Site –selective, Low-loading, Au Nanoparticle-Polyaniline Hybrid Coatings with Enhanced Corrosion Resistance and Conductivity for Fuel Cells

Ultralow loading of Au nanoparticles (0.038 mg cm–2) and a polyaniline hybrid coating (AuNP-PANI) were deposited on stainless steel (SS316L) coupons. The unique two-step approach utilizing electrochemical deposition via cyclic voltammetry enabled growth of AuNPs in the fibrous PANI micropores thereby achieving enhanced surface coverage of SS316L and minimizing substrate corrosion via blocking of pores. The hybrid coatings revealed significantly low interfacial contact resistance values of 16.6 mΩ cm2 (achieving the US DOE 2017 targets). Potentiodynamic tests revealed the excellent corrosion resistance of AuNP-PANI hybrid coatings with a corrosion potential of 0.61 VSHE, which is positively shifted by 790 and 390 mV as compared to bare SS316L and PANI-SS316L, respectively. The corresponding potentiostatic corrosion current density of AuNP-PANI was reduced to 0.63 μA/cm2 from 2.28 and 0.65 μA/cm2 for bare SS316L and PANI-SS316L samples, respectively, thereby providing excellent stability in the cathodic pol...