Design aspects of all atomic layer deposited TiO2–Fe2O3 scaffold-absorber photoanodes for water splitting

Arto Hiltunen, Tero-Petri Ruoko, Tomi Iivonen, Kimmo Lahtonen, Harri Ali-Löytty, Essi Sarlin, Mika Valden, Markku Leskelä, Nikolai Tkachenko

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Iron and titanium oxides have attracted substantial attention in photoelectrochemical water splitting applications. However, both materials suffer from intrinsic limitations that constrain the final device performance. In order to overcome the limitations of the two materials alone, their combination has been proposed as a solution to the problems. Here we report on the fabrication of an atomic layer deposited (ALD) Fe2O3 coating on porous ALD-TiO2. Our results show that successful implementation requires complete mixing of the TiO2 and Fe2O3 layers via annealing resulting in the formation of a photoactive iron titanium oxide on the surface. Moreover, we found that incomplete mixing leads to crystallization of Fe2O3 to hematite that is detrimental to the photoelectrochemical performance. IPCE and transient photocurrent measurements performed using UV and visible light excitation confirmed that the iron titanium oxide extends the photocurrent generation to the visible range. These measurements were complemented by transient absorption spectroscopy (TAS), which revealed a new band absent in pristine hematite or anatase TiO2 that we assign to charge transfer within the structure. Taken together, these results provide design guidelines to be considered when aiming to combine TiO2 and Fe2O3 for photoelectrochemical applications.
Original languageEnglish
JournalSustainable Energy & Fuels
Volume2
Issue number9
Pages (from-to)2124-2130
Number of pages7
ISSN2398-4902
DOIs
Publication statusPublished - 1 Sep 2018
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 116 Chemical sciences
  • PHOTOELECTROCHEMICAL CELLS
  • NANOTUBE ARRAYS
  • HEMATITE FILMS
  • OXIDATION
  • TIO2
  • ALPHA-FE2O3
  • PHOTOCURRENT

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