Nitrogen-doped carbon nanotubes decorated with cobalt nanoparticles derived from zeolitic imidazolate framework-67 for highly efficient oxygen reduction reaction electrocatalysis

Abstract

Nitrogen-doped carbon nanotubes decorated with carbon-coated cobalt nanoparticles (Co@C-NCNTs) are constructed from the zeolitic imidazolate framework ZIF-67. Electrostatic force-induced preadsorption of coordination center ions on the surface of halloysite nanotubes leads to confined nucleation and in situ growth of a thin layer of ZIF-67. Subsequent carbonization and template removal give rise to NCNTs with open end and large inner cavity, thin wall moderate graphitization, and decoration with carbon-coated Co nanoparticles. The synthetic strategy can be easily extended to the preparation of various NCNTs with tunable graphitization and metal decoration from different ZIFs. Benefited from one-dimensional nanotubes with more exposed active surface area and convenient channels for the transport of electrons and reactants, the resulting Co@C-NCNTs exhibit enhanced catalytic performance in oxygen reduction reaction with an onset potential of −0.1 V vs Ag/AgCl, high current density (−4.42 mA/cm2 at −0.6 V), and approximate 4e− transfer process in O2-saturated 0.1 M KOH. The Co@C-NCNTs have higher durability and remarkable methanol tolerance capability both in alkaline and acidic solutions superior to the commercial Pt/C. The present strategy for structure-control electrocatalysts creates a new pathway for the fabrication of promising cathode catalyst for fuel cell applications.