Graphene-Based Coatings on Stainless Steels for Proton Exchange Membrane Fuel Cell Bipolar Plates

摘要

Proton exchange membrane fuel cells (PEMFCs) are clean and efficient power resources. They only emit water vapor, thereby offering a viable approach to reduce greenhouse gas emissions. To make these power sources cost competitive, multiple approaches can be employed. A crucial component of these fuel cells, i.e. the graphite separator plates, are expensive and prone to fracture. While graphite has excellent corrosion resistance, its porous and brittle nature makes it difficult to shape into thin sheets. Moreover, graphite separator plates can account for 60% of the cost of the fuel cell. One approach to overcome these issues is the use of metallic substrates. However, potential candidates for this application must be both corrosion resistant and electrically conductive. In this study, the surface of stainless steels was modified to achieve enhanced corrosion resistance while retaining high electrical conductivity, ductility and low cost of the substrates. A graphene-based coating applied to different stainless steels was selected as the ideal surface modification. As-received and surface modified test coupons were subjected to electrochemical tests using a three-electrode flat cell in a simulated PEMFC environment, i.e. 0.01 M H2SO4 solution at 70°C. Scanning electron microscopy and X-ray diffraction were used to characterize the surface of the test coupons. Current results indicate that the surface modified coupons offer higher corrosion resistance than the as-received coupons.