Selective acetone gas sensors using porous WO3–Cr2O3 thin films prepared by sol–gel method

Abstract WO 3 –Cr 2 O 3 semiconducting thin films were prepared by sol–gel method. Acetone gas sensing properties were investigated. Monoclinic phase was obtained as determined by X-ray diffraction after WO 3 –Cr 2 O 3 films were sintered in oxygen atmosphere for 1 h at 500 °C (quenched after sintering). Porous structure was observed by using field emission scanning electron microscopy. Electrical properties were studied by conductivity measurement. The acetone vapor sensing properties of these thin films were found strongly influenced by the porous structure, the content of Cr 2 O 3 , the sintering temperature, and the cooling way. As-prepared WO 3 –Cr 2 O 3 thin films exhibit excellent acetone vapor sensing properties with the maximum sensitivity ~ 8.91 at 320 °C in air atmosphere with fast response and recovery time.