Ultra-sensitive non-enzymatic ethanol sensor based on Reduced Graphene Oxide-Zinc Oxide composite modified electrode

In this work, we report a reduced Graphene Oxide (rGO)-Zinc Oxide (ZnO) composite based non-enzymatic ethanol sensor with an ultra-high sensitivity of 508.91 μAmM-1cm-2 which is, to the best of our knowledge, ~8 folds higher than previously reported electrochemical ethanol sensors. The rGO-ZnO composite was synthesized by a wet chemical method wherein the reduction of GO and intimate interfacial contact between ZnO NPs and rGO were achieved simultaneously. The sensing of ethanol was explicated by means of current-potential (I-V) technique. The sensor exhibited reproducible response with insignificant variations in current tested across multiple electrodes and responded linearly to ethanol in the range of 0.5-5 mM (R²=0.957). The sensor also showed lower limit of detection. The significant improvement in sensitivity is attributed to the improved surface activity and faster charge separation owing to formation of the nano-Schottky barrier at rGO-ZnO interface. This approach is beneficial as it eliminates the use of conducting binder along with the functional material for ethanol sensing. This ultra-sensitive, binder free rGO-ZnO based sensor offers a simple, low cost approach for ethanol detection in food, pharmaceutical, bio fuel industries and environmental analyses