Synthesis and characterization of high surface area three dimensional mesoporous electrodes.

摘要

Mesoporous materials are defined as materials with pore diameters in the range of 2-50 nanometers. These materials are most commonly formed by templating with self-assembled surfactants. The work presented here has demonstrated the successful templating of both mesoporous silica and mesoporous metal films using block copolymers. This technique has been applied to films grown on both planar and three dimensional electrodes in order to produce high surface area porous electrodes.;Mesoporous metal films have been produced via direct templating using Pluronic block copolymers. This technique consists of electrodepositing the templated metal film from a mixture containing approximately equal parts of a templating polymer and an aqueous plating solution. Such films have been produced on both planar gold electrodes and three dimensional foamed nickel electrodes. This technique has resulted in a 35-fold increase in surface area of a foamed nickel electrode, although micro X-ray fluorescence indicates that the coverage of the film can be variable.;Metal nanowire films have been produced via indirect templating. This method consisted of using a polymer-templated mesoporous silica film to template the electrodeposition of the metal nanowire film. This method has successfully produced surface area enhancing films on both planar and three dimensional electrodes. While ordered nanowire films were grown on planar substrates, a disordered network was created when using foamed nickel substrates. The disordered metal nanowire films have resulted in a 120-fold increase in the surface area of foamed nickel electrodes. Micro X-ray fluorescence indicates that film coverage is reasonably even, with a slight increase in coverage at the edges of the electrode.;Periodic mesoporous silica films have been examined on different metal substrates to determine the variation in porous structure using grazing incidence small-angle X-ray scattering (GISAXS). This examination has shown that the periodicity of the mesoporous silica film, particularly perpendicular to the substrate surface changes as a function of the metal substrate. This change in periodicity was found to correlate to the standard reduction potential of the metal. This has been attributed to the presence of metal ions within the silica structure of the mesoporous films.