Improving the Selectivity of a Catalytic Film/Gas-Sensitive Film Laminated Metal Oxide Semiconductor Sensor for Mustard Using Temperature Dynamic Modulation

The poor selectivity of metal oxide semiconductor sensors is a major constraint to their application in the detection of chemical warfare agents. We prepared a (Pt+Pd+Rh)@Al2O3/(Pt+Rh)-WO3sensor by using (Pt+Pd+Rh)@Al2O3as a catalytic film material and (Pt+Rh)-WO3as a gas-sensitive film material. Using temperature dynamic modulation, the (Pt+Pd+Rh)@Al2O3/(Pt+Rh)-WO3sensor was realised to improve the selectivity for mustard. Due to the catalytic effect of the (Pt+Pd+Rh)@Al2O3catalytic film on mustard, mustard was able to be catalytically generated into mustard sulphoxide after passing through the (Pt+Pd+Rh)@Al2O3catalytic film. Under a certain temperature dynamic modulation, the mustard concentration on the surface of the (Pt+Rh)-WO3gas-sensitive film showed an increase and then a decrease. Since the resistance response of the (Pt+Rh)-WO3gas-sensitive film to mustard was much higher than that of mustard sulphoxide, the change in the resistance of the (Pt+Rh)-WO3gas-sensitive film was mainly determined by the change in the concentration of mustard, which led to the peak signal in the curve of its resistance response to mustard. The experimental results showed that the (Pt+Pd+Rh)@Al2O3/(Pt+Rh)-WO3sensor had peak signals in the resistance response to mustard only, and not in the resistance response to 12 interfering gases, such as carbon monoxide.