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 In2O3 sphere surfaces. The introduction of a small quantity of SnO2 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/SnO2 heterojunction microstructures was also clarified by the analysis of nitrogen adsorption–desorption test, which contributes the great enhancement of the Cl2 gas sensing properties.