Electrospun metal-organic framework nanoparticle fibers and their derived electrocatalysts for oxygen reduction reaction

The rational design of assembled metal-organic frameworks (MOFs) derived carbon materials with rapid mass transport properties and stable porous structure is highly desirable yet a great challenge to date. In this work, MOFs-derived Co/N-doped porous carbon fibers with high electrochemical performance can be prepared simply by carbonizing MOFs nanofibers, which were fabricated by the electrospinning-assisted assembly of bimetallic zeolitic imidazolate framework nanoparticles (BMZIFs) based on ZIF-8 and ZIF-67. The effects of assembly and Zn/Co ratios on the oxygen reduction reaction (ORR) performances of the electrospun fibers derivatives were systematically studied. As expected, compared to the non-electrospun samples, such doped porous carbon nanofibers exhibited excellent electrocatalytic performances without any etching or other activating processes, and the sample with the molar ratio of Zn: Co= 5:1 even showed comparable ORR performance with the commercial Pt/C catalyst under the same conditions. The high catalytic performances root in the dense assembly of MOFs within the electrospun fibers, which was beneficial to endow the derivatives with the high surface area as well as uniform N and Co doping. Besides, the one-dimensional porous structure significantly promoted the mass transfer and exposure of active sites.