Iron-/Nitrogen-Doped Electrocatalytically Active Carbons for the Oxygen Reduction Reaction with Low Amounts of Cobalt

Transition-metal-doped carbon catalysts are promising Pt-free alternatives for low-temperature fuel cells. They are frequently obtained from sacrificial N-rich zeolitic imidazolate frameworks (ZIFs) doped with Co and Fe. The optimal low loading of metals has to be achieved to guarantee the competitive efficiency and facilitate an inquiry into the mechanism of their catalytic activity. We report on microwave-assisted solvothermal synthesis of Zn,Co-ZIFs with a relatively low (1-15 mol %) Co loading, which were further enriched with Fe(II). Materials were pyrolyzed at 700 °C to form catalytically active carbons bearing metal nanoparticles confined in structured carbon. The electrochemistry test of carbons for the oxygen reduction reaction (ORR) in perchloric acid demonstrated their high efficiency even at low cobalt contents. The initial loading of 10 mol % was found efficient, leading to the production of catalytically active carbons allowing for four-electron path of ORR.