ZnO/graphene heterostructure for electrical interaction and application for CO2 gas sensing

Recently, the concentration of CO2, one of the major air pollutants for greenhouse effect, is increasing due to the massive use of fossil fuels. Thus, research about gas sensors for monitoring CO2 gas has performed, and conventional methods have the challenge of requiring complex structures. Thus, research about gas sensors using nanomaterials has been conducted, and graphene-based gas sensors have been actively researched for its extraordinary conductivity. However, there are challenges that the gas absorption site is limited in chemically unstable sites. In this study, ZnO/graphene heterostructure to improve the gas absorption area with high conductivity through ZnO on graphene was presented. Each layer acted as a gas adsorption and a carrier conducting layer respectively, and the sensitivity by the thickness of ZnO and the effect of the annealing temperature were evaluated. This work exhibited a sensitivity of 78% at room temperature, and repeatability and selectivity were also studied.