Cobalt hexacyanoferrate as a selective and high current density formate oxidation electrocatalyst
Han, Lijuan (Institut Català d'Investigació Química)
González-Cobos, Jesús (Institut de Ciència i Tecnologia de Barcelona)
Sánchez-Molina, Irene (Institut Català d'Investigació Química)
Giancola, Stefano (Institut Català d'Investigació Química)
Folkman, Scott J. (Institut de Ciència i Tecnologia de Barcelona)
Tang, PengYi (Institut Català de Nanociència i Nanotecnologia)
Heggen, Marc (Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (Jülich, Alemanya))
Dunin-Borkowski, Rafal E. (Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (Jülich, Alemanya))
Arbiol i Cobos, Jordi (Institut Català de Nanociència i Nanotecnologia)
Giménez, Sixto (Universitat Jaume I. Institute of Advanced Materials)
Galán-Mascarós, José Ramón (Institut Català d'Investigació Química)

Data:	2020
Resum:	Herein we report the selectivity, stability, and electrochemical characterization of cobalt hexacyanoferrate, the Co-Fe Prussian Blue derivative (CoFePB), as a formate/formic acid oxidation electrocatalyst in aqueous media. CoFePB is able to quantitatively catalyze (100% Faradaic efficiency within less than 8% standard error at pH 5) the electrochemical oxidation of formate to CO2 over a pH range of 1-13. This quantitative formate elecrooxidation is possible due to the exclusive selectivity of the catalyst in a wide potential window (from ca. 1. 2 to 1. 7 V vs RHE), where no other substrate in aqueous conditions is activated: neither other organic molecules, such as alcohols or acids, nor water itself. CoFePB is one of the first heterogeneous noble-metal-free catalysts reported for the electrooxidation of small hydrocarbon molecules. Importantly, the catalyst showed a very high tolerance against surface poisoning during the reaction, as supported by the cyclic voltammetry and electrochemical impedance spectroscopy data, thereby allowing CoFePB to operate at greater current density than state-of-the-art noble metal catalysts. For example, we observed that CoFePB is able to achieve a formate oxidation current ∼10 mA cm-2 at pH 5, 0. 4 M formate at 1. 4 V vs RHE, whereas a Pt disk and Pd(5%)/C electrodes had currents of 0. 4 and 1. 4 mA cm-2, respectively, under identical conditions. The remarkable selectivity, stability, and high current density of CoFePB, in contrast to state-of-the-art catalysts based on platinum-group metals, is an important step in the search for inexpensive earth-abundant materials for oxidation of organic molecules for use in liquid fuel cells or for selective organic molecule sensors. Furthermore, because CoFePB is not poisoned by intermediates and can achieve higher current density than Pt or Pd, improvement of the catalyst onset potential can lead to higher power density formate oxidation fuel cells using earth-abundant metals than with Pt or Pd.
Ajuts:	European Commission 754510 Ministerio de Ciencia e Innovación RTI2018-095618-B-I00 Ministerio de Ciencia e Innovación ENE2017-85087-C3 Ministerio de Economía y Competitividad SEV-2017-0706 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1246 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-327
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió sotmesa a revisió
Matèria:	Catalysts ; Electrical properties ; Electrodes ; Oxidation ; Platinum
Publicat a:	ACS Applied Energy Materials, Vol. 3, issue 9 (Sep. 2020) , p. 9198-9207, ISSN 2574-0962

DOI: 10.1021/acsaem.0c01548

Preprint 13 p, 1.0 MB

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