The sensing behaviour of metal oxides (ZnO, CuO and Sm2O3) doped-SnO2 for detection of low concentrations of chlorinated volatile organic compounds

A SnO2-based semiconductor thick film gas sensor was fabricated for detection of chlorinated volatile organic compounds (VOCs) such as dichloromethane (DCM), trichloroethylene (TCE) and 2-chloroethylethylsulfide (CEES) at concentrations of 10, 20 and 10 ppm respectively with temperatures ranging from 100 to 400 °C. Other semiconductors such as ZnO, CuO in 5.0 wt% and Sm2O3 in 1.0, 5.0 and 10.0 wt% were added to SnO2 by a co-precipitation method. The samples were characterized by TEM, XRD and BET. The characterization results showed that presence of dopants causes an increase in surface area and a decrease in particle size of the sensing materials. It was found that SnO2–5.0 wt% Sm2O3 has the highest response to DCM and CEES, specially at low temperatures. Also the response was quite high for this sensor even at a concentration as low as 0.1 ppm. However, presence of the promoters suppressed the sensitivity to TCE.