Nanostructured Materials for Advanced Transportation Applications

Gold is known to be an inert metal. The oxide supported nanometer sized gold particles have been demonstrated recently to exhibit remarkable activity for few specific reactions like low temperature CO oxidation, reduction of Nitrogen oxides. The possibility of preparing nano-sized metal particles with homogeneous morphology and size is of great interest as these particles have extremely small size and a large specific surface area that can be used in a wide range of chemical and physical applications. Physicists predicted that the nanoparticles in the range of 1-10nm in diameter would display electronic structures, reflecting the electronic band structure of nanoparticles owing to quantum mechanical rules. As an effect larger variations are observed in the optical and electrical properties. The most famous example is the size tunable band gap of semiconductor nanocrystals. For the synthesis of composite materials, large specific area of the porous support material can be explored with respect to a wide range of chemical applications. The size distribution of the colloidal dispersion of solid particles is determined by the rate of nucleation of the solid cores and the subsequent growth. Catalytic activity depends upon the size and shape of nanoparticles. Mesoporous materials have large pores and high surface area thus provide good basis for catalysis, separations and sensors. From a catalytic point of view, inorganic nanoparticle mesopore composites have a potential to allow three dimensional designer catalysts with separate tuning of the microscopic catalytic rates on the nanoparticles surfaces as well as control over material transport by changes in the pore size. Synthesis of well dispersed metal particles inside a support material is of great interest and carries potential challenges. In this paper the authors present a technique of synthesis of the composite material using a self-assembly of mixed surfactant system. They form microstructures called reverse micelles. These micelles are formed in such a manner that the hydrophobic ends flock together in the interior of the sphere and the polar head groups are exposed to water. They can support the material synthesis by forming nanoreactors such that material synthesis within the micelles restricts the size of the material to the mesoscale level. They act as good templates for nanomaterial synthesis. These droplets are displaced randomly and subjected to Brownian motion wherein they exchange their water content and reform into two different micelles. Thus by the exchange the contents in each of the micelles interact with each other and give rise to different products on the nano-scale. Thus they form good templates for material synthesis.