Chemical modification of impregnated SnO2-In2O3 nanocomposites due to interaction of sensor components

Abstract

Composites of SnO2-In2O3 were synthesized by impregnation of In2O3 nanocrystals with SnCl4 solution. When the SnO2 concentration in the composite (Xw)SnO2 ≥20 wt%, crystalline SnO2 clusters of about 5 nm in size are formed on the surface of In2O3 nanocrystals. These clusters determine the conductivity and sensory properties of the composites and contain indium ions that are implanted in the cluster lattice during their growth on the surface of the In2O3 nanocrystals. The implantation of these ions into SnO2 clusters causes lattice deformation and increase in oxygen vacancies, which are centers of oxygen chemisorption. The maximum sensor response of the composites to H2 as well as the maximum oxygen chemisorption and maximum lattice deformation of SnO2 clusters are all achieved at (Xw)SnO2 = 40 wt%. In a second set of composites obtained by direct mixing of the powder components, unlike impregnated composites, the structure of the nanoparticles does not change during the synthesis. In this case, the effect of the mixing components on the sensor response is due only to transfer of electrons between the nanoparticles of the different components.