In₂O₃/SnO₂ heterojunction microstructures: Facile room temperature solid-state synthesis and enhanced Cl₂ sensing performance

A facile room temperature solid-state reaction route was employed to synthesize the In₂O₃/SnO₂ heterojunction microstructures by grinding indium nitrate hydrate, tin dioxide and sodium hydroxide with proper molar ratios together without any surfactant and template. Their morphological feature is characterized as self-assembled by irregular-shaped nanospheres, and it was observed that a large quantity of nanocrystals with the size of 20-50 nm were present on In₂O ₃ sphere surfaces. The introduction of a small quantity of SnO ₂ in the reaction system was played an important role in the size- and shape-control. Furthermore, gas sensing properties of them were characterized in detail. The sensor based on In₂O₃/ SnO₂ heterojunction microstructures exhibited a much higher response to Cl₂ than the sensor based on pure In₂O₃ nanostructures, and the In/Sn = 12:1 (molar ratio) sample showed the highest response with quick response-recovery behavior as well as good selectivity and stability. The largest surface area of the In₂O₃/SnO ₂ heterojunction microstructures was also clarified by the analysis of nitrogen adsorption-desorption test, which contributes the great enhancement of the Cl₂ gas sensing properties.