Design Rules for Oxygen Evolution Catalysis at Porous Iron Oxide Electrodes: A 1000‐Fold Current Density Increase

Nanotubular iron(III) oxide electrodes are optimized for catalytic efficiency in the water oxidation reaction at neutral pH. The nanostructured electrodes are prepared from anodic alumina templates, which are coated with Fe2O3 by atomic layer deposition. Scanning helium ion microscopy, X‐ray diffrac...

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Bibliographic Details
Published in:ChemSusChem 2017-09, Vol.10 (18), p.3644-3651
Main Authors: Haschke, Sandra, Pankin, Dmitrii, Petrov, Yuri, Bochmann, Sebastian, Manshina, Alina, Bachmann, Julien
Format: Article
Language:English
Subjects:
Aluminum oxide
Atomic layer epitaxy
Catalysis
Chemical evolution
Coated electrodes
Current density
Drug Design
Electric Conductivity
Electrochemical impedance spectroscopy
Electrochemistry
Electrodes
Electrolysis
Evolutionary design method
Ferric Compounds - chemistry
Heat treatment
Helium
Hematite
iron
Iron oxides
nanostructures
Oxidation
Oxygen - chemistry
Photochemical Processes
Porosity
Raman spectroscopy
Spectrum analysis
water splitting
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Summary:Nanotubular iron(III) oxide electrodes are optimized for catalytic efficiency in the water oxidation reaction at neutral pH. The nanostructured electrodes are prepared from anodic alumina templates, which are coated with Fe2O3 by atomic layer deposition. Scanning helium ion microscopy, X‐ray diffraction, and Raman spectroscopy are used to characterize the morphologies and phases of samples submitted to various treatments. These methods demonstrate the contrasting effects of thermal annealing and electrochemical treatment. The electrochemical performances of the corresponding electrodes under dark conditions are quantified by steady‐state electrolysis and electrochemical impedance spectroscopy. A rough and amorphous Fe2O3 with phosphate incorporation is critical for the optimization of the water oxidation reaction. For the ideal pore length of 17 μm, the maximum catalytic turnover is reached with an effective current density of 140 μA cm−2 at an applied overpotential of 0.49 V. Rough it up: The efficiency of iron oxide electrodes for electrochemical water oxidation at neutral pH is optimized by macropore structuration, surface roughening, and phosphate incorporation. We use anodic alumina as a macroporous template, atomic layer deposition to coat the pore walls, and electrochemical treatments to increase the surface roughness and incorporate phosphate.
ISSN:1864-5631
1864-564X
DOI:10.1002/cssc.201701068