Noble metal sensitized SnO2/RGO nanohybrids as chemiresistive E-nose for H2, H2S and NO2 detection

Hydrothermally synthesised noble metal (Pt, Pd) doped SnO2/RGO nanohybrids has been demonstrated first time for chemiresistive e-nose application towards the detection of H2, H2S and NO2 below their threshold limit values. More specifically, the multivariate statistical tools namely Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), and Hierarchical Cluster Analysis (HCA) have been employed effectively to achieve fruitful discrimination of H2, H2S, and NO2. The two-dimensional PCA studies reveals the discrimination between the three test-gases under observation with the variance of 59.16% and 40.84% for first and second principal components, respectively. Importantly, LDA has been demonstrated to be useful to classify the data with 76.39% accuracy. HCA dendrograms depicted into three different clusters indicates a significant discrimination of gases with 95.55% classification confidence. The adsorption studies along with the validity of the kinematical models indicated that SnO2/RGO and SnO2/RGO: Pt follows the pseudo second order equations for H2S and H2 adsorption respectively. On the contrary, SnO2/RGO: Pd obeys Ritchie equation for NO2 adsorption. In addition, the work function values for SnO2/RGO and SnO2/RGO: Pd were found decrease and increase by 153 and 135 meV, respectively upon exposure to H2S and NO2 gases. This clearly indicates the n-type nature of the synthesised nanohybrids.