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Combinatorial Discovery of Lanthanum-Tantalum Oxynitride Solar Light Absorbers with Dilute Nitrogen for Solar Fuels Applications

Suram, Santosh K. and Fackler, Sean W. and Zhou, Lan and N'Diaye, Alpha T. and Drisdell, Walter S. and Yano, Junko and Gregoire, John M. (2018) Combinatorial Discovery of Lanthanum-Tantalum Oxynitride Solar Light Absorbers with Dilute Nitrogen for Solar Fuels Applications. ACS Combinatorial Science, 20 (1). pp. 26-34. ISSN 2156-8952. doi:10.1021/acscombsci.7b00143.

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Oxynitrides with the photoelectrochemical stability of oxides and desirable band energetics of nitrides comprise a promising class of materials for solar photochemistry. Challenges in synthesizing a wide variety of oxynitride materials has limited exploration of this class of functional materials, which we address using a reactive cosputtering combined with rapid thermal processing method to synthesize multi-cation–multi-anion libraries. We demonstrate the synthesis of a La_xTa_(1–x)O_yN_z thin film composition spread library and its characterization by both traditional thin film materials characterization and custom combinatorial optical spectroscopy and X-ray absorption near edge spectroscopy (XANES) techniques, ultimately establishing structure-chemistry-property relationships. We observe that over a substantial La–Ta composition range the thin films crystallize in the same perovskite LaTaON2 structure with significant variation of anion chemistry. The relative invariance in optical band gap demonstrates a remarkable decoupling of composition and band energetics so that the composition can be optimized while retaining the desirable 2 eV band gap energy. We also demonstrate the intercalation of diatomic nitrogen into the La_3TaO_7 structure, which gives rise to a direct-allowed optical transition at 2.2 eV, less than half the value of the oxide’s band gap. These findings motivate further exploration of the visible light response of this material that is predicted to be stable over a wide range of electrochemical potential.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Suram, Santosh K.0000-0001-8170-2685
Zhou, Lan0000-0002-7052-266X
Drisdell, Walter S.0000-0002-8693-4562
Yano, Junko0000-0001-6308-9071
Gregoire, John M.0000-0002-2863-5265
Additional Information:© 2017 American Chemical Society. Received: September 29, 2017; Revised: November 20, 2017; Published: November 27, 2017. This study is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy (Award No. DE-SC0004993). The authors thank Dr. Chi Ma and Prof. George R. Rossman for assistance with WDS measurements. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. The authors also thank Yi-Sheng Liu, Li Cheng Kao, and Yifan Ye for assistance with XANES measurements at ALS beamline The authors declare no competing financial interest.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0004993
Department of Energy (DOE)DE-AC02-05CH11231
Subject Keywords:oxynitride, light absorber, solar fuel, x-ray absorption spectroscopy, combinatorial materials science
Issue or Number:1
Record Number:CaltechAUTHORS:20171204-074721984
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Official Citation:Combinatorial Discovery of Lanthanum–Tantalum Oxynitride Solar Light Absorbers with Dilute Nitrogen for Solar Fuel Applications. Santosh K. Suram, Sean W. Fackler, Lan Zhou, Alpha T. N’Diaye, Walter S. Drisdell, Junko Yano, and John M. Gregoire. ACS Combinatorial Science 2018 20 (1), 26-34. DOI: 10.1021/acscombsci.7b00143
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83651
Deposited By: Tony Diaz
Deposited On:13 Dec 2017 05:16
Last Modified:15 Nov 2021 20:12

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