Highly sensitive NO2 gas sensor based on ozone treated graphene

In the present study, we report a simple and reproducible method to improve the sensing performance of a graphene gas sensor using ozone treatment and demonstrate it with nitrogen dioxide (NO2) gas. The ozone-treated graphene (OTG) sensor demonstrated remarkable enhancement of the sensing performances such as percentage response, detection limit and response time. The percentage response of the OTG sensor was twofold higher than that of a pristine graphene sensor when it was exposed to 200 ppm concentration of NO2 at room temperature. It is noteworthy that significant improvement was achieved in the response time by a factor of 8. Extremely low parts-per-billion (ppb) concentrations were clearly detectable, while the pristine graphene sensor could not detect NO2 molecules below 10 ppm concentration. The detection limit of the OTG sensor was estimated to be 1.3 ppb based on the signal to noise ratio, which is the cutting-edge resolution. The present ozone treatment may provide an effective way to improve the performance of the graphene-based sensor, given its simple process, practical usability and cost effectiveness.