Preparation And Characterization Of Some Nano Composite Thin Films And Their Application Research

In this thesis, TiO2/GE, dendritic Ag/Cu and Pd/Ag nano composite thin films are prepared by electrochemical or electroless techniques. The morphology and composition of the films are studied comparatively by using XRD, SEM, AFM and XPS. Promising multifunctional applications are obtained including photocatalytic degradation, strong surface-enhanced Raman scattering (SERS) enhancement and superhydrophobic application. The main contents are described as follows:1. Nano-TiO2 particles were immobilized on graphite electrode (GE) and indium-tin oxide coated glass (ITO) using electrophoretic deposition, respectively. The obtained TiO2/GE and TiO2/ITO film electrodes were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and anodic photocurrent response test. It was found that TiO2/GE electrode had much higher photocurrent and more effectively reduced the recombination rate of the photo-induced electron-hole pairs, compared with TiO2/ITO electrode. The photocatalytic activity of TiO2/GE was higher than that of TiO/ITO for the photocatalytic degradation of acid red G.2. Formaldehyde was degradated with photo-catalysis by TiO2 nanoparticles and 2-methyl-2-nitro-propane (MNP) was used as a spin trap (ST). The radical intermediates in the process of reaction were studied and a new spin adducts (ST-R) was obtained. The results of Electron Paramagnetic resonance (EPR) indicated that intermediates of formaldehyde degradation in aqueous solution were·CH(OH)2. And a new degradation mechanism was proposed.3. Hierarchical and well-defined Ag dendrites were obtained by the reaction between copper microspheres electrodeposited on ITO and a solution of AgNO3. The composition, crystal structure and morphology of the deposits were characterized with XPS, EDX, XRD and SEM, respectively. The dendritic Ag/Cu film show significant SERS effect as probed with Rhodamine 6G (R6G). And also the surface of dendritic Ag/Cu film had a remarkable superhydrophobic property and low contact angle hysteresis after treatment with n-dodecanethiol.4. Pd/Ag films were electrolessly deposited onto p-silicon (100)-activated seed layers of Ag and Pd, respectively. The morphology and composition of the films were studied comparatively by using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Cathodic polarization curves for hydrogen evolution were recorded in 0.5mol/L H2SO4 without illumination. The experimental results showed that the film obtained on the Ag seed layer was rather a pure Ag film and not a Pd/Ag film, and also the Ag deposition rate on Pd sites was much faster than that on Ag sites.