Synthesis of HMDSO/TiO2 composite on quartz crystal microbalance for enhanced volatile organic compounds gas sensing properties

In this study, HMDSO/TiO2 nanocomposite was synthesized on a quartz crystal microbalance (QCM) transducer by atmospheric pressure plasma jet (APPJ) for the detection of volatile organic compounds (VOCs). Fourier-transform infrared spectroscopy (FTIR) analysis revealed the presence of Ti-O-Ti bond around 580 cm-1 , indicating the growth of TiO2 film on the HMDSO support layer. X-ray diffraction (XRD) analysis confirmed the presence of rutile and anatase phases of TiO2, demonstrating that the APPJ method can produce crystalline films in a single process without post-thermal annealing. Atomic force microscopy (AFM) imaging showed the growth of rougher surface QCM coating, leading to an increased specific surface area and more absorption sites. Water contact angle (WCA) measurements showed that the hydrophilic QCM surface was transformed into super-hydrophobic one after coating with the HMDSO/TiO2 hybrid film. Compared to single layer VOCs sensors, the HMDSO/TiO2 heterostructure revealed good sensitivity, low response and recovery times across the explored VOC concentration range.