Dual-atomic-sites anchored on nanosized hollow polyhedron to boost oxygen reduction reaction in acidic electrolyte

Fe and Co dual atomic sites anchored on a hollow carbon nanocage (Fe/Co–N–C) have shown notable advantages in improving the activity and stability toward the oxygen reduction reaction (ORR) in the acidic media. However, it is yet challenging to design such nanostructured Fe/Co–N–C electrocatalysts in a simple manner. In this research, hollow polyhedral carbon nanocages modified by Fe, Co-dual metal atoms are designed from ZIF-8 which involves cage-inclusion of mixed metal salts and conversion to mixed metal hydroxides before high-temperature pyrolysis. The optimized Fe/Co–N–C demonstrated one of the best acidic ORR performances, exhibiting a half-wave potential (E1/2) of 0.81 V (vs. RHE) in 0.5 M H2SO4, and a slight decay of 13 mV in E1/2 after 10,000 cycles. Compared to Fe–N–C counterpart, the improved ORR performance of Fe/Co–N–C is attributed to the synergism between Fe-Nx and Co-Nx active sites, which are attested by various characterizations and control experiments.