Conductive bimetal organic framework nanorods decorated with highly dispersed Co3O4 nanoparticles as bi-functional electrocatalyst

Abstract

The poor electronic conductivity and low intrinsic electrocatalytic activity of metal organic frameworks (MOFs) greatly limit their direct application in electrocatalytic reactions. Herein, we report a conductive two-dimensional π–d conjugated Ni and Co bimetal organic framework (MOF)—NiCo-(2,3,6,7,10,11-hexaiminotriphenylene) (NiCo-HITP) nanorods decorated with highly dispersed Co3O4 nanoparticles (NPs) as a promising bi-functional electrocatalyst towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through an effective and facile strategy by modifying the rod-shaped -Ni3HITP2 crystals using cobalt ions. The triggered electrocatalytic activity of the resulting MOF-based materials was achieved by increasing the electrical conductivity (7.23 S cm−1) originated from Ni3HITP2 substrate and also by creating the cooperative catalysis sites of Co–N x and Co3O4 NPs. Optimized syntheses show a promising ORR activity with a high half-wave potential (0.77 V) and also a significantly improved OER activity compared with pure Ni3HITP2 in alkaline electrolyte. Furthermore, a rechargeable Zn–air battery using the as-prepared material as air-cathode also shows a high power density (143.1 mW cm−2)—even comparable to a commercial Pt/C-RuO2-based battery. This methodology offers a new prospect in the design and synthesis of non-carbonized MOF bi-functional electrocatalysts for efficient catalysis towards ORR and OER.