α-Fe2O3/TiO2 3D hierarchical nanostructures for enhanced photoelectrochemical water splitting

Hyungkyu Han, Francesca Riboni, Frantisek Karlicky, Stepan Kment, Anandarup Goswami, Pitchaimuthu Sudhagar, Jeongeun Yoo, Lei Wang, Ondrej Tomanec, Martin Petr, Ondrej Haderka, Chiaki Terashima, Akira Fujishima, Patrik Schmuki, Radek Zboril

Research output: Contribution to journalArticlepeer-review

83 Citations (Scopus)

Abstract

We report the fabrication of 3D hierarchical hetero-nanostructures composed of thin α-Fe2O3 nanoflakes branched on TiO2 nanotubes. The novel α-Fe2O3/TiO2 hierarchical nanostructures, synthesized on FTO through a multi-step hydrothermal process, exhibit enhanced performances in photo-electrochemical water splitting and in the photocatalytic degradation of an organic dye, with respect to pure TiO2 nanotubes. An enhanced separation of photogenerated charge carriers is here proposed as the main factor for the observed photo-activities: electrons photogenerated in TiO2 are efficiently collected at FTO, while holes are transferred to the α-Fe2O3 nanobranches that serve as charge mediators to the electrolyte. The morphology of α-Fe2O3 that varies from ultrathin nanoflakes to nanorod/nanofiber structures depending on the Fe precursor concentration was shown to have a significant impact on the photo-induced activity of the α-Fe2O3/TiO2 composites. In particular, it is shown that for an optimized photo-electrochemical structure, a combination of critical factors should be achieved such as (i) TiO2 light absorption and photo-activation vs. α-Fe2O3-induced shadowing effect and (ii) the availability of free TiO2 surface vs. α-Fe2O3-coated surface. Finally, theoretical analysis, based on DFT calculations, confirmed the optical properties experimentally determined for the α-Fe2O3/TiO2 hierarchical nanostructures. We anticipate that this new multi-step hydrothermal process can be a blueprint for the design and development of other hierarchical heterogeneous metal oxide electrodes suitable for photo-electrochemical applications.

Original languageEnglish
Pages (from-to)134-142
Number of pages9
JournalNanoscale
Volume9
Issue number1
Early online date2 Nov 2016
DOIs
Publication statusPublished - 7 Jan 2017

ASJC Scopus subject areas

  • Materials Science(all)

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