Actinomorphic ZnO/SnO2 core–shell nanorods: Two-step synthesis and enhanced ethanol sensing propertied

• Actinomorphic ZnO/SnO2 core–shell nanorods (NRs) were synthesized via a facile two-step synthesis method.
• Compared with pure ZnO NRs, the ZnO/SnO2 core–shell NRs show an obvious improvement in gas sensing performance.
• The substantial improvement of the response can be explained by the space-charge model.

Actinomorphic ZnO/SnO2 core–shell nanorods (NRs) were synthesized via a facile two-step synthesis method, in which actinomorphic ZnO NRs (core) with the diameter about 450–1500 nm and the length about 2–7 μm were prepared in advance through a chemical solution method, and then a continuous SnO2 layer (shell) with the thickness about 20–25 nm was easily coated on the ZnO NRs via an ionic-layer adsorption and reaction method. Compared with pure ZnO NRs, the ZnO/SnO2 core–shell NRs showed an obvious improvement in gas sensing performance. The response of the sensor based on as-prepared ZnO/SnO2 NRs to 2000 ppm ethanol vapor was as high as 230 at 300 °C, which was 7 times higher than that of ZnO based sensor. This substantial improvement of the response can be explained by the space-charge model.