Enhanced corrosion resistance by polypyrrole and Ti3C2Tx-acrylic epoxy double-layer coating for 304SS bipolar plates of PEMFC

Stainless steel (SS) is a promising material for designing bipolar plates (BPs), but their further application is limited by serious corrosion problems in the acidic environment. Ti 3 C 2 T x is expected to be used for SS BPs coatings, while galvanic corrosion will occur after the damage of Ti 3 C 2 T x coating. Herein, a PPY/Ti 3 C 2 T x -AE double-layer coating (DC) is well-designed and prepared on 304SS BP, which is composed of an inner electropolymerized PPY layer and an outer Ti 3 C 2 T x -acrylic epoxy layer. When tested in 0.2 M HCl solution, the corrosion potential and corrosion current density of the DC are 38 mV and 0.00927 μA cm −2 respectively, which are superior to those of the PPY coating and the Ti 3 C 2 T x coating. Moreover, the DC presents the best long-term stability among the three coatings. The excellent corrosion resistance is attributed to the barrier and anodic protection effects as well as the solution of galvanic corrosion. The new coating system provides a new insight into the design of DC coatings of SS BPs.