Dissolved Oxygen Sensor Based on Reduced Graphene Oxide

The monitoring of dissolved oxygen (DO) in water is of great interest in order to provide information concerning the presence of pollutants or more generally about the health state of aquatic ecosystems. The majority of existing dissolved oxygen analyzers use electrochemical sensors which are accurate, reliable, stable, and require low or zero maintenance. However, these commercial sensors are not very compact and relatively expensive, since the fabrication process is complicated and noble metals are normally used as electrode materials. Herein, we present an electrochemical sensor for the determination of dissolved oxygen, by using reduced graphene oxide (RGO) as the oxygen sensitive probe. We prepared RGO by a chemical reduction method from graphene oxide (GO). A simple sensor was fabricated by printing RGO dispersed in Nafion, on the working electrode surface of a flexible commercial device. The surface and morphological properties of the sensing layer were investigated by XPS and TEM analysis. The electrochemical characteristics of the RGO-modified electrode were investigated by cyclic voltammetry (CV). Amperometric measurements were also performed in order to evaluate the sensor performance. Preliminary tests show good sensitivity and reproducibility. Tests of dissolved oxygen monitoring on environmental samples show the possibility of use in real applications.