Remarkable Electrical Conductivity Enhancement Through Mutual Variation of MWCNTs/Tin Oxide Concentration: Structural, Morphological and Electrical Properties

Tin oxide/MWCNTs hybrid nanocomposites were synthesized via the malic acid-assisted modified sol–gel method. Effect of the concentration variation of both MWCNTs and tin oxide on the hybrid nanostructure, morphology, thermal and optical properties was studied using spectroscopic and analytical tools including: thermal gravimetric analyses (TGA), x-ray diffraction (XRD), scanning electron microscope (SEM), transition electron microscope (TEM), and ultraviolet–visible (UV–Vis) spectroscopy. Thermal gravimetric analyses of the hybrid nanocomposites showed a mode of stability up ≈ 375°C, after this temperature the sample is subjected to decomposition of the MWCNTs. XRD patterns of the pristine tin oxide sample showed the presence of characteristic peaks related to two crystalline phases of tin oxide (rutile SnO2 and orthorhombic SnO), while the hybrid CSn10 (synthesized via 10% weight substitution of MWCNTs by tin oxide) and SnC10 (synthesized via 10% weight substitution of tin oxide by MWCNTs) nanocomposites showed a clear decrease in the crystallinity as a proof for dispersing of tin oxide nanoparticles within the hollow cavity of MWCNTs, which was further confirmed by SEM and TEM images. Furthermore, a complete absence of the characteristic peak of orthorhombic SnO was observed in the CSn10 sample. Optical and electrical properties of the hybrid nanocomposites-chitosan thin films were investigated before and after exposing to UV radiation for 1 h. The UV–Vis spectra showed a blue shift upon introducing MWCNTs into the oxide matrix while prolonged exposure to UV-radiation markedly affected the absorption and the band gaps of all nanocomposites. Investigation of the electric properties interestingly showed remarkable electrical conductivity enhancements upon introducing either MWCNTs or tin oxide in the matrix of each other. Introducing 10% MWCNTs into the tin oxide structure (SnC10) was accompanied by 76-fold increase in the electric conductivity; while incorporating 10% of tin oxide (CSn10) was accompanied by 110-fold increase in the electric conductivity of MWCNTs at 100 Hz frequency. Furthermore, the effect of prolonged UV-radiation on the electric properties of the synthesized hybrid nanocomposites was also reported.