Optimizing the synthesis of Co/Co–Fe nanoparticles/N-doped carbon composite materials as bifunctional oxygen electrocatalysts

• Published in: Electrochimica acta Vol. 318; pp. 281 - 289
• Main Authors: Medina, Danea, Barwe, Stefan, Masa, Justus, Seisel, Sabine, Schuhmann, Wolfgang, Andronescu, Corina
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 20-09-2019; Elsevier BV
• Subjects: Additives; Ammonia; Bifunctional electrocatalyst; Bisphenol A; Carbon; Cobalt; Composite materials; Electrocatalysis; Electrocatalysts; Energy conversion; Energy storage; Heat treatment; Hydroxides; Iron; Nanoparticles; Nitrogen; Optimization; Oxygen evolution reaction; Oxygen evolution reactions; Oxygen reduction reaction; Polybenzoxazine; Polybenzoxazines; Pyrolysis; Reduction; Bifunctional electrocatalyst; Electrocatalysis; Oxygen evolution reaction; Polybenzoxazine; Oxygen reduction reaction
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2019.06.048

A future widespread application of electrochemical energy conversion and storage technologies strongly depends on the substitution of precious metal-based electrocatalysts for the high-overpotential oxygen reduction and oxygen evolution reactions. We report a novel Co/Co–Fe nanoparticles/N-doped carbon composite electrocatalyst (Co/CoxFey/NC) obtained by pyrolysis of CoFe layered double hydroxide (CoFe LDH) embedded in a film of a bisphenol A and tetraethylenepentamine-based polybenzoxazine poly(BA-tepa). During pyrolysis poly(BA-tepa) forms a highly conductive nitrogen-doped carbon matrix encapsulating Co/Co–Fe nanoparticles, thereby circumventing the need of any additional binder material and conductive additives. Optimization with respect to pyrolysis temperature, the CoFe LDH/BA-tepa ratio, as well as of the gas atmosphere used during the thermal treatment was performed. The optimized Co/CoxFey/NC composite material catalyst exhibits remarkable bifunctional activity towards oxygen reduction (ORR) and oxygen evolution (OER) reactions in 0.1 M KOH represented by a potential difference of only 0.77 V between the potentials at which current densities of −1 mA cm−2 for the ORR and 10 mA cm−2 for the OER were recorded. Moreover, the Co/CoxFey/NC composite material pyrolyzed in ammonia atmosphere exhibits promising stability during both the ORR and the OER.