Multi-Walled Carbon Nanotubes Decorated with Silver Nanoparticles for Acetone Gas Sensing at Room Temperature

Multi-walled carbon nanotubes (MWCNTs) without and with adsorbed silver nanoparticles (Ag-NPs), are used to detect acetone vapour. MWCNTs are grown on SiO₂/Si substrates and silver (Ag) nanoparticles (NPs) are deposited onto some of these MWCNTs using electron beam evaporation method. The sensitivity of CNT based sensors (with and without NPs) increases with the concentration of acetone vapour (50 ppm to 800 ppm) while a substantial rise in sensitivity is obtained from MWCNTs with Ag NPs. Band diagrams of the MWCNTs, with and without NPs, are analyzed to understand the gas molecules adsorption phenomena. This study is the first to establish that such sensors can operate at 27 °C rather than the 180 °C–450 °C used elsewhere, thus offering significant advantages over existing methods. To investigate the sensors’ dependability, they’re exposed to three cycles of 50 ppm acetone gas. These tests show that the devices’ responses remain unchanged, indicating their reliability. The effects of humidity upon MWCNT acetone sensors within 100 ppm of acetone vapour are also studied and improved performance towards stability and response/recovery is observed for the sensors with Ag-NPs. Furthermore, higher selectivity is observed for the Ag-coated sensors for acetone against various target gases (acetone, ethanol, NO₂, ammonia, and acetone with water).