Graphene-Based Nanocomposite Containing Bismuth-Tin Oxide for Increasing the Efficiency of Carbon-Monoxide Sensors

Graphene materials are extensively studied for producing gas sensors due to their thin two-dimensional conjugated structures at the atomic level, as well as their high conductivity and significant specific surface areas. In this study on a graphene-based sensor, we combined graphene Oxide (GO) with Carbon Nanotubes (CNT), Bismuth (Bi), and Tin (Sn) nanoparticles to enhance the sensing properties. GO was synthesized using the modified Hummer’s method, while Tin and Bismuth nanoparticles were produced through a combination of Microwave/Sono-chemistry methods. The samples were characterised through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet spectroscopy (UV-vis). The analyses showed that the nanoparticles were successfully placed in the nano-meter phase. From XRD analysis the average crystal size of nanoparticles and nanocomposites were calculated between 23 nm and 45 nm. The average particle size according to SEM analyses for all synthesized materials is not less than 10 nm and not more than 30 nm and the samples were free of lumps. Four graphene-based sensors namely GO, GO/CNT/SnO₂, GO/CNT/Bi₂O₃, and GO/CNT/Bi₂O₃/SnO₂ were fabricated and subjected to a sensor test in the presence of Carbon Monoxide (CO) gas. Our experimental results showed that incorporating CNT, SnO₂, and Bi₂O₃ into GO enhanced the sensor performance which resulted in shorter response/recovery times, 4/42 s for GO/CNT/Bi₂O₃/SnO₂ in contrast to 8/50 s for pure GO. Given the findings of this study, the proposed sensor, with its affordable cost, straightforward fabrication process, and superior sensing capabilities, appears to be a promising solution for real-time CO monitoring.