Fig. 4: Fuel cell performance and durability tests.

Polarization and power density curves before and after 30,000 cycles for a PtMg/C-31, b Pt/C, and c PtMg/C-11 in H2-O2 condition. Polarization and power density curves before and after 30,000 cycles for d PtMg/C-31, e Pt/C, and f PtMg/C-11 in H2-air condition. Histograms of g mass activities, h peak power densities of PtMg/C-31, Pt/C, and PtMg/C-11 before and after 30,000 ADT cycles in H2-O2 gas flow, and i cell voltages recorded at 0.8 A cm−2 in H2-air for the three catalysts before and after the 30,000 ADT (DOE Target <30 mV drop after ADT). Note: Detailed measurement conditions are indicated in the methods section. Error bars indicate the standard deviation for three independent measurements.