Ag/Reduced Graphene Oxide/Carbon Fiber Composites as Electrodes for Highly Stable and Responsive Marine Electric Field Sensors

The increasing demand for maintenance-free, cost-effective, and high-stability flexible electrodes is highly anticipated for the research of marine electric-field sensors, and various carbon fibers (CFs) are considered the most suitable carbon-based electrode for the purpose. Nevertheless, the conventional fabrication of acidified or nitrogenized CF electrodes did not attract great attention for commercial application, which has limitations in the case of simultaneous cost-effectiveness and long-term stability. In this study, with homemade reduced graphene oxide (rGO) load, the prepared double carbon substrate Ag-rGO-CF composite electrodes have a honeycomb rGO conductive skeleton and the dispersed Ag nanoparticles via a facile hermetic oxidation process and hydrothermal method. The prepared Ag-rGO-CF composite electrode demonstrated an outstanding electrode performance, including low resistance, high electrochemical reaction rate, and stable potential with long-term stability and low cost. The electric double-layer (EDL) structure theory from the Gouy–Chapman–Stern model and double carbon substrate mechanism between CFs and rGO with the help of Ag were clarified, whose principle is to strengthen the adsorption force and electrostatic attraction of the electrode and to offset the residual charge while reducing the thickness of the electric double layer to achieve the purpose of potential balance. The Ag-rGO-CF composite electrode has presented long-term stability and high sensitivity, especially a wide application bandwidth. The Ag-rGO-CF composite electrode made in this study is a competitive candidate material as a flexible marine electrode field sensor.