(220f) Vesicle Templating of Hollow Oxide Nanoparticles

This research focuses on the development of facile scalable methods for the fabrication of porous hollow inorganic spheres using equilibrium catanionic vesicles as templates. Hollow inorganic nanospheres exhibit catalytic activities and properties from their solid counterparts with the advantages of high surface area and low density. As part of the overall project we have studied how to control size and shell thickness of the inorganic hollow particle. In effect, the structure depends on two length scales that are decoupled from each other. The first scale determines the diameter of the spheres, which is in the range of 50 to 200 nm and can be tuned by controlling the size of the templating vesicle and the second length scale determines the thickness of the inorganic deposited layer. The vesicle size is tuned by the composition ratio of the two surfactants Cetyltrimethylammonium Bromide (CTAB) and Sodium Perfluorooctanate (FC7) and characterized by using Cryo-Transmission Electron Microscopy (Cryo-TEM), Small Angle Neutron Scattering (SANS), and Dynamic Light Scattering. The inorganic shell's thickness was controlled by the vesicle's concentration in the solution versus precursor's concentration, and solution properties as pH and temperature. Multiple inorganic layers were fabricated by surface functionalization of the previous inorganic deposition on the vesicular template. Inorganic shells were characterized with Cryogenic Transmission Electron Microscopy (Cryo-TEM), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS)