Oriented epitaxial TiO2 nanowires for water splitting

Wenting Hou, Pablo Cortez, Richard Wuhrer, Sam Macartney, Krassimir N. Bozhilov, Rong Liu, Leigh R. Sheppard, David Kisailus

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Highly oriented epitaxial rutile titanium dioxide (TiO 2) nanowire arrays have been hydrothermally grown on polycrystalline TiO 2 templates with their orientation dependent on the underlying TiO 2 grain. Both the diameter and areal density of the nanowires were tuned by controlling the precursor concentration, and the template surface energy and roughness. Nanowire tip sharpness was influenced by precursor solubility and diffusivity. A new secondary ion mass spectrometer technique has been developed to install additional nucleation sites in single crystal TiO 2 templates and the effect on nanowire growth was probed. Using the acquired TiO 2 nanowire synthesis knowhow, an assortment of nanowire arrays were installed upon the surface of undoped TiO 2 photo-electrodes and assessed for their photo-electrochemical water splitting performance. The key result obtained was that the presence of short and dispersed nanowire arrays significantly improved the photocurrent when the illumination intensity was increased from 100 to 200 mW cm -2. This is attributed to the alignment of the homoepitaxially grown nanowires to the [001] direction, which provides the fastest charge transport in TiO 2 and an improved pathway for photo-holes to find water molecules and undertake oxidation. This result lays a foundation for achieving efficient water splitting under conditions of concentrated solar illumination.
Original languageEnglish
Article number265602
Number of pages9
JournalNanotechnology
Volume28
Issue number26
DOIs
Publication statusPublished - 6 Jun 2017

Bibliographical note

Publisher Copyright:
© 2017 IOP Publishing Ltd.

Keywords

  • chemical templates
  • crystal growth
  • nanowires
  • solubility
  • thermal diffusivity
  • titanium dioxide

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