SnO2 @ZnS core-shell hollow spheres with enhanced room-temperature gas-sensing performance

To detect flammable gases and lower energy consumption, room-temperature gas sensors with high sensitivity, selectivity and stability have attracted increasing attention. In this work, SnO2 @ZnS core-shell hollow spheres are prepared via a two-step hydrothermal method. The effects of morphology and composition on gas sensing performance were systematically investigated by adjusting the molar ratio of SnO2 to ZnS. Compared with pure SnO2 hollow spheres, the core-shell composites exhibit excellent enhanced sensing properties to n-butanol at room temperature. The SnO2 @ZnS (1:0.5) core-shell hollow spheres show the highest sensing response (12.6) to 100 ppm n-butanol at 25ºC, which was ∼4 times higher than that of the pristine SnO2 hollow spheres. The room-temperature sensing mechanism to n-butanol is proposed. The enhanced sensing mechanism of the core-shell structure is attributed to i) the uniform hollow structure, ii) the electron transfer to surface induced by SnO2 metallization and the formation of n-n heterojunction, and iii) high charge carrier density and fast charge transfer rate. This study provides a novel core-shell hollow structure for room-temperature detection of n-butanol.