Nanocrystalline SnO 2 Functionalized with Ag(I) Organometallic Complexes as Materials for Low Temperature H 2 S Detection.

This paper presents a comparative analysis of H 2 S sensor properties of nanocrystalline SnO 2 modified with Ag nanoparticles (AgNPs) as reference sample or Ag organic complexes (AgL1 and AgL2). New hybrid materials based on SnO 2 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 H 2 S demonstrated high sensitivity, selectivity toward other reducing gases (H 2 (20 ppm), NH 3 (20 ppm) and CO (20 ppm)) and good reproducibility of the composites in H 2 S detection at low operating temperatures. The composite materials also showed a linear detection range in the concentration range of 0.12-2.00 ppm H 2 S even at room temperature. It was concluded that the predominant factors influencing the sensor properties and selectivity toward H 2 S in low temperature region are the structure of the modifier and the chemical state of silver. Thus, in the case of SnO 2 /AgNPs reference sample the chemical sensitization mechanism is more possible, while for SnO 2 /AgL1 and SnO 2 /AgL2 composites the electronic sensitization mechanism contributes more in gas sensor properties. The obtained results show that composites based on nanocrystalline SnO 2 and Ag(I) organic complexes can enhance the selective detection of H 2 S.