Engineering Nanoporous Iron(III) Oxide into an Effective Water Oxidation Electrode

Sandra Haschke, Yanlin Wu, Muhammad Bashouti, Silke Christiansen, Julien Bachmann

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

The geometric effects of nanostructuring a pure Fe2O3 surface on its electrochemical water oxidation performance at neutral pH were systematically explored. Atomic layer deposition was used to coat the inner walls of cylindrical "anodic" nanopores ordered in parallel arrays with a homogeneous Fe2O3 layer. Annealing and electrochemical treatments generated a roughened surface, as demonstrated by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy, the larger geometric area of which increases current densities. Combining these treatments with the "anodic" pore geometry delivered an effective increase in turnover by almost three orders of magnitude with respect to a smooth, planar Fe2O3 surface. However, the current density depended on the pore length in a non-monotonic manner. An optimal length was found that maximized turnover by equating the rate of transport in the electrolyte with that of charge transfer across the interface. Pore your heart out: Geometry influences the electrochemical water oxidation performance of nanostructured Fe2O3 surfaces systematically. Ordered arrays of cylindrical "anodic" nanopores coated with Fe2O3 by atomic layer deposition deliver an effective increase in turnover by up to three orders of magnitude with respect to a smooth, planar surface. The current density is maximized if the timescales of turnover at the interface and transport towards it are equated.

Original languageEnglish
Pages (from-to)2455-2459
Number of pages5
JournalChemCatChem
Volume7
Issue number16
DOIs
StatePublished - 1 Aug 2015
Externally publishedYes

Keywords

  • atomic layer deposition
  • electrochemistry
  • iron oxide
  • mesoporous materials
  • oxygen evolution reaction

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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