| Platinum group metals and their alloys have been extensively employed in energy conversion and green synthesis as electrocatalysts owing to their high catalytic activity. Pt group metals at nanometer scale have attracted much attention worldwide because of their higher catalytic activity and better properties. It is well known that the properties of nanomaterials depend strongly on their nanostructures. Therefore, to understand the relationship between nanostructures and properties is of importance in exploring the origin of particular properties observed from nanometer-scale materials, and thereby in further improving or optimizing their properties. Our group has prepared nanometer-scale metal films in layer structures on glassy carbon (GC) substrate by cyclic voltammetric deposition. By using CO as probe molecule, we have revealed for the first time, Abnormal IR Effects (AIREs) on these layer nanostructured films. The AlREs consists of several abnormal IR features including the enhancement of IR absorption, the inversion of IR band direction (anti-absorption), and the increase of FWHM (increase of the number of different adsorption sites). The AIREs was conclusively demonstrated as a particular IR property exhibited commonly by nanostructured thin films of Pt group metals and their alloys. Further understanding of the relationship between AIREs and nanostructures is of significance in exploring the origin of AIREs, and in developing the principle and fundamental of IR reflectance spectroscopy, nanotechnology and nanoscience.In the present study, nanostructured island films were prepared by using different electrochemical methods on an individually addressable Pt microelectrode array (denoted as MEA1). These nanostructured films involved Pt microelectrode subjected to Fast Potential Cycles with Triangular Wave (FPCTW) for different times (r), Square Wave Oxidation and Reduction Cycles (SWORC) for different r, Cyclic Voltammetric (CV) deposition of platinum with different number of cycles (n), the sequential treatment of FPCTW for different rand CV deposition of platinum with n=10, CV deposition of Ruthenium with different n, CV deposition of Palladium with different ? CV deposition of Rhodium with different n. (abbreviated as PtME(T_t), PtME(S_t), Pt(n)/PtME, Pt(10)/PtME(T_t), Ru(n)/PtME, Pd(n)/PtME,Rh(n)/PtME, Rh(10)/PtME(T_@), respectively) A new surface combinatorial method has been developed by means of combining the MEA1 with an in situ microscope FTIR spectroscopy (in situ MFTIRS). Taken CO as probe molecule, we have systematically investigated the particular IR properties of nanostructured island films prepared in this work. The structure and electrochemical properties of these films were studied also by using CV, STM (Scanning Tunneling Microscope) and SEM (Scanning Electron Microscope) were also used to study systematically these films. The relationship between IR properties and nanostructures is discussed. It was demonstrated that the AIREs is closely related to structures of island films, but not to the substrate and the preparation methods. A particular IR feature (primarily denoted as Fano-like spectral feature) has been observed for the first time, when CO is adsorbed on island films of particular structure. It has also revealed a regular relationship between line shapes of COad bands in SPAFTIRS (or SNIFTIRS) and that in MSFTIRS. The results in this study have shown that the surface combinatorial method possesses advantages in remarkably economizing investigation time and in improving study efficiency. The results obtained in this thesis are of significance in exploring the intrinsic properties of low-dimensional nanostructured materials, and in developing fundamental of in situ FTIR reflection spectroscopy, and nanotechnology and nanoscience as well.The main results and conclusions are summarized as follows: 1. The Development of Surface Combinatorial Method.The individually addressable PtME array, i.e. MEA1, was designed and fabricated. The surface combinatorial studi... |
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