Single-Atom and Hierarchical-Pore Aerogel Confinement Strategy for Low-Platinum Fuel Cells

Achieving high catalytic performance through the lowest possible content of platinum (Pt) is the key to cost reduction of proton-exchange-membrane fuel cells (PEMFCs). However, lowering the Pt loading in PEMFCs leads to the high mass-transport resistance of oxygen originating from the limited active sites, and causes less stability of the catalysts due to Pt size growth after long-time operation. Herein, Pt-metal/metal-N-C aerogel catalysts are designed that substantially reduce oxygen-related mass transport resistance and have long-term durability. The tailoring of the Fe-N-C aerogel support with hierarchical and interconnecting pores enable a low local oxygen transport resistance (0.18 s cm^-1 ) for PEMFCs with ultralow Pt loading (50 ± 5 µg_Pt cm^{- 2} ). Chemical confinement of Fe─N sites ensures high stability of the loaded-Pt both in the processes of synthesis up to 1000 °C and practical application in PEMFCs. The ultralow Pt PEMFC displays a low voltage loss of 8 mV at 0.80 A cm^{- 2} and unchanged electrochemical surface area after 60 000 cycles of accelerated durability testing. The allying of the hierarchical pores, the aerogel, and the single atoms can fully reflect their structural advantages and expand the understanding for the synthesis of advanced fuel cell PEMFCs catalysts.