Pristine SnO2 and SnO2/rGO nanocomposites: Synthesis, microstructural, optical and electrical characteristics for potential sensing applications

Metal oxide n-type SnO2 nanoparticles synthesized via sol-gel method. Different weight percentages (5 %, 10 %, 15 %, and 20 %) of p-type reduced graphene oxide (rGO) were loaded on SnO2 nanoparticles via sonication process. The effect of varied composition of rGO on SnO2/rGO nanocomposite investigated using structure, morphology, composition, optical and electrical characteristics. The structural analysis from XRD showed deviations in the peak position corresponding to SnO2 nanoparticles. These deviations were evaluated from crystallite size, unit cell parameters, volume, and strain confirm the formation of SnO2/rGO nanocomposite. BF-TEM images showed formation of polyhedral SnO2 nanoparticles and SnO2/rGO composite of varied particle sizes. FTIR spectra confirms the presence of C--O and C-O which exhibits reduction to graphene oxide. Raman spectra showed deviations in the disordered band (1365 to 1374 cm-1) and graphitic band (1580 to 1598 cm-1) of rGO on composite formation. Such deviations in the XRD, Raman and bandgap confirms the co-ordination of rGO with SnO2. The electrical conductance and heterojunction parameters were calculated using I-V measurements. The results showed improved electrical conductivity, heterojunction parameters and availability of higher active sites that promote the use of SnO2/rGO nanocomposites for possible application in room temperature gas sensors.