Polyformamidine‐Derived Non‐Noble Metal Electrocatalysts for Efficient Oxygen Reduction Reaction. (16th April 2018)

• Record Type: Journal Article
• Authors: Pardo Pérez, Laura C.; Sahraie, Nastaran Ranjbar; Melke, Julia; Elsässer, Patrick; Teschner, Detre; Huang, Xing; Kraehnert, Ralph; White, Robin J.; Enthaler, Stephan; Strasser, Peter; Fischer, Anna
• Is Part Of: Advanced functional materials. Volume 28:Number 22(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-04-16
• Subjects: electrocatalysts -- fuel cells -- N‐doped carbons -- non‐noble metal catalysts -- ORR -- polyformamidine -- porous materials; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201707551
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: A facile approach for the template‐free synthesis of highly active non‐noble metal based oxygen reduction reaction (ORR) electrocatalysts is presented. Porous Fe−N−C/Fe/Fe3 C composite materials are obtained by pyrolysis of defined precursor mixtures of polyformamidine (PFA) and FeCl3 as nitrogen‐rich carbon and iron sources, respectively. Selection of pyrolysis temperature (700–1100 °C) and FeCl3 loading (5–30 wt%) yields materials with differing surface areas, porosity, graphitization degree, nitrogen and iron content, as well as ORR activity. While the ORR activity of Fe‐free materials is limited (i.e., synthesized from pure PFA), a huge increase in activity is observed for catalysts containing Fe, revealing the participation of the metal dopant in the construction of active electrocatalytic sites. Further activity improvement is achieved via acid‐leaching and repeated pyrolysis, a result which is attributed to the creation of new active sites located at the surface of the porous nitrogen‐doped carbon by dissolution of the Fe and Fe3 C nanophases. The best performing catalyst, which was synthesized with a low Fe loading (i.e., 5 wt%) and at a pyrolysis temperature of 900 °C, exhibits high activity, excellent H2 O selectivity, extended stability, in both basic and acidic media as well as a remarkable tolerance toward methanol. Abstract : The pyrolysis of polyformamidine impregnated by FeCl3 yields a material composition of Fe3 C and N‐doped carbon containing molecularly bound Fe–N x sites. A removal of accessible Fe3 C particles by an acid leaching step yields a highly efficient, methanol‐tolerant, stable, nonprecious‐metal electrocatalyst for the oxygen reduction reaction.