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

Abstract Pristine and TiO 2 nanoparticle-decorated Fe 2 O 3 nanorods were synthesized via thermal oxidation of Fe thin foils, followed by the solvothermal treatment with titanium tetra isopropoxide (TTIP) and NaOH for TiO 2 nanoparticle-decoration. Subsequently, gas sensors were fabricated by connecting the nanorods with metal conductors. The structure and morphology of the pristine and TiO 2 nanoparticle-decorated Fe 2 O 3 nanorods were examined via X-ray diffraction and scanning electron microscopy, respectively. The gas sensing properties of the pristine and TiO 2 nanoparticle-decorated Fe 2 O 3 nanorod sensors with regard to H 2 S gas were examined. The TiO 2 nanoparticle-decorated Fe 2 O 3 nanorod sensor showed a stronger response to H 2 S than the pristine Fe 2 O 3 nanorod sensor. The responses of the pristine and TiO 2 nanoparticle-decorated Fe 2 O 3 nanorod sensors were 2.6 and 7.4, respectively, when tested with 200 ppm of H 2 S at 300 °C. The TiO 2 nanoparticle-decorated Fe 2 O 3 nanorod sensor also showed a faster response and recovery than the sensor made from pristine Fe 2 O 3 nanorods. Both sensors showed selectivity for H 2 S over NO 2 , SO 2 , NH 3 , and CO. The enhanced sensing performance of the TiO 2 nanoparticle-decorated Fe 2 O 3 nanorod sensor compared to that of the pristine Fe 2 O 3 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 TiO 2 nanoparticle decoration. The dominant sensing mechanism in the TiO 2 nanoparticle-decorated Fe 2 O 3 nanorod sensor is discussed in detail.