Ultra-Sensitive Non-Enzymatic Ethanol Sensor Based on Reduced Graphene Oxide-Zinc Oxide Composite Modified Electrode

Abstract

In this paper, we report a reduced Graphene Oxide (rGO)-Zinc Oxide (ZnO) composite-based non-enzymatic ethanol sensor with an ultra-high sensitivity of 508.91 $\mu $ AmM−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 ( $R^{2}=0.957$ ). 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.