UIO-66-NH₂-Derived Mesoporous Carbon Catalyst Co-Doped with Fe/N/S as Highly Efficient Cathode Catalyst for PEMFCs

Efficient, low-cost catalysts are desirable for the sluggish oxygen reduction reaction (ORR). Herein, UIO-66-NH₂-derived multi-element (Fe, S, N) co-doped porous carbon catalyst is reported, Fe/N/S-PC, with an octahedral morphology, a well-defined mesoporous structure, and highly dispersed doping elements, synthesized by a double-solvent diffusion-pyrolysis method (DSDPM). The morphology of the UIO-66-NH₂ precursor is perfectly inherited by the derived carbon material, resulting in a high surface area, a well-defined mesoporous structure, and atomic-level dispersion of the doping elements. Fe/N/S-PC demonstrates outstanding catalytic activity and durability for the ORR in both alkaline and acidic solutions. In 0.1 m KOH, its half-potential reaches 0.87 V (vs reversible hydrogen electrode (RHE)), 30 mV more positive than that of a 20 wt% Pt/C catalyst. In 0.1 m HClO₄, it reaches 0.785 V (vs RHE), only 65 mV less than that of Pt/C. The catalyst also exhibits excellent performance in acidic hydrogen/oxygen proton exchange membrane fuel cells. A membrane electrode assembly (MEA) with the catalyst as the cathode reaches 700 mA·cm^-2 at 0.6 V and a maximum power density of 553 mW·cm^-2, ranking it among the best MEAs with a nonprecious metal catalyst as the cathode.