Nanocrystalline SnO₂ Functionalized with Ag(I) Organometallic Complexes as Materials for Low Temperature H₂S...

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.