Improving the humidity sensing below 30% RH of TiO2 with GO modification

Abstract The development of cost-effective, robust, and reliable humidity monitoring system is nowadays in high demand. To this context, humidity sensors based on rutile TiO 2 aggregates were prepared via thermal oxidation of pure Ti-discs at 1000 °C. The sensors based on only TiO 2 aggregates exhibited the ultra-high response of about six orders of magnitude (R A /R %RH ∼ 10 6 ) to 90% RH with a response time of 28 s and excellent stability. However, these sensors showed no response to RH below 30%, which limits their use in practical applications for such RH level monitoring. Although with a reduced response in high RH, the TiO 2 modified with GO showed potential to overcome this drawback. To understand their functionality, the TiO 2 aggregates and TiO 2 /GO were further characterized by XRD, SEM, TEM, Raman and FT-IR spectroscopy. The presented results are of high interest in terms of wide range humidity monitoring, low-cost and simple synthesis route, and high stability.