Surfactant-mediated synthesis of functional metal oxide nanostructures via microwave irradiation-assisted chemical synth
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1174-V02-08
Surfactant-mediated synthesis of functional metal oxide nanostructures via microwave irradiation-assisted chemical synthesis Sanjaya Brahma1, S. A. Shivashankar1 Materials Research Centre, Indian Institute of Science, Bangalore-560012, India
ABSTRACT In the present work we report a rapid microwave irradiation-assisted chemical synthesis technique for the growth of nanoparticles, nanorods, and nanotubes of a variety of metal oxides in the presence of an appropriate surfactant (cationic, anionic, non ionic and polymeric), without the use of any templates. The method is simple, inexpensive, and helps one to prepare nanostructures in quick time, measured in seconds and minutes. This method has been applied successfully to synthesize nanostructures of a variety of binary and ternary metal oxides such as ZnO, CdO, Fe2O3, CuO, Ga2O3, Gd2O3, ZnFe2O4, etc. There is an observed variation in the morphology of the nanostructures with changes in different process parameters, such as microwave power, irradiation time, identity of solvent, type of surfactant, and its concentration.
INTRODUCTION With the advent of technologically sophisticated facilities, the synthesis strategies of metal oxide nanostructures, with potential application in many fields [1], have either been changed, or modified, and novel synthesis procedures undertaken by researchers. Recently developed synthesis techniques include the sol-gel technique [2], hydrothermal synthesis [3], solvothermal process [4], chemical co-precipitation [5], polyol synthesis, thermal decomposition [6] and spray pyrolysis [7]. While there has been a substantial improvement in these techniques, they are often energy-intensive and time-consuming. Thus, there has been a need to modify the existing synthesis techniques or to design a novel synthesis technique /procedure which consumes comparatively less time and energy, is less cumbersome, while requiring no expensive equipment. Microwave irradiation-assisted chemical synthesis [8-10] is such a process, and can be carried out in a simple “oven” at power varying from 160 – 800 W. In the present work, we have tried to explore the capability of this process in preparing different nanostructures of ZnO in particular and nanoparticles of other oxide materials such as CdO, Fe2O3, Ga2O3, Gd2O3, using the corresponding metal acetylacetonate complex, in presence of a surfactant. The as-prepared oxide materials either need a brief exposure to heat at a modest temperature to remove the surfactants or, no treatment at all, because they are already pure and crystalline. There is a discernible variation in the morphology of the nanostructures when different process parameters are changed, such as microwave power, irradiation time, identity of solvent, type of surfactant used and its concentration. Cationic, anionic, nonionic and polymeric surfactants have been used to generate a variety of nanostructures.
EXPERIMENTAL Metal oxide nanoparticles and nanostructures were prepared from the corresponding metal acetylacetonate, which is usu
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