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Photocatalytic, structural and optical properties of mixed anion solid solutions Ba3Sc2-xInxO5Cu2S2 and Ba3In2O5Cu2S2-ySey

Photocatalytic, structural and optical properties of mixed anion solid solutions Ba3Sc2-xInxO5Cu2S2 and Ba3In2O5Cu2S2-ySey
Photocatalytic, structural and optical properties of mixed anion solid solutions Ba3Sc2-xInxO5Cu2S2 and Ba3In2O5Cu2S2-ySey
Nine members of two contiguous solid solutions, Ba3Sc2−xInxO5Cu2S2 and Ba3In2O5Cu2S2−ySey (x, y = 0, 0.5, 1, 1.5 and 2), were synthesised at temperatures between 800 °C and 900 °C by stoichiometric combination of binary precursors. Their structures were determined by Rietveld refinement of X-ray powder diffraction data and found to adopt the SmNi3Ge3 structure with I4/mmm symmetry. Approximate Vegard law relationships were found within each solution between the lattice parameters and composition, with an observed cell volume of 466.4 Å3 for Ba3Sc2O5Cu2S2 increasing to 481.0 Å3 for Ba3In2O5Cu2S2 and finally to 499.0 Å3 for Ba3In2O5Cu2Se2. In the first solid solution, this volume increase is driven by the replacement of scandium by the larger indium ion, generating increased strain in the copper chalcogenide layer. In the second solution the substitution into the structure of the larger selenium drives further volume expansion, while relieving the strain in the copper chalcogenide layer. Band gaps were estimated from reflectance spectroscopy and these were determined to be 3.3 eV, 1.8 eV, and 1.3 eV for the three end members Ba3Sc2O5Cu2S2, Ba3In2O5Cu2S2, and Ba3Sc2In2O5Cu2Se2, respectively. For the intermediate compositions a linear relationship between band gap size and composition was observed, driven in the first solution by the introduction of the more electronegative indium lowering the conduction band minimum and in the second solution by the substitution of the electropositive selenium raising the valance band maximum. Photocatalytic activity was observed in all samples under solar simulated light, based on a dye degradation test, with the exception of Ba3In2O5Cu2Se1.5S0.5. The most active sample was found to be Ba3Sc2O5Cu2S2, the material with the largest band gap.
2050-7488
19887-19897
Hyett, Geoffrey
4f292fc9-2198-4b18-99b9-3c74e7dfed8d
Limburn, Gregory James
afd49e4c-1afa-4c37-b608-fa0581d380f7
Iborra Torres, Antonio
231fb0fc-78fd-40ea-9ebd-0bb0c6131e71
Scanlon, David O.
23dbcc36-0b42-40dc-a3af-64c8bad7beb3
Williamson, Benjamin
ed9fcfca-1cfc-44c3-b4af-dca0b60c8a04
Stephens, Matthew
e45d137d-4701-43d9-8c8f-8c51da35adc9
Hyett, Geoffrey
4f292fc9-2198-4b18-99b9-3c74e7dfed8d
Limburn, Gregory James
afd49e4c-1afa-4c37-b608-fa0581d380f7
Iborra Torres, Antonio
231fb0fc-78fd-40ea-9ebd-0bb0c6131e71
Scanlon, David O.
23dbcc36-0b42-40dc-a3af-64c8bad7beb3
Williamson, Benjamin
ed9fcfca-1cfc-44c3-b4af-dca0b60c8a04
Stephens, Matthew
e45d137d-4701-43d9-8c8f-8c51da35adc9

Hyett, Geoffrey, Limburn, Gregory James, Iborra Torres, Antonio, Scanlon, David O., Williamson, Benjamin and Stephens, Matthew (2020) Photocatalytic, structural and optical properties of mixed anion solid solutions Ba3Sc2-xInxO5Cu2S2 and Ba3In2O5Cu2S2-ySey. Journal of Materials Chemistry A, 8 (38), 19887-19897. (doi:10.1039/D0TA06629J).

Record type: Article

Abstract

Nine members of two contiguous solid solutions, Ba3Sc2−xInxO5Cu2S2 and Ba3In2O5Cu2S2−ySey (x, y = 0, 0.5, 1, 1.5 and 2), were synthesised at temperatures between 800 °C and 900 °C by stoichiometric combination of binary precursors. Their structures were determined by Rietveld refinement of X-ray powder diffraction data and found to adopt the SmNi3Ge3 structure with I4/mmm symmetry. Approximate Vegard law relationships were found within each solution between the lattice parameters and composition, with an observed cell volume of 466.4 Å3 for Ba3Sc2O5Cu2S2 increasing to 481.0 Å3 for Ba3In2O5Cu2S2 and finally to 499.0 Å3 for Ba3In2O5Cu2Se2. In the first solid solution, this volume increase is driven by the replacement of scandium by the larger indium ion, generating increased strain in the copper chalcogenide layer. In the second solution the substitution into the structure of the larger selenium drives further volume expansion, while relieving the strain in the copper chalcogenide layer. Band gaps were estimated from reflectance spectroscopy and these were determined to be 3.3 eV, 1.8 eV, and 1.3 eV for the three end members Ba3Sc2O5Cu2S2, Ba3In2O5Cu2S2, and Ba3Sc2In2O5Cu2Se2, respectively. For the intermediate compositions a linear relationship between band gap size and composition was observed, driven in the first solution by the introduction of the more electronegative indium lowering the conduction band minimum and in the second solution by the substitution of the electropositive selenium raising the valance band maximum. Photocatalytic activity was observed in all samples under solar simulated light, based on a dye degradation test, with the exception of Ba3In2O5Cu2Se1.5S0.5. The most active sample was found to be Ba3Sc2O5Cu2S2, the material with the largest band gap.

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Accepted/In Press date: 9 September 2020
e-pub ahead of print date: 10 September 2020
Published date: 15 September 2020

Identifiers

Local EPrints ID: 444038
URI: http://eprints.soton.ac.uk/id/eprint/444038
ISSN: 2050-7488
PURE UUID: 3c6351d4-d0b8-43e7-907e-015b1030b91e
ORCID for Geoffrey Hyett: ORCID iD orcid.org/0000-0001-9302-9723

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Date deposited: 23 Sep 2020 16:31
Last modified: 17 Mar 2021 02:44

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