Effect of a porous Pt/alumina cover layer for V₂O₅/WO₃/TiO₂ resistive SO₂ sensing materials

Abstract

Planar resistive type SO₂ sensors based on V₂O₅/WO₃/TiO₂ (VWT) have been reported to respond well to SO₂ but with large cross-effects of NO and NH₃. In this study, we added a porous Pt/alumina cover layer on a VWT film in order to decrease the cross sensitivities. The sensor response to SO₂ is hardly affected by the Pt/alumina layer in the case of VWT sensor with 3.0 wt % V₂O₅ with Au electrodes, while the Pt/alumina layer affects the response of other VWT sensors. The VWT sensor (3.0 wt % V₂O₅) with Au electrodes with the porous Pt/alumina cover layer shows much smaller responses to CO, H₂, H₂O, NH₃, and NO compared with the sensor without Pt/alumina cover layer. The porous Pt/alumina cover layer has a potential to improve the selectivity of the VWT sensor.