• Ce micro-alloying significantly enhances the corrosion resistance of as-cast CoCrNi MEAs in 3.5wt.% NaCl solution, with optimal performance at 0.02at.% Ce.
• The addition of Ce reduces the passivation current density to a minimum of 26.383 μA·cm-2 and increases the breakdown potential to 0.471 VSCE, indicating superior protective film stability.
• The improvement is attributed to Ce modifying inclusions and forming a non-conductive precipitated phase, which enhances the passivation film's protective properties.
• This cost-effective micro-alloying strategy offers a promising route for improving the durability of CoCrNi MEAs in corrosive environments, with potential applications in aerospace, automotive, and marine industries.