The formation of layers of porous crystalline tin dioxide from a composite on the basis of multiwalled carbon-nanotube arrays

Abstract

A new method for the synthesis of porous crystalline tin-dioxide (SnO₂) layers from composites on the basis of multiwalled carbon nanotubes (MWCNTs) and nonstoichiometric amorphous tin oxide (MWCNT/SnO_x) is proposed. An MWCN/SnO_x composite layer produced by magnetron sputtering is annealed in air atmosphere at 500°C for 30 min. A homogeneous porous layer comprised of crystalline SnO₂ spherical particles with a size of about 0.1 μm is obtained as a result. In the process of annealing, nearly all the amount of carbon is removed in the form of gaseous oxides (only a small amount remains in the upper part of the porous SnO₂ layer). The structural defectiveness of nanotube walls, which increases because of the magnetron deposition of tin, plays a crucial role in the carbon oxidation and destruction of MWCNTs.