Carbon/Graphite Sheets/PTFE-Coated Porous Titanium as the Bipolar Plate by Hydrothermal Treatment

Abstract

A multilayered carbon–-Polytetrafluoroethylene/graphite sheet (C-PTFE/GS) coating is synthesized on a Ti plate by hydrothermal and immersion method. The innermost layer is composed of amorphous carbon and the outermost layer is made of a compound with PTFE, graphite sheets and nanotube. Interfacial contact resistance (ICR) decreases to 8.9 mΩ·cm−2 at the applied force of 1.4 MPa between carbon paper and the substrate with coating. The corrosive current density is only 0.49 μA/cm2 at the cathode, while the potential of 0.6 V is applied. The charge transfer resistance of the multilayer carbon coating is higher than that of a bare sample through the results of electrochemical impedance spectroscopy. Moreover, there are no obvious changes in the coating before and after potentiostatic polarization testing by X-ray photoelectron spectroscopy (XPS) analysis, which demonstrates the stability of multilayered C-PTFE/GS coating on Ti. In addition, the surface morphology of C-PTFE/GS coating is preserved without defect after potentiostatic polarization in a simulated environment of proton exchange membrane fuel cells (PEMFCs). Therefore, the C-PTFE/GS coating is potentially applied as bipolar plates in PEMFCs.