Cobalt Single Atoms Immobilized N-Doped Carbon Nanotubes for Enhanced Bifunctional Catalysis toward Oxygen Reduction and Oxygen Evolution Reactions

Novel Co atoms immobilized carbon nanotubes (CoSAs@CNTs) are synthesized by structural engineering of the zeolitic imidazolate framework (ZIF-67) upon treatment with dicyandiamide (DCD). A unique morphology and promising electrochemical performance are shown by the Co atoms immobilized CNTs. The electrocatalyst remarkably exhibits a highly positive onset potential of 0.99 V and half-wave potential of 0.86 V, both even more positive than the commercial Pt/C catalyst, and the current density is also greater than that of the Pt/C catalyst in alkaline media. A decent performance is observed in acidic media also. The electrocatalyst is extraordinarily stable to harsh environments. A promising performance for the oxygen evolution reaction (OER) is demonstrated by the electrocatalyst, while for bifunctional electrocatalysis a small overvoltage of 0.78 V is observed with onset potential at the lower overpotential of 300 mV announcing the advantage of its usage for practical energy conversion and storage systems. This novel study may provide a new road map for fuel cell technology.