A CNT Intercalated Co Porphyrin-Based Metal Organic Framework Catalyst for Oxygen Reduction Reaction

The poor electronic conductivity of metal-organic framework (MOF) materials hinders their direct application in the field of electrocatalysis in fuel cells. Herein, we proposed a strategy of embedding carbon nanotubes (CNTs) during the growth process of MOF crystals, synthesizing a metalloporphyrin-based MOF catalyst TCPPCo-MOF-CNT with a unique CNT-intercalated MOF structure. Physical characterization revealed that the CNTs enhance the overall conductivity while retaining the original characteristics of the MOF and metalloporphyrin. Simultaneously, the insertion of CNTs generated adequate mesopores and created a hierarchical porous structure that enhances mass transfer efficiency. X-ray photoelectron spectroscopic analysis confirmed that the C atom in CNT changed the electron cloud density on the catalytic active center Co, optimizing the electronic structure. Consequently, the E_1/2 of the TCPPCo-MOF-CNT catalyst under neutral conditions reached 0.77 V (vs. RHE), outperforming the catalyst without CNTs. When the TCPPCo-MOF-CNT was employed as the cathode catalyst in assembling microbial fuel cells (MFCs) with Nafion-117 as the proton exchange membrane, the maximum power density of MFCs reached approximately 500 mW·m^–2.