Abstract
The photoelectrochemical properties of polycrystalline GaFeO3 (GFO) thin films are investigated for the first time. Thin-films prepared by sol-gel methods exhibit phase-pure orthorhombic GFO with the Pc21n space group, as confirmed by XRD and Raman spectroscopy. Optical responses are characterized by a 2.72 eV interband transition and sub-bandgap d-d transitions associated with octahedral and tetrahedral coordination of Fe3+ sites. DFT-HSE06 electronic structure calculations show GFO is highly ionic with very low dispersion in the valence band maximum (VBM) and conduction band minima (CBM). Electrochemical impedance spectroscopy reveals n-type conductivity with a flat band potential (Ufb) of 0.52 V vs RHE, indicating that GFO has the most positive CBM reported of any ferrite. The photoelectrochemical oxidation of SO32- shows an ideal semiconductor-electrolyte interfacial behavior with no evidence of surface recombination down to the Ufb. Surprisingly, the onset potential for the oxygen evolution reaction also coincides with the Ufb, showing interfacial hole-transfer efficiency above 50%. The photoelectrochemical properties are limited by bulk recombination due to the short-diffusion length of minority carriers as well as slow transport of majority carriers. Strategies towards developing high-efficiency GFO photoanodes are briefly discussed.
Original language | English |
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Article number | 2002784 |
Number of pages | 9 |
Journal | Advanced Energy Materials |
Volume | 10 |
Issue number | 45 |
Early online date | 22 Oct 2020 |
DOIs | |
Publication status | E-pub ahead of print - 22 Oct 2020 |
Keywords
- GaFeO3
- photoelectrodes
- oxygen evolution reaction
- surface recombination
- carrier transport
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High Interfacial Hole-Transfer Efficiency at GaFeO3 Thin Film Photoanodes
Fermin, D. (Creator), University of Bristol, 9 Oct 2020
DOI: 10.5523/bris.c4w8vwn8xfr2kozw9k8lb7o1, http://data.bris.ac.uk/data/dataset/c4w8vwn8xfr2kozw9k8lb7o1
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Profiles
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Professor David J Fermin
- School of Chemistry - Professor of Electrochemistry
- Cabot Institute for the Environment
- Materials for Energy
- Soft Matter, Colloids and Materials
Person: Academic , Member