Evaluation of the VOCs sensing capacity of nanostructured TiO₂ film plasma coated QCM transducer

This study investigates the use of titanium dioxide (TiO2) thin films, deposited by low-frequency plasma-enhanced chemical vapor deposition (PECVD) on quartz crystal microbalance (QCM) transducer for the detection of volatile organic compounds (VOCs) such as methanol, ethanol, acetone, and toluene. Using titanium tetraisopropoxide (TTIP) as an organometallic precursor, the films were synthesized at plasma discharge power of 20 W and substrate temperature of about 150°C in order to improve their physicochemical and morphological features. Analyses through Fourier Transform Infrared Spectroscopy (FTIR) confirmed the formation of Ti-O bonds and the presence of functional groups like hydroxyl and carbonyl, which are important for VOC adsorption. Atomic Force Microscopy (AFM) revealed the growth of rough surface QCM coating leading to increased specific sensor surface area (surface to volume ratio). The elaborated sensitive layer showed high sensitivity and affinity in detecting VOC molecules with ethanol detection being particularly effective due to hydrogen bonding with surface hydroxyl groups. These results highlight the potential of PECVD in developing TiO2 based-sensors with increased porosity and surface area, contributing significantly to advances in environmental monitoring and industrial safety.