Metal loaded nano-carbon gas sensor array for pollutant detection *

Many research works report a sensitive detection of a wide variety of gas species. However, their in-lab detection is usually performed by using single gases and, therefore, selectivity often remains an unsolved issue. This paper reports a four-sensor array employing different nano-carbon sensitive layers (bare graphene, SnO2@Graphene, WO3@Graphene, and Au@CNTs). The different gas-sensitive films were characterised via several techniques such as FESEM, TEM, and Raman. First, an extensive study was performed to detect isolated NO2, CO2, and NH3 molecules, unravelling the sensing mechanism at the operating temperatures applied. Besides, the effect of the ambient moisture was also evaluated. Afterwards, a model for target gas identification and concentration prediction was developed. Indeed, the sensor array was used in mixtures of NO2 and CO2 for studying the cross-sensitivity and developing a calibration model. As a result, the NO2 detection with different background levels of CO2 was achieved with an R (2) of 0.987 and an RMSE of about 22 ppb.