Design of SnO2/ZnO hierarchical nanostructures for enhanced ethanol gas-sensing performance

Designing nanostructured materials to enhance gas-sensing performance is of important key for the next-generation sensor platforms. In this paper, a design of hierarchical SnO2/ZnO nanostructures for scalable fabrication of high-performance ethanol sensors is developed based on a combination of two simple synthesis pathways. High-quality single crystalline SnO2 nanowire (NW) backbones were first synthesized using the thermal evaporation method, whereas ZnO nanorod (NR) branches were subsequently grown perpendicularly to the axis of SnO2 NWs via the hydrothermal approach. The successful synthesis of SnO2/ZnO hierarchical nanostructures is confirmed by the results of scanning electron microscope, X-ray diffraction and photoluminescence spectrum. The ethanol-sensing properties of the SnO2/ZnO hierarchical nanostructures sensors were systematically investigated and compared to those of the bare SnO2 NWs sensor. The effect of growth manipulation of the SnO2/ZnO hierarchical nanostructures on the ethanol sensing characteristics was also studied. The results revealed that the design of the hierarchical nanostructures enhanced the ethanol gas response and selectivity for interfering gases such as NH3, CO, H2, CO2, and LPG. These enhancements are attributed to the enhancement of homogenous and heterogeneous NW–NW contacts. In addition, the results of this study may serve as a basis for designing various novel hierarchical nanostructures for other applications, including photocatalysis, battery electrode, solar cell, and nanosensors.