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

0481079 - ÚFCH JH 2018 RIV GB eng J - Journal Article
Zitolo, A. - Ranjbar-Sahraie, N. - Mineva, T. - Li, J. - Jia, J. - Stamatin, Serban - Harrington, G. F. - Lyth, S. M. - Krtil, Petr - Mukerjee, S. - Fonda, E. - Jaouen, F.
Identification of catalytic sites in cobalt-nitrogen-carbon materials for the oxygen reduction reaction.
Nature Communications. Roč. 8, č. 1 (2017), č. článku 957. E-ISSN 2041-1723
Institutional support: RVO:61388955
Keywords : ray-absorption spectroscopy * density-functional theory * body distribution-functions * electrolyte fuel-cells
OECD category: Physical chemistry
Impact factor: 12.353, year: 2017
Method of publishing: Open access

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 catalysts but often also comprise metallic particles. Here, we pyrolytically synthesize a Co-N-C material only comprising atomically dispersed cobalt ions and identify with X-ray absorption spectroscopy, magnetic susceptibility measurements and density functional theory the structure and electronic state of three porphyrinic moieties, CoN4C12, CoN3C10,(porp) and CoN2C5. The O-2 electro-reduction and operando X-ray absorption response are measured in acidic medium on Co-N-C and compared to those of a Fe-N-C catalyst prepared similarly. We show that cobalt moieties are unmodified from 0.0 to 1.0 V versus a reversible hydrogen electrode, while Fe-based moieties experience structural and electronic-state changes. On the basis of density functional theory analysis and established relationships between redox potential and O-2-adsorption strength, we conclude that cobaltbased moieties bind O-2 too weakly for efficient O-2 reduction.
Permanent Link: http://hdl.handle.net/11104/0276689