The synthesis and characterization of zeolite films on tin oxide coated glass electrodes

This thesis describes an investigation into the growth of zeolite films on tin oxide coated glass electrodes and their subsequent characterization by XRD and SEM. Furthermore, electrochemical methods are developed to determine the presence or absence of defects in the zeolite films. Probe molecules are used to show that the sieving properties of the zeolite films can influence the electrochemistry of redox active species.; Zeolite A and Y films were fabricated using the 'seed and feed' method in which small zeolites were attached to the surface of the electrode through the use of a cationic polymer. Through secondary growth, these 'seeds' were grown hydrothermally into coherent films. The films were characterized via X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and interference microscopy (IM). These techniques revealed information such as crystal size, zeolite phase identification and some information on film orientation. IM was used to determine the thickness of the Zeolite A films.; Most films reported in the literature have been characterized via SEM. But this method fails to easily detect micron sized defects. In our lab, an electrochemical means has been devised to determine the presence or absence of defects within the film. Charge exclusion studies were undertaken with potassium ferricyanide to probe for defects or cracks in the film. Since ferricyanide is negatively charged, it cannot enter the pores of the zeolite to access the electrode solution interface. Similar experiments were performed for a size excluded cation ruthenium tris-bipyridine. Copper cations (charge and size included) were used to determine that copper was diffusing through the pores of the zeolite film.; Oxygen reduction studies were undertaken to determine if neutral species can diffuse through the zeolite pore system. Based on chronocoulometry and cyclic voltammetry with different forms of zeolite A films, it was determined that oxygen diffuses through the zeolite pores in the film to access the electrode solution interface.