Quartz Crystal Microbalance Coated with Vanadium Oxide Thin Film for CO2 Gas Sensor at Room Temperature

A gas-sensing device based on quartz crystal microbalance (QCM) covered with vanadium oxide thin film has been elaborated to detect CO2 gas at room temperature. Vanadium oxide thin films were deposited onto QCM substrates by vacuum thermal evaporation technique. The vanadium oxide-coated QCM was heated at 200 degrees C for different times. The influence of the annealing time on structural and morphological properties of the deposited films was investigated by scanning electron microscopy, atomic force microscopy, and X-ray diffraction. The elaborated QCM/vanadium oxide structures were tested for CO2 gas sensing. The results show that the sensor sensitivity increases with the annealing time due to the increase in the roughness of the surface. Moreover, the structure heated at 200 degrees C for 3 h exhibited a high resonance frequency shift (Delta f) under a CO2 pressure of 40 mbar, fast response time (57 s), short recovery time (43 s), good stability, linearity, reproducibility, and reversibility.