Robust Co-Embedded Nitrogen Doped Carbon Catalyst for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cell

This work reports non-noble, cobalt embedded nitrogen doped carbon (CoNC) catalysts for oxygen reduction reaction (ORR) in Nafion-based acidic proton exchange membrane fuel cells (PEMFCs). CoNC catalysts are synthesized through direct pyrolysis of two different zeolitic imidazolate framework (ZIF) precursors, Zn-ZIF and Co-ZIF. Profiting from two different precursor approach, appropriate assimilation of metal, nitrogen and carbon components is achieved which boosts oxygen reduction. Electrochemical results exemplified CoNC 3-1 catalyst derived from Zn-ZIF:Co-ZIF precursor in the weight ratio of 3 : 1 as the better ORR catalyst. CoNC 3-1 catalyst exhibited the highest electrochemical surface area (ECSA) (570 cm(2)), highest limiting current density (-5.14 mA cm(-2)) and followed near 4e(-) reduction of oxygen revealing superior ORR activity. The catalyst also demonstrated remarkable durability with loss of only 6 % of ECSA after 30,000 cycles of accelerated durability test. The enhanced ORR activity and durability is attributed to optimal balance of Co-N-x active sites along with appropriate N contents and graphitic carbon framework.