ZnO nanowires based e-nose for the detection of H2S and NO2 toxic gases

In this work, a novel ZnO NWs based e-nose has been developed and demonstrated successfully for its ability to discriminate H2S and NO2 test gases. For this, a MS was fabricated by modifying the surface of the ZnO NWs with suitable sensitizers (∼<10 nm) namely Ni, Au, Cu, and MgO. A post deposition annealing in oxygen environment results in the formation of ZnO–CuO, ZnO–Au, ZnO–NiO and ZnO–MgO heterojunctions. The data repository was formed by measuring the response curves for different set of gas, concentration and operating temperature. The gas sensing results were subsequently interpreted employing both graphical analysis (3D bar chart) and multivariate data analysis (principal component analysis) techniques. For better understanding, the steps involved in the PCA have been explained and discussed elaborately. Our result indicate that the e-nose is capable for producing the qualitative as well as quantitative discrimination of two test gases namely H2S and NO2.