A Study of an n-TiO2 Coated QCM Sensor?s Response and Reversibility under CO2 Exposure

Carbon dioxide, or CO2 gas, is an important atmospheric gas in the environment. An increase in CO2 concentration affects environmental damage. On the other side, CO2 concentration increases from year to year. In line with this, there is a need to develop a measurement system of CO2 concentration with good performance. Thus, this study aims to develop a quartz crystal microbalance (QCM)-based CO2 sensor using titanium dioxide nanoparticles and to identify the response and reversibility levels. For this purpose, this study used five sensors with different thicknesses: Q1, Q2, Q3, Q4, and Q5, to identify the response and reversibility responses. The results show that the sensors had a frequency shift of 5.14 kHz (Q1), 5.19 kHz (Q2), 5.70 kHz (Q3), 5.78 kHz (Q4), and 6.05 kHz (Q5). The response times are 80.1 s (Q1), 82.8 s (Q2), 84.6 s (Q3), 85.5 s (Q4), and 247.5 s (Q5). The frequency shifts and the response times indicate that Q5 has the best response for CO2. All sensors have fast recovery times, 10.8 s to 21.6 s. It can be concluded that the developed sensors have good response times, recovery times, and reversibility levels for CO2 gas detection. This sensor can be used as an alternative to a CO2 gas concentration measurement system, providing a novel and rapid detection method and fast recovery time.