Figure 17.

(a) Schematics of LP@PF catalysts, showing coexistence of Pt-Co NPs, Co@graphene, and Co-Nx-Cy PGM-free active sites. (b) HAADF-STEM image of Pt-Co NPs in LP@PF-1. (c) PGM-free support containing atomically dispersed Co (circled in red) and trace Pt (circled in blue). (d) LSVs of different catalysts recorded at a rate of 10 mV s⁻¹ and 1600 rotations per minute in O₂-saturated 0.1 M HClO₄; j, current density. (e) H₂-O₂ fuel cell i-V polarization (solid symbols and lines) and power density (hollow symbols and dashed lines) plots recorded under 1 bar of O₂ pressure with cathode Pt loading of 0.033 mg_Pt cm⁻² for LP@PF-1 (black stars), 0.035 mg Pt cm⁻² for LP@PF-2 (red diamonds), 0.043 mg_Pt cm⁻² for Pt₃Co/ZC (blue spheres), and 0.35 mg_Pt cm⁻² for commercial MEA (magenta squares); PF-2, green triangles. (f) Comparison of MAs at 0.9 V versus RHE. (g) Fuel cell (FC) MAs at 0.9 V iR-free before (solid) and after (hatched) 30,000 voltage cycles, showing that LP@PF catalysts meet or exceed DOE’s 2025 MA targets for before (green dashed line, 0.44 A mgPt⁻¹) and after (red dashed line, 0.264 A mgPt⁻¹ or 40% of the initial value) AST. [255]. Reprinted with permission from AAAS.