Structure of composites based on multi-wall carbon nanotubes and tin oxide

The main purpose of this work was to study the structure, morphology, and composition of composites based on multi-walled carbon nanotubes (MWCNTs) and tin oxide obtained by the methods of chemical vapour deposition and magnetron sputtering. X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XANES), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) were used to analyse the structure and composition of the obtained composites. It is shown that the morphology and structure of the formed composites depend substantially on the change in the structure and chemical state of the outer walls of MWCNTs during the process of depositing tin oxide on their surface. It is established that when using the method of chemical vapour deposition, no signifi cant changes in the crystal structure and chemical state of carbon in the walls of the MWCNTs are observed. The MWCNTs surface weakly oxidises with the formation of carboxyl and carbonyl groups (C = O, COOH). As a result, tin oxide is distributed along the surface of the MWCNTs as separate clusters that interact weakly with the outer walls of carbon nanotubes. It is shown that tin oxide in clusters is mainly represented by defective crystalline SnO2. The magnetron sputtering method contributes to the formation of a large number of structural defects and a considerable oxidation of the MWCNTs surface with the formation of functional oxygen-containing groups of different composition (C-OH, C = O, COOH, C-O-C, -CO3, etc.). Signifi cant functionalization of the walls of carbon nanotubes leads to the chemical interaction between tin oxide and the surface of MWCNTs. This results in an increase in interracial adhesion in the composite, whereby the tin oxide uniformly covers the walls of the MWCNTs as a continuous layer. The obtained results can be used in the development of composites based on carbon nanotubes and metal oxides with the required structure and a set of physicochemical characteristics.