Enhanced H2S sensing performance of TiO2-decorated α-Fe2O3 nanorod sensors

Pristine and TiO2 nanoparticle-decorated Fe2O3 nanorods were synthesized via thermal oxidation of Fe thin foils, followed by the solvothermal treatment with titanium tetra isopropoxide (TTIP) and NaOH for TiO2 nanoparticle-decoration. Subsequently, gas sensors were fabricated by connecting the nanorods with metal conductors. The structure and morphology of the pristine and TiO2 nanoparticle-decorated Fe2O3 nanorods were examined via X-ray diffraction and scanning electron microscopy, respectively. The gas sensing properties of the pristine and TiO2 nanoparticle-decorated Fe2O3 nanorod sensors with regard to H2S gas were examined. The TiO2 nanoparticle-decorated Fe2O3 nanorod sensor showed a stronger response to H2S than the pristine Fe2O3 nanorod sensor. The responses of the pristine and TiO2 nanoparticle-decorated Fe2O3 nanorod sensors were 2.6 and 7.4, respectively, when tested with 200 ppm of H2S at 300 °C. The TiO2 nanoparticle-decorated Fe2O3 nanorod sensor also showed a faster response and recovery than the sensor made from pristine Fe2O3 nanorods. Both sensors showed selectivity for H2S over NO2, SO2, NH3, and CO. The enhanced sensing performance of the TiO2 nanoparticle-decorated Fe2O3 nanorod sensor compared to that of the pristine Fe2O3 nanorod sensor might be due to enhanced modulation of the conduction channel width, the decorated nanorods' increased surface-to-volume ratios and the creation of preferential adsorption sites via TiO2 nanoparticle decoration. The dominant sensing mechanism in the TiO2 nanoparticle-decorated Fe2O3 nanorod sensor is discussed in detail.