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Open AccessFeature PaperArticle

Spin-Coated vs. Electrodeposited Mn Oxide Films as Water Oxidation Catalysts

1
Applied Science and Technology Department, Politecnico di Torino, C.so Duca degli Abruzzi 24, Turin 10129, Italy
2
Center for Space Human Robotics, [email protected], Istituto Italiano di Tecnologia, C.so Trento 21, Turin 10129, Italy
3
School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Avenida Brasil 2147, Valparaíso 2362803, Chile
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Academic Editors: Federico Bella and Claudio Gerbaldi
Materials 2016, 9(4), 296; https://doi.org/10.3390/ma9040296
Received: 31 December 2015 / Revised: 11 April 2016 / Accepted: 13 April 2016 / Published: 19 April 2016
(This article belongs to the Special Issue Electrode Materials)
Manganese oxides (MnOx), being active, inexpensive and low-toxicity materials, are considered promising water oxidation catalysts (WOCs). This work reports the preparation and the physico-chemical and electrochemical characterization of spin-coated (SC) films of commercial Mn2O3, Mn3O4 and MnO2 powders. Spin coating consists of few preparation steps and employs green chemicals (i.e., ethanol, acetic acid, polyethylene oxide and water). To the best of our knowledge, this is the first time SC has been used for the preparation of stable powder-based WOCs electrodes. For comparison, MnOx films were also prepared by means of electrodeposition (ED) and tested under the same conditions, at neutral pH. Particular interest was given to α-Mn2O3-based films, since Mn (III) species play a crucial role in the electrocatalytic oxidation of water. To this end, MnO2-based SC and ED films were calcined at 500 °C, in order to obtain the desired α-Mn2O3 crystalline phase. Electrochemical impedance spectroscopy (EIS) measurements were performed to study both electrode charge transport properties and electrode–electrolyte charge transfer kinetics. Long-term stability tests and oxygen/hydrogen evolution measurements were also made on the highest-performing samples and their faradaic efficiencies were quantified, with results higher than 95% for the Mn2O3 SC film, finally showing that the SC technique proposed here is a simple and reliable method to study the electrocatalytic behavior of pre-synthesized WOCs powders. View Full-Text
Keywords: water oxidation; electrodeposition; manganese oxides films; polyethylene oxide; electrochemical impedance spectroscopy water oxidation; electrodeposition; manganese oxides films; polyethylene oxide; electrochemical impedance spectroscopy
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MDPI and ACS Style

Hernández, S.; Ottone, C.; Varetti, S.; Fontana, M.; Pugliese, D.; Saracco, G.; Bonelli, B.; Armandi, M. Spin-Coated vs. Electrodeposited Mn Oxide Films as Water Oxidation Catalysts. Materials 2016, 9, 296.

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