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Electrodeposited MnO x Films from Ionic Liquid for Electrocatalytic Water Oxidation
Author(s) -
Zhou Fengling,
Izgorodin Alexey,
Hocking Rosalie K.,
Spiccia Leone,
MacFarlane Douglas R.
Publication year - 2012
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201100783
Subject(s) - materials science , catalysis , birnessite , electrolyte , inorganic chemistry , manganese , chemical engineering , tin oxide , oxide , x ray absorption spectroscopy , ionic liquid , absorption spectroscopy , electrode , manganese oxide , chemistry , biochemistry , physics , quantum mechanics , engineering , metallurgy
A novel method for the electrodeposition of highly active water oxidation catalysts is described. The manganese oxide (MnO x ) films are electrodeposited on fluorine tin oxide (FTO) glass substrate at high temperature (120 °C) from an ionic liquid electrolyte (ethylammonium nitrate). A range of analytical techniques, including X‐ray absorption spectroscopy (XAS), X‐ray diffraction (XRD), and energy‐dispersive X‐ray analyzer (EDX), indicate that the valence state of manganese in the deposited films can be controlled by changing the electrolyte composition. Along with the different phase compositions, a number of different morphologies including nanowires, nanoparticles, nanofibers as well as highly open and dense structures are obtained by varying the acidity of the electrolyte. The effect of morphology and chemical composition on the catalytic activity towards water oxidation is investigated. The film composed of Mn 3 O 4 shows low catalytic activities, while the films composed of birnessite‐like manganese oxide phase and Mn 2 O 3 exhibit high catalytic activities for water oxidation. The catalytic activities are also affected by the surface morphology, i.e., a higher surface area and more open structure shows a higher catalytic activity. High rates of oxygen production are observed from MnO x films prepared in a neutral electrolyte.