(304f) Synthesis of Metallic Nanostructures Using Mesoporous Templates and Supercritical CO2 as Reaction Medium

The synthesis of metallic nanostructures has been, in the current decade, vastly investigated due to its extraordinary properties exerted at such small scales. These nanostructures can be used in many different industries including electronic, photonics and act as building blocks for future nanodevices. These techniques are developed to produce nanostructures suited to perform tasks according to the properties they possess at a particular scale range. One method developed to guarantee nanowire diameter is by using templates to mold out the necessary nanostructures. The chemical fluid deposition (CFD) process involves a metal precursor be dissolved in supercritical fluid and then reduced to deposit metal particles in the porous channels of the selected template.

Platinum nanostructures have been fabricated by CFD method using supercritical carbon dioxide (CO₂) as the reaction medium. Ordered platinum nanowires were molded out from a mesoporous silica template, SBA-15, with a pore channel diameter of 7 nm. Solubility study of the platinum precursor, platinum(II) dimethylcyclooctadiene, in the supercritical CO₂ was first carried out to obtain a phase diagram in order to optimize the operating parameters required to enhance the infiltration of metal precursor into the porous channels prior to the deposition process. High purity and uniform nanowire bundles resulted after template removal with large aspect ratio of 200:1 carried out at moderate operating temperatures and pressures.