This paper presents a comparative analysis of H2S sensor properties of nanocrystalline SnO2 modified with Ag nanoparticles (AgNPs) as reference sample or Ag organic complexes (AgL1 and AgL2). New hybrid materials based on SnO2 and Ag(I) organometallic complexes were obtained. The microstructure, compositional characteristics and thermal stability of the composites were thoroughly studied by X-ray diffraction (XRD), X-ray fluorescent spectroscopy (XRF), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric analysis (TGA). Gas sensor properties to 2 ppm H2S demonstrated high sensitivity, selectivity toward other reducing gases (H2 (20 ppm), NH3 (20 ppm) and CO (20 ppm)) and good reproducibility of the composites in H2S detection at low operating temperatures. The composite materials also showed a linear detection range in the concentration range of 0.12-2.00 ppm H2S even at room temperature. It was concluded that the predominant factors influencing the sensor properties and selectivity toward H2S in low temperature region are the structure of the modifier and the chemical state of silver. Thus, in the case of SnO2/AgNPs reference sample the chemical sensitization mechanism is more possible, while for SnO2/AgL1 and SnO2/AgL2 composites the electronic sensitization mechanism contributes more in gas sensor properties. The obtained results show that composites based on nanocrystalline SnO2 and Ag(I) organic complexes can enhance the selective detection of H2S.
Keywords: Ag nanoparticles; Ag organometallic complexes; H2S sensor; low temperature detection; metal oxide gas sensor; nanocrystalline tin dioxide.