Highly sensitive ethanol gas sensors based on Co-doped SnO2 nanobelts and pure SnO2 nanobelts

An ethanol gas sensor based on Co-doped SnO2 nanobelts was fabricated in this work. Co-doped SnO2 nanobelts were prepared by chemical vapor deposition method (CVD) as sensing materials, and gas sensors were prepared by powder screen printing technology. Concurrently, a gas sensor based on pure SnO2 nanobelts was prepared under the same conditions for comparison. Various techniques were used to characterize the morphology and structure of the Co-doped SnO2 nanobelts to confirm that cobalt ions were successfully bound to the SnO2 body and existed in the host lattice as 2+ and 3+ valence states. Furthermore, the synthesized Co-doped SnO2 nanobelts and pure SnO2 nanobelts were evaluated for gas sensor applications at different operating temperatures and ethanol gas concentrations. The optimized temperatures for the gas sensors based on Co-doped SnO2 nanobelts and pure SnO2 nanobelts were 300 °C and 340 °C, respectively. For even a very low concentration of 50 ppm, Co-doped SnO2 nanobelts and pure SnO2 nanobelts gas sensors exhibited gas responses of 8.1 and 6.5 at their respective optimized temperatures, respectively. Therefore, the gas sensor based on Co-doped SnO2 nanobelts exhibited better gas response than pure SnO2 nanobelts based gas sensors. In addition, the response time and recovery time of the Co-doped SnO2 nanobelts gas sensor were shortened by 16 s and 5 s, respectively, compared with the pure SnO2 nanobelts gas sensor.