Co/N-doped carbon nanotube arrays grown on 2D MOFs-derived matrix for boosting the oxygen reduction reaction in alkaline and acidic media

Abstract

The development of high-performance and cost-effective electrocatalysts towards oxygen reduction reaction (ORR) is of significant importance, but still challenging for the practical applications in related energy systems. ORR process typically suffers from sluggish kinetics, the exploration of ORR electrocatalyst thus requires elaborate design. Herein, an effective strategy is developed for growing Co/N-doped carbon nanotube arrays on 2D MOFs-derived matrix via the pyrolysis of Co/Zn metal-organic-framework (MOF) nanosheets. The Co/Zn-MOF nanosheets serve as both the self-template for the 2D carbonized framework morphology and C/N source for the in-situ growth of 1D N-doped carbon nanotubes. The constructed hierarchical architecture effectively integrates the 0D/1D Co nanoparticle/N-doped carbon nanotube interface and 1D (nanotubes)/2D (nanosheets) junction into frameworks with highly exposed active surface, enhanced mass-transport kinetics and electrical conductivity. As a result, the designed composite exhibits superior ORR activity and durability in alkaline media as compared to commercial Pt/C. Particularly, it shows promising ORR performance with a half-wave potential of 0.78 V versus reversible hydrogen electrode and negligible activity attenuation after 5000 potential cycles in acidic electrolyte. The designed strategy can be extended to construct other MOFs-derived carbon matrixes with diverse hierarchical structures and provide an efficient avenue for searching high-performance electrocatalysts.