Application of candle soot CNPs-TiO₂-PVP composite in the detection of volatile organic compounds with aldehyde, amine and ketone functional groups by resistance and impedance responses

We have fabricated a solid-state gas sensor using a composite sensor layer made up of three different sensing materials namely; candle soot Carbon nanoparticles, Titanium dioxide and Poly (vinyl) pyrrolidone (PVP). The study was carried out to study the sensor's response towards butyraldehyde, diethylamine and isobutyrophenone vapour at room temperature. The sensor was prepared by mixing candle soot CNPs, TiO2 and PVP in dimethylformamide using the ratio (2:1:3) respectively. The sensing materials were characterised using Brunauer-Emmett-Teller (BET), x-ray diffraction (XRD), Transmission and Scanning Electron Microscopy (TEM, SEM). The sensor's response was measured by injecting a volume of 1 to 5 μl of each liquid analyte in a round-bottomed glass and an LCR metre was used to measure the R and Z responses. In both parameters, the sensor responded well to the different analytes, the response of the sensor linearly increases as the analyte vapour concentration increases. The sensors were discovered to exhibit more sensitivity of 0.07 ω ppm-1 towards diethylamine in R response and it was more sensitive towards isobutyrophenone in Z response giving a sensitivity of 0.14 ω ppm-1 while Butyraldehyde had the fastest response time of 145 s and Diethylamine had the fasted recovery time 130 s.