Engineering ionomer homogeneously distributed onto the fuel cell electrode with superbly retrieved activity towards oxygen reduction reaction

[Display omitted] •Pt/C electrode with unprecedented-thin ionomer layer is demonstrated via HH-ESD.•Hierarchical structure with uniform distribution of ionomer is successfully created.•This electrode exhibits 3x mass activity and 2x cell performance at 0.1 mgPt/cm2.•Durability towards carbon corrosion is notably enhanced due to hydrophobic nature. Polymer electrolyte fuel cell electrode, especially at lower Pt loadings, suffer from an inevitable performance reduction, primarily as a result of reduced catalytic activity and enlarged mass-transport resistance triggered by ionomer layer enveloping Pt. In course of the conventional slurry method, severe agglomeration leads to formation of larger ionomer particles attributed to electrostatic attraction between sulfonic acid groups and Pt, effectuating catalytic poisoning and creating substantially tortuous pathways for O2. Here, we propose an electrode architecture with infinitesimally thin ionomer deposited onto Pt using electrostatic spray deposition under hot and humid environments. The resultant electrode possesses a hierarchical structure with distinctively homogeneous distribution of ionomer, enabling tripled mass activity and doubled cell performance when compared to the state-of-the-art decal-transferred electrode, and concurrently, improved stability towards carbon degradation. Given the cost-effectiveness and excellent scalability, this work leads the way towards a sustainable trajectory in the long-term targets on global hydrogen mobility.