Metal organic frameworks-derived sensing material of TiO2 thin film sensors for detection of NO2 gas

The poor conductivity of oxides such as TiO2 is the big challenge that severely restricts their applications in the gas sesnor field. The rational design of their electronic structure and nano/micro structure is an effective approach to solve this problem. The spin coating approach was used to create a combined strategy of MOF-derived TiO2 thin films in this work. Various characterization methods, such as XRD, Raman, TEM, and XPS analyses, were used to examine the produced sensor films. XRD and Tem results suggest that MOF could significantly improve the structural and morphological properties of TiO2. SEM and TEM clearly shows that TiO2 have nanoparticles and nanosheets morphologies and the spherical shaped individual nanoparticles sizes in the range of 25–35 nm was found in the TiO2 sample. Chemiresistive gas sensors made from this MOF-TiO2 had much better NO2-sensing capability than pristine TiO2, as well as higher sensitivity (response of 84.6% under 1000 ppm) and faster response and recovery times (45 s/57 s). The unique porous structure with high specific surface area and plentiful accessible active sites with surface-adsorbed oxygen is attributed to the MOF-derived TiO2 improved sensing capability.