Highly sensitive and selective room-temperature NO2 gas sensor based on bilayer transferred chemical vapor deposited graphene

This work presents a highly sensitive room-temperature gas sensor based on bilayer graphene fabricated by an interfacial transfer of chemical vapor deposited graphene onto nickel interdigitated electrodes. Scanning electron microscopic and Raman spectroscopic characterizations confirm the presence of graphene on interdigitated nickel electrodes with varying numbers of graphene layers. The NO2 detection performances of bilayer graphene gas sensor have been investigated in comparison with those of monolayer and multilayer graphene gas sensors at room temperature. From results, the bilayer graphene gas sensor exhibits higher response, sensitivity and selectivity to NO2 than monolayer and multilayer graphene. The sensitivity of bilayer graphene gas sensor is 1.409 ppm−1 towards NO2 over a concentration range of 1-25 ppm, which is more than twice higher than that of monolayer graphene. The NO2-sensing mechanism of graphene sensing film has been explained based on the direct charge transfer process due to the adsorption of NO2 molecules.