Design of Co-NC as efficient electrocatalyst: The unique structure and active site for remarkable durability of proton exchange membrane fuel cells

Fe-N-C catalysts are promising alternatives to the platinum-group catalysts for use in oxygen reduction reactions of proton exchange membrane fuel cells. However, Fe-N-C catalysts suffer from poor durability, compared to non-precious metal catalysts, because of their accelerated demetallation by the Fenton reaction. In this study, we report the synthesis of a melamine-encapsulated Co-ZnO-C composite as a precursor and template for zeolite-imidazole-frameworks (ZIF-8). This approach allows formation of Co-N-C for constructing unique structures at meso- and macropore scales, while maintaining microporosity. Density functional theory analysis confirms the superior stability of the Co-N-C catalyst over other M-N-C catalysts (M = Fe, Ni, Cr, and Mn). Furthermore, it reveals that a closed interaction between the Co-N 4 moiety and organic adducts enhances oxophilicity, which prefers a 4-electron ORR activity. The Co-NC catalyst with a developed pore structure shows remarkable durability (6.7% performance degradation for 100 h) and full cell performance in H 2 /O 2 under 1 bar of backpressure (723 mW/cm 2 of maximum power density). Consequently, the unique structure of the synthesized catalyst successfully translates to the computationally-established ORR activity in the half-cell; superior durability is seen in the real device operation and stability analysis. This work is expected to support next-generation fuel cell development. • Melamine encapsulated Co-ZnO-C was prepared as precursor and template for atomic-cluster and porous Co-N-C catalyst. • ma-Co-NC exhibited excellent proton exchange membrane fuel cell performance and stability. • This approach allows formation of M-N-C for constructing unique structures at meso- and macropore scales, while maintaining microporosity.