VOC Gas Sensor Based on ZnO Synthesized by Sol–Gel Process and Improvement in Gas Sensitivity by Adding TiO₂

Abstract

Transparent ZnO gel was synthesized by sol-gel process. In order to getting fine powder of ZnO, at the beginning, ZnO gel was disposed with the pre-firing at 300°C. And then, ZnO powder was calcined at different temperature of 500 °C, 700 °C and 900 °C, the grain size of ZnO powder was different. This paper reports the sensitivity of ZnO gas sensor to three volatile organic compound (VOC) gases (acetone, ethanol and toluene). As we all know, these VOC gases are deleterious to global environment and our health. For different VOC gases, the optimum operating currents and the corresponding sensitivities were different. This paper also researched a nicely sensitive indirect- heating type thick film ZnO gas sensor by adding TiO2. TiO2 was mixed in weight percentage of 2%. The compound oxide sensor debased the optimum working currents of ethanol and toluene. And this sensor also showed rapid response-recovery time, which was propitious to practicability of ZnO gas sensor.