An iron oxide photoanode with hierarchical nanostructure for efficient water oxidation

Tae Youl Yang, Ho Young Kang, Kyoungsuk Jin, Sangbaek Park, Ji Hoon Lee, Uk Sim, Hui Yun Jeong, Young Chang Joo, Ki Tae Nam

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)

Abstract

Hematite (α-Fe2O3) has been attracting attention for photoelectrochemical water oxidation due to its visible light photon absorption capacity and high chemical stability, but the short-diffusion length of holes and the large overpotential are still challenging to overcome. Here, in an effort to address these challenges, we develop a hierarchically nanostructured photoanode composed of iron-oxides; Ti-doped hematite nanorods are decorated with an undoped hematite underlayer and β-FeOOH nano-branches. The Ti-doped hematite nanorod array is prepared by hydrothermal synthesis, and this nanostructure offers enhanced separation of photogenerated charges. The underlayer not only increases the photocurrent density but also improves the onset potential. The photocurrent further increases by the epitaxially grown β-FeOOH nano-branches on the hematite, but the onset potential is positively shifted by the β-FeOOH due to increasing flat-band potential. The analyses of the photocurrent transients and electrochemical impedance spectra reveal that β-FeOOH improves the photocurrent by decreasing the resistance to charge transfer through the anode/electrolyte. This study demonstrates a new possibility for improving the efficiency of a hematite photoanode with the interface of other iron-oxides.

Original languageEnglish
Pages (from-to)2297-2305
Number of pages9
JournalJournal of Materials Chemistry A
Volume2
Issue number7
DOIs
Publication statusPublished - 2014 Feb 21
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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