Green synthesis, characterization of SnO2 3D microbars with surface 2D nanostructures and evaluation of electrical properties of PMMA-SnO2 hybrid nanocomposites

Abstract

SnO2 3D microbars (L ∼ 10 µm × B ∼ 1 µm x T ∼ 1 µm) distributed with 2D nanostructures (D ∼ 20 - 50 nm x l ∼ few nm) were synthesized by green approach using Plectranthus amboinicus plant extract. Effect of calcination treatments on the morphological changes of both primary microbars and secondary nanostructures were investigated. Dense corrugated networks of secondary particles were observed in the freshly synthesized material. When subjected to a temperature of 200 °C the densely covered particles on the surface, separate to distinct nanostructures. On further rise of temperature up to 400 °C, nanostructure networks break to complete individual nanoparticles, along with mild fragmental damage of particles. Presence of functional groups and bandgap energy levels of 3D/2D SnO2 material was studied using Fourier Transform Infra-Red (FTIR) and UV-Visible (UV-Vis) spectroscopy, respectively. Bandgap energy level of 3.05 eV was observed at 400 °C and 3.06 eV was observed at other two conditions. Structural, morphological and elemental characterization of the material was studied by X-ray diffraction (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray Analysis (EDAX) spectroscopy. Using Polymethyl methacrylate (PMMA) as matrix and 3D/2D SnO2 as the dispersed filler phase nanocomposite films were prepared. Effect of 3D/2D SnO2 loading on the alternating current (AC) conductivity of the nanocomposite films was investigated. Effect of frequency on AC conductivity, permittivity and loss factor of the composites were reported. The composites exhibited frequency dependent conductivity at lower frequencies and frequency independent conductivity at higher frequencies.