Efficient and stable nanoporous functional composited electrocatalyst derived from Zn/Co-bimetallic zeolitic imidazolate frameworks for oxygen reduction reaction in alkaline media

Abstract

A facile synthesis approach for metal-organic frameworks (MOFs) materials was studied for developing electrocatalysts with high electrochemical catalytic activity and stability. The prepared composite material contains two essential components: a predesigned bimetallic hybrid Zn/Co zeolitic imidazole frameworks (BMZIFs) and N-doped graphitic carbon (NGC) with various contents of carbon nanotubes (CNTs). Among which, NGC@CNTs-40 (100 mg NGC with 40 mg CNTs) exhibits the best oxygen reduction reaction (ORR) performance in alkaline media. In addition, NGC@CNTs-40 shows high surface area of 353.9 m2 g−1, coexisting micro/mesoporous N-doped carbon, low ID/IG ratio and abundant N atomic species. Remarkably, NGC@CNTs-40 exhibited a limiting current density of 5.66 mA cm−2 and a half-wave potential of 0.81 V, which is comparable with commercial Pt/C (5.22 mA cm−2 and 0.81 V) and most reported non-precious metal catalysts. Moreover, NGC@CNTs-40 exhibits better stability than Pt/C. The transferred electron number of NGC@CNTs-40 is 3.92, close to the ideal value of 4.0. The doping of CNTs into MOFs and the synergetic effect of Zn/Co-BMZIFs can enhance the conductivity of conventional MOFs and the blocked transfer of active substances in MOFs crystals, shedding new light on future applications.