Graphene-Based Gas Sensors with High Sensitivity and Minimal Sensor-to-Sensor Variation

Graphene as an atom-thick carbon material is promising for the detection of gaseous molecules owing to extremely high surface-to-volume ratio. However, majority of graphene-based gas sensors, prepared by chemical vapor deposition (CVD), have suffered from non-uniformity in their responses. Such a high sensor-to-sensor variation in responses has not been systematically studied, limiting application of graphene gas sensors. Here we report processes that lead to a highly sensitive and uniform graphene gas sensor. We examined four types of graphene sensors by varying two conditions: 1) whether or not there is a carbon precursor while cooling down the reactor after graphene synthesis, and 2) whether poly(methyl methacrylate) (PMMA), a polymer for transferring the graphene onto another substrate, is removed by annealing at high temperature or by rinsing with acetone. Using 5 ppm dimethyl methylphosphonate (DMMP), a nerve agent simulant, as a model analyte, we found that uniform responses are obtained by cooling...