H2S gas sensing properties of Fe2O3 nanoparticle-decorated NiO nanoplate sensors

Fe2O3 nanoparticles and Fe2O3 nanoparticle-decorated NiO nanoplates were synthesized via a facile solvothermal route using FeCl3, nickel acetate, and NaOH as starting materials. The structure and morphology of the synthesized nanoparticles were examined using X-ray diffraction and scanning electron microscopy, respectively. The gas sensing properties of the Fe2O3 nanoparticles and Fe2O3 nanoparticle-decorated NiO nanoplate sensors toward H2S gas were examined at different concentrations of H2S (5-200 ppm) gas at various temperatures (200-350 °C). The Fe2O3 nanoparticle-decorated NiO nanoplate sensor exhibited a stronger response to H2S than the Fe2O3 nanoparticle sensor. The response of the Fe2O3 nanoparticle-decorated NiO nanoplate sensor was 26.55 for 200 ppm H2S at 300 °C, whereas the maximum response of the Fe2O3 nanoparticle sensor was 7.46 under the same condition. The Fe2O3 nanoparticle-decorated NiO nanoplate sensor also exhibited shorter response and recovery times than those of the Fe2O3 nanoparticle sensor. The improved sensing performance of the Fe2O3 nanoparticle-decorated NiO nanoplate sensor was attributed to the enhanced modulation of the conduction channel width and potential barrier height at the NiO-Fe2O3 interface, catalytic activity of NiO in the oxidation of H2S, larger surface-to-volume ratio of the decorated sensor, and stronger adsorption of oxygen molecules by p-type NiO.