Transition metals (Fe, Co, and Ni) encapsulated in nitrogen-doped carbon nanotubes as bi-functional catalysts for oxygen electrode reactions

Transition metal nanoparticles (Fe, Co, and Ni) encapsulated in N-doped carbon nanotube hybrids were prepared, and the catalytic activities of three catalysts are compared and discussed. The optimized Co/N-CNT catalyst exhibits superb bifunctional catalytic activity with a ΔEvalue of 0.78 V.