Mass transport and electrode accessibility through periodic self-assembled nanoporous silica thin films.

Ordered nanoporous silica films have attracted great interest for their potential use to template nanowires for photovoltaics and thermoelectrics. However, it is crucial to develop films such that an electrode under the nanoporous film is accessible to solution species via facile mass transport through well-defined pores. Here, we quantitatively measure the electrode accessibility and the effective species diffusivity for nearly all the known nanoporous silica film structures formed by evaporation-induced self-assembly upon dip-coating or spin-coating.

Ion transport in the microporous titanosilicate ETS-10.

Impedance spectroscopy was used to investigate ion transport in the microporous crystalline framework titanosilicate ETS-10 in the frequency range from 1 Hz to 10 MHz. These data were compared to measured data from the microporous aluminosilicate zeolite X. Na-ETS-10 was found to have a lower activation energy for ion conduction than that of NaX, 58.

Simulation and interpretation of 2D diffraction patterns from self-assembled nanostructured films at arbitrary angles of incidence: from grazing incidence (above the critical angle) to transmission perpendicular to the substrate.

A method to calculate the location of all Bragg diffraction peaks from nanostructured thin films for arbitrary angles of incidence from just above the critical angle to transmission perpendicular to the film is reported. At grazing angles, the positions are calculated using the distorted wave Born approximation (DWBA), whereas for larger angles where the diffracted beams are transmitted though the substrate, the Born approximation (BA) is used. This method has been incorporated into simulation code (called NANOCELL) and may be used to overlay simulated spot patterns directly onto two-dimensional (2D) grazing angle of incidence small-angle X-ray scattering (GISAXS) patterns and 2D SAXS patterns.

Versatile fabrication of distorted cubic mesoporous silica film using CTAB together with a hydrophobic organic additive.

We have succeeded in the fabrication of distorted cubic R-3m mesoporous silica film with 3D open mesostructure providing high pore accessibility from the surface-air interface of the film. The film fabrication involves a unique approach of adding 1,3,5- triisopropylbenzene (TIPB) to the silica/cetyltrimethylammoniumbromide (CTAB) coating sol during its preparation. The addition of TIPB induces the formation of spheroid micelles, promoting R-3m mesostructure in the film.