" adsorbed on nanostructured Pt microelectrode was also investigated by using the SSTR-MFTIRS. It was found that the conversion rate from S-bonded SCN" to N-bonded SCN" is considerably slower than that of the reverse reaction.Through a home-developed software to realize the synchronization between 263A potentiostat (EG&G) and FTIR spectrometer, we have developed an electrochemical in situ rapid-scan time-resolved microscope FTIR reflection spectroscopy (RSTR-FTIRS), by which the collection of infrared spectra with an interval 2.6mV and the acquisition of cyclic voltammograms at a scan rate as large as 200mVs-1 can be done simultaneously. By using the RSTR-FTIRS, new information on the kinetics of methanol electrocatalytic oxidation in alkaline media was obtained.The establishment of the two types of electrochemical in situ fast time-resolved microscope FTIR reflection spectroscopy have progressed substantially the technique of electrochemical in situ external reflection infrared spectroscopy. The results concerning surface dynamic processes and kinetics obtaining in the present study have thrown a light in understanding at the molecular level the principle of electrode kinetics, and to develop the theory of electrocatalysis and relevant disciplines.更多还原