Core-shell ZnO/SnO2 nanorods (NRs) were successfully synthesized via a
facile two-step synthesis route. ZnO NRs (core) with the diameter about 300–800 nm
and the length about 2-2.5 µm were first synthesized via a hydrothermal route, and
then a continuous SnO2 layer (shell) with the thickness about 20-25 nm was easily
coated on the ZnO NRs via a solvothermal route. Compared with pure ZnO NRs and
SnO2 nanoparticles (NPs), the ZnO/SnO2 core-shell NRs show an obvious enhancement
in gas sensing performance. The response of the sensor based on as-prepared ZnO/SnO2 core-shell NRs to 100 ppm
ethanol is as high as 29.5 at 340 °C, and the response and recovery time are found to be about 18 s and 11 s, respectively.
The gas sensing mechanism of the ZnO/SnO2 core-shell NRs was discussed in relation to ZnO/SnO2 heterojunctions.