INDUSTRIAL APPLICATIONS OF TATIANA NANO PARTICLES

Industrial Applications of Tatiana Nano particles

Industrial Applications of Tatiana Nano particles

Introduction

Metal/semiconductor oxide composite Nano particles are extremely attractive because they exhibit novel optical, electrical, magnetic, and chemical properties that are not found in the individual components. The possible applications include nanoelectronics device, catalysis, nonlinear optical devices, etc. Titanium dioxide (TiO2) is one of the most widely studied semiconductor materials due to the wealth of useful applications. Recently, TiO2-based systems containing transition metal ions and noble metals have been investigated extensively to improve the efficiency of the photocatalytic and photoelectrochemical responses. Several routes to the fabrication of thin films containing Nano particles of semiconductors and metals have been suggested including physical techniques, chemical methods, or a two-step method consisting of Au(III)-complex chemisorption and subsequent photoreduction. Microstructured Au/TiO2 model catalysts are also produced by combining optical lithography methods for microstructuring with ultrahigh vacuum evaporation for Au nanoparticle deposition. In many applications, the ability to use nanoparticle properties for device fabrication will require the formation of highly ordered arrays of Nano particles. Several approaches have been reported to generate arrays of composite Nano particles. However, it is challenging to control the final morphology and composition of the produced nanostructures. There is still a strong demand for simple, facile routes to fabricate arrays of the metal/semiconductor composite nanostructures with different size, spacing or composition. The self-assembly of diblock copolymers has been recognized as an attractive platform toward highly ordered, periodic nanoscale structures. An increasing number of novel functional nanostructures have been reported from this unique class of polymers, for instance, magnetic storage media, resists in microelectronics, photonic band gap materials, planar optical waveguides, etc. In particular, it has also been shown that hexagonally ordered 2-dimensional (2D) arrays of metallic, inorganic, semiconductor, and metal/ semiconductor Nano particles could be generated using block copolymer as templates. Recently, thin films of amphiphilic poly(styrene-blockethylene oxide) copolymer (PS-b-PEO) with cylindrical PEO microdomains aligned perpendicular to the substrate surface have attracted increasing attention as scaffolds to produce arrays of inorganic nanostructures. Combining sol-gel (SG) process, organic-inorganic hybrid nanostructures can be fabricated with TiO2 selectively incorporated into the PEO microdomains. In this work, we extend this methodology to produce arrays of composite Au/TiO2 composite Nano particles using Au precursor-loaded block copolymer micelles as templates. Although sol-gel chemistry using block copolymers as structure-directing agent has been extensively exploited to generate highly ordered mesoporous materials, no experimental reports have yet been made concerning arrays of metal/ semiconductor composite Nano particles. The present approach involves the fabrication of organic-inorganic hybrid nanocomposite films with TiO2 and Au precursors incorporated into PEO mocrodomains. Specifically, we show that the lateral scale of the arrays of composite Nano particles, i.e., the size of each nanoparticle and spacing, as well as the composition can be finely tuned on the nanometer scale by controlling the relative amount of sol-gel precursor to block copolymer and the loading ratio of HAuCl4 to EO units in the block copolymer.

Experimental Part

Materials. Asymmetric poly(styrene-block-ethylene oxide) block copolymer (PS-b-PEO) with a polydispersity ...