MOF-199-Based Nitrogen-Doped Bimetal Cathode Catalyst for Anion Exchange Membrane Fuel Cells

This study investigates a metal-organic framework MOF-199-based catalyst subjected to postsynthetic modification and heat treatment to enhance its catalytic activity for the oxygen reduction reaction (ORR) in an alkaline environment. The MOF-199, which has a copper metal center and is modified with iron and nitrogen, exhibits an onset potential (E_onset) of 0.99 V and a half-wave potential (E_1/2) of 0.846 V with an electron transfer number of 3.997 at 0.3 V. MOF-199-based nitrogen-doped bimetal catalysts in the anion-exchange membrane fuel cell (AEMFC) perform nearly as well as platinum catalysts, underscoring the catalyst’s proficiency in ORR. The metal active sites of the catalyst consist of Cu²⁺ and Fe⁰, and from d-band center analysis, the iron site acts as an O₂ adsorber and activates the oxygen. The copper site with a lower d-band center can help release the intermediate and avoid overbinding with the metal site. Nitrogen-doped carbon support also augments the active site to enhance catalytic activity and performance in anion-exchange membrane fuel cells.