Nanocomposites and nanomaterials

Directed synthesis tin (IV) oxide nanostructures
I.V. Bashmakov, S.V. Nahirniak, T.A. Dontsova
Department of Chemistry, National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Prospect Peremogy 37, Kiev-03056, Ukraine. 
E-mail: ivanbashmakov015@gmail,com

Tin (IV) oxide nanostructures are widely used in various industries: the photocatalysts production, solar cells and, in particular, for the gas sensors manufacture. In the latter case, the structural and sorption characteristics of the obtained nanopowders are the most important and can vary considerably depending on the synthesis method and the precursor’s type [1, 2]. Sol-gel and hydrothermal synthesis are the most promising methods for the creating of various structural and sorption characteristics of tin (IV) oxide. Consequently, to compare powders characteristics SnO2 samples were synthesized using these two ways in the aqueous agent. Characterization of SnO2 was carried out by diffraction methods and by the method of nitrogen sorption-desorption.
The results of diffraction studies indicate the formation of the pure cassiterite phase. Analysis of sorption isotherms for the Sample 1 obtained by sol-gel method indicates isotherm of IV type, and the Sample 2 synthesized by hydrothermal method characterized by I type isotherm. Thus, in the first case the mesoporous powder was obtained, in the second case the synthesized sample was microporous. Besides, the samples have also other difference. The values of the specific surface area of the Sample 1 and Sample 2 are 25 m2/g and 184 m2/g, respectively. This is due to the different general volumes and average pore radiuses corresponding to 0,031 cm3/g, 3,92 nm for Sample 1 and 0,185 cm3/g, 1,78 nm for Sample 2.
Therefore, the obtained data indicate significant differences in the structural and sorption characteristics of the tin (IV) oxide powders synthesized in various ways. The obtained results testify to the possibility of the directed synthesis of these powders. SnO2 samples for their usage as sensitive layers of gas sensors should have the largest possible surface area and to be micro-mesoporous with a predominant pore size in the range of 3-5 nm.

1.	Dontsova T.A. et al. Synthesis and characterization of titanium (IV) oxide from various precursors Springer Proceedings in Physics 2015, 183 : 331.
2.	Dontsova T.A., Nagirnyak S.V. et al. SnO2 Nanostructures: Effect of Processing Parameters on Their Structural and Functional Properties // Nanoscale Research Letters 2017, 12 : 332.