Low temperature atomic layer deposition of highly photoactive hematite using iron(iii) chloride and water
Nanostructured hematite (α-Fe2O3) has been widely studied for use in a variety of thin film applications including solar energy conversion, water oxidation, catalysis, lithium-ion batteries, and gas sensing. Among established deposition methods, atomic layer deposition (ALD) is a leading technique for controlled synthesis of a wide range of nanostructured materials. In this work, ALD of Fe2O3 is demonstrated using FeCl3 and H2O precursors at growth temperatures between 200 and 350 °C. Self-limiting growth of Fe2O3 is demonstrated with a growth rate of ~0.6 Å per cycle. As-deposited, films are nanocrystalline with low chlorine impurities and a mixture of α- and γ-Fe2O3. Post-deposition annealing in O2 leads to phase-pure α-Fe2O3 with increased out-of-plane grain size. Photoelectrochemical measurements under simulated solar illumination reveal high photoactivity toward water oxidation in both as-deposited and post-annealed films. Planar films deposited at low temperature (235 °C) exhibit remarkably high photocurrent densities ~0.71 mA cm-2 at 1.53 V vs. the reversible hydrogen electrode (RHE) without further processing. Films annealed in air at 500 °C show current densities of up to 0.84 mA cm-2 (1.53 V vs. RHE).
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science - Office of High Energy Physics
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1395080
- Journal Information:
- Journal of Materials Chemistry. A, Vol. 1, Issue 38; ISSN 2050-7488
- Publisher:
- Royal Society of Chemistry
- Country of Publication:
- United States
- Language:
- English
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