Fabrication of ZnO quantum dots@SnO2 hollow nanospheres hybrid hierarchical structures for effectively detecting formaldehyde

The ZnO quantum dots modified SnO2 hollow nanospheres (ZnO QDs@SnO2 HNSs) hybrid hierarchical structures were fabricated by modifying ZnO QDs on the surface of SnO2 HNSs using precipitation and hydrothermal method. The gas sensors based on ZnO QDs, SnO2 HNSs and ZnO QDs@SnO2 HNSs present superior sensing properties to formaldehyde compared with three other typical indoor volatile organic compounds (VOCs, including formaldehyde, toluene, benzene and ammonia). In particular, the ZnO QDs@SnO2 HNSs based sensor exhibits high response (36.5-50 ppm), good linearity (1-1000 ppm), rapid response/recovery time (9 s/10 s), ultra-low limit of detection (LOD, 5 ppb) and excellent long-term stability. The ZnO QDs@SnO2 HNSs hybrid hierarchical structures not only ensure the porosity but also create lots of heterojunctions, which is benefit for improving the gas sensing properties of a gas sensor.