Amino-tethering synthesis strategy toward highly accessible sub-3-nm L10-PtM catalysts for high-power fuel cells

Because of the poor accessibility of embedded active sites, platinum (Pt)-based electrocatalysts suffer from insufficient Pt utilization and mass transport in membrane electrode assemblies (MEAs), limiting their performance in polymer electrolyte membrane fuel cells. Here, we report a simple and universal approach to depositing sub-3-nm L10-PtM nanoparticles over external surfaces of carbon supports through pore-tailored amino (NH2)-modification, which enables not only excellent activity for the oxygen reduction reaction, but also enhanced Pt utilization and mass transport in MEAs. Using a low loading of 0.10 mgPt·cm−2, the MEA of PtCo/KB-NH2 delivered an excellent mass activity of 0.691 A·mgPt−1, a record-high power density of 0.96 W·cm−2 at 0.67 V, and only a 30-mV drop at 0.80 A·cm−2 after 30,000 voltage cycles, which meets nearly all targets set by the Department of Energy. This work provides an efficient strategy for designing advanced Pt-based electrocatalysts and realizing high-power fuel cells.