Carbon gas sensors synthesized using acacia auriculiformis tree branches to detect methanol, ethanol, acetone vapors and ammonia gas

Abstract

Metal oxides and carbon are the prime candidates of gas sensor devices. For the inaugural instance, carbonaceous particulate matter was meticulously derived from the branches of Acacia auriculiformis tree indigenous to Sri Lanka to detect vapor and gas. It is worth noting that biomass derived carbon had hitherto remain unexplored in the realm of vapor and gas detection. Carbon films were fabricated via the doctor blade method. The resistivity characteristic of these carbon samples exhibited discernible variations upon exposure to methanol, ethanol, acetone vapors, and ammonia gas. Notably, the gas-sensing properties of sample derived from the central core and the outer shell of Acacia auriculiformis tree branches were independently assessed in these vapors and gas at ambient temperature. Various analytical techniques, including X-ray diffraction (XRD), UVvisible absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), were judiciously employed to scrutinize the structural attribute, optical band gap, chemical composition and surface morphology of the aforementioned carbon film samples, respectively. XRD analyses unequivocally confirmed the successful formation of carbonaceous films. FTIR spectra conspicuously delineated the presence of oxygen within the carbon films. Importantly, the optical band gap of our carbon films manifested within the range characteristic of organic carbon. Furthermore, the resistance of the carbon films demonstrated a significant reduction upon adsorption of each vapor. It is noteworthy that while gas sensitivities and response times were superior for carbon derived from the central core of the Acacia tree branches, the recovery times were notably expedited for carbon synthesized from the outer shell of these branches. The zenith of gas sensitivity, an impressive 187%, was recorded in response to 1000 ppm of methanol vapor, when employing carbon sourced from the central core of the acacia tree branches.