Cobalt/nitrogen-Co-doped nanoscale hierarchically porous composites derived from octahedral metal-organic framework for efficient oxygen reduction in microbial fuel cells

Microbial fuel cell, a promising energy conversion technology, plays a crucial role in the field of renewable and sustainable energy. In an air-cathode microbial fuel cell, the oxygen reduction reaction catalytic activity of cathode catalyst is a critical factor that determines the performance of microbial fuel cell. This work reports a facile route for the synthesis of Co/N incorporated carbonaceous electrocatalyst using a Zr-based metal-organic framework UiO66-NH₂ as a template. This electrocatalyst exhibits outstanding activity and stability toward four-electron mechanism. In the microbial fuel cell application, Co/UiO66-900 shows superb electrochemical performance with a stable output voltage of 395 mV and maximum power density of 299.62 mW/m², which is 95.8% of the power density achieved in microbial fuel cell catalyzed by Pt/C catalyst (312.59 mW/m²). Co/UiO66-900 possesses high-performance catalytic activity because of its 3D-structured micropores, nitrogen-coordinated cobalt species and the synergistic effects between carbon and metal ion center. These unique properties can facilitate the oxygen reduction reaction by exposing abundant efficient active sites and accelerating mass transfer at oxygen reduction reaction interfaces. This work suggests that Co/UiO66-900 catalyst with superb electrocatalytic ORR activity is a promising alternative which can replace the expensive Pt/C in air-cathode MFC.