Identification of catalytic sites in cobalt-nitrogen-carbon materials for the oxygen reduction reaction

• DOI: 10.1038/s41467-017-01100-7
• Publication Date: 2017-10-10T19:43:55Z
• Authors: Andrea Zitolo; Nastaran Ranjbar-...; Tzonka Mineva; Jingkun Li; Qingying Jia; Serban Stamatin; George F. Harrington; Stephen Mathew Lyth; Petr Krtil; Sanjeev Mukerjee; Emiliano Fonda; Frédéric Jaouen
• Keywords: Carbon fibers; Oxidation state

Single-atom catalysts with full utilization of metal centers can bridge the gap between molecular and solid-state catalysis. Metal-nitrogen-carbon materials prepared via pyrolysis are promising single-atom but often also comprise metallic particles. Here, we pyrolytically synthesize a Co-N-C material only comprising atomically dispersed cobalt ions identify X-ray absorption spectroscopy, magnetic susceptibility measurements density functional theory structure electronic state three porphyrinic moieties, CoN4C12, CoN3C10,porp CoN2C5. The O2 electro-reduction operando response measured in acidic medium on compared to those Fe-N-C catalyst similarly. We show that moieties unmodified from 0.0 1.0 V versus reversible hydrogen electrode, while Fe-based experience structural electronic-state changes. On basis analysis established relationships redox potential O2-adsorption strength, conclude cobalt-based bind too weakly for efficient reduction.Nitrogen-doped carbon iron or catalytic use. authors have higher potential, oxygen more less active toward reduction than their counterpart, despite similar coordination.