Nickel-Cobalt Metal-Organic Framework CPO-27 and g-C₃N₄ for Oxygen Reduction Reaction in Alkaline-Exchange-Membrane Fuel Cell

This study synthesizes the nickel-cobalt supported by the metal-organic framework CPO-27 (coordination polymer of Oslo, Ni-Co-CPO-27) and g-C₃N₄, showing outstanding catalytic activity and stability for oxygen reduction reaction in alkaline media, notated by NiCo₂-CPO-27/PCN-HT (PCN-HT: heat-treated polymeric carbon nitrite). The half-wave potential of NiCo₂-CPO-27/PCN-HT is 0.82 V, and the electron transfer number is around 3.99, which is close to the activity of Pt/C. The stability test of NiCo₂-CPO-27/PCN-HT demonstrates only 0.01 V decade of the half-wave potential after 30,000 cycles. The synergistic effects of Ni-Co metals, pyridinic-N species, and graphitic-N species contribute to the outstanding performance of NiCo₂-CPO-27/PCN-HT. The anion exchange membrane fuel cell (AEMFC) using NiCo₂-CPO-27/PCN-HT in the cathode shows excellent performance with a maximum power density of 224.4 mW cm^-2, 20% higher than AEMFC using the Pt/C under the same condition.