Selective gas sensors based on tin dioxide and hybrid oxohydroxoorganotin materials

The ultimate objective of this research is to draw new prospects in the gas sensing field by finely tuning the chemical nature, the texture and the morphology of the active layer to develop new type selective gas sensors. As an efficient gas sensor, selectivity is a remarkable parameter. Our approach is based on the design of molecular single precursors – alkynylorganotins which contain suitable functionalities required to obtain stable hybrid materials by the sol-gel method exhibiting selective gas detection towards harmful/toxic gases. Their gas sensing properties have been compared with those of tin dioxide (SnO2) nanoparticles synthesized by the hydrothermal route. A series of functional oxohydroxoorganotin-based materials (OXT5a, OXT5b, OXT5c, and OXT5d) as well as the SnO2 nanoparticles have been processed as films by the spin or drop coating method and characterized by XRD, FT-IR, RAMAN, AFM, SEM, TEM, N2 sorption and TGA-DTA measurements. Gas sensing studies show that one of the hybrid oxohydroxoorganotins exhibits an outstanding selective gas sensing response towards various gases, such as CO, H2, ethanol, acetone and NO2 whereas SnO2 nanoparticles present no obvious selective gas sensing ability under the same experimental condition. Thus, the best gas selectivity toward 100, 200, and 400 ppm of H2 (gas response: 12.65, 29.57 and 48.89) and 2, 4, and 8 ppm of NO2 (gas response: 18.84, 48.13 and 70.87 ppm) was achieved respectively at 100 °C and 200 °C for hybrid oxohydroxoorganotin-based film (OXT5a). On the other hand, SnO2 nanoparticles which prepared via a hydrothermal route under acidic and basic conditions, of a commercial tin dioxide particle suspension including potassium conterions, show how the impact of the counterion residuals on gas sensing behavior to an extent rather than size and surface area effects. Finally, both oxohydroxoorganotin-based and tin dioxide materials display superior gas sensing ability at low gas concentrations and even at low operating temperature which opens a fully new class of gas sensing materials as well as a new possibility to integrate organic functionality in gas sensing metal oxides