Tin Acetylacetonate as a Precursor for Producing Gas-Sensing SnO2 Thin Films

To expand the range of precursors used in the sol-gel technology for applying nanostructured SnO2 thin films promising as components of semiconductor chemical gas sensors, the efficiency of using tin acetylacetonate solutions with various precursor concentrations was demonstrated. It was determined that finely divided SnO2 with a crystallite size of 3-4 nm (cassiterite) can be obtained by hydrolysis by atmospheric moisture in the course of solvent evaporation at room temperature. Using tin acetylacetonate solutions with various precursor concentrations for applying SnO2 thin films by dip coating to the surface of rough ceramic Al2O3-based substrates with platinum interdigital electrodes and a microheater resulted in significant differences in microstructure, continuity, thickness, and porosity of the produced coatings. In a lower-concentration (0.13 mol/L) tin acetylacetonate solution, a multilayer dense continuous SnO2 coating was applied, whereas in a higher-concentration (0.25 mol/L) solution, the formed layer comprised aggregated nanoparticles 30-60 nm in size and had much more defects and higher porosity. The sensitivity of the obtained thin-film nanostructures to the most practically important gaseous analytes: CO, H-2, CH4, CO2, and NO2. The produced two-dimensional nanomaterials were shown to be promising for detecting carbon monoxide at 200-300A degrees C in dry air.