Constructing Highly Durable Fuel Cell Catalysts Through Integrating Graphitic Shell-Protected Composite Carbon...

Metal dissolution, nanoparticle agglomeration, and carbon support corrosion cause significant performance degradation of current PtCo catalysts under acidic and oxidative oxygen reduction reaction. Here, an integrated strategy is presented to design high-performance Pt₃Co intermetallic catalysts by regulating gaseous Co deposition-driven diffusion into Pt nanoparticles supported on a composite carbon. The composite carbon is derived from ZIF-8/polyaniline, consisting of a high-surface-area (HSC) core and a protective graphitic shell (GS), which is employed to design 40 wt.% Pt/HSC@GS catalyst. The corresponding membrane electrode assemblies (MEAs) can maintain 1.09 A cm^-2 at 0.7 V (20. 7% loss) after 10 000 cycles (1.0-1.5 V for carbon stability) and 1.15 A cm^-2 (16.1% loss) after 150 000 cycles (0.60-0.95 V for catalyst stability). A ordered Pt₃Co intermetallic is synthesized via a gaseous Co-deposition process, which yields a homogeneous Co-rich layer onto the Pt nanoparticles on the composite support, thereby facilitating Co diffusion into Pt crystal during subsequent ordering annealing to form the ordered intermetallic structure. This gaseous deposition leads to a thin carbon layer on PtCo nanoparticles, inhibiting particle growth during the annealing and mitigating Co dissolution under dynamic electrochemical conditions. The PtCo catalyst achieves impressive MEA performance and long-term durability (1.45 A cm^-2 at 0.7 V after 120 000 cycles) under heavy-duty conditions.