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Co-design of zinc titanium nitride semiconductor towards durable photoelectrochemical applications

Greenaway, Ann L. and Ke, Sijia and Culman, Theodore and Talley, Kevin R. and Mangum, John S. and Heinselman, Karen N. and Kingsbury, Ryan S. and Smaha, Rebecca W. and Miller, Elisa M. and Persson, Kristin A. and Gregoire, John M. and Bauers, Sage R. and Neaton, Jeffrey B. and Tamboli, Adele C. and Zakutayev, Andriy (2022) Co-design of zinc titanium nitride semiconductor towards durable photoelectrochemical applications. . (Unpublished)

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Photoelectrochemical fuel generation is a promising route to sustainable liquid fuels produced from water and captured carbon dioxide with sunlight as the energy input. Development of such technologies requires photoelectrode materials that are both photocatalytically active and operationally stable in harsh oxidative and/or reductive electrochemical environments. Such photocatalysts can be discovered based on co-design principles, wherein design for stability is based on the propensity for the photocatalyst to self-passivate under operating conditions and design for photoactivity is based on the ability to integrate the photocatalyst with established semiconductor substrates. Here we report on synthesis and characterization of zinc titanium nitride (ZnTiN2) that follows these design rules by having a wurtzite-derived crystal structure and showing self-passivating surface oxides created by electrochemical polarization. The sputtered ZnTiN₂ thin films have optical absorption onsets below 2 eV and n-type electrical conduction of 0.1 S/cm. The band gap of this material is reduced from the 3.5 eV theoretical value by cation site disorder, and the impact of cation antisites on the band structure of ZnTiN₂ is explored using density functional theory. Under electrochemical polarization, the ZnTiN₂ surfaces have TiO₂- or ZnO-like character, consistent with Materials Project Pourbaix calculations predicting the formation of stable solid phases under near-neutral pH. These results show that ZnTiN₂ is a promising candidate for photoelectrochemical liquid fuel generation and demonstrate a new materials design approach to other photoelectrodes with self-passivating native operational surface chemistry.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Greenaway, Ann L.0000-0001-6681-9965
Miller, Elisa M.0000-0002-7648-5433
Persson, Kristin A.0000-0003-2495-5509
Gregoire, John M.0000-0002-2863-5265
Neaton, Jeffrey B.0000-0001-7585-6135
Zakutayev, Andriy0000-0002-3054-5525
Additional Information:The content is available under CC BY NC ND 4.0 License. This work was performed in part at the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. This material is primarily based upon work performed by the Liquid Sunlight Alliance, a DOE Energy Innovation Hub, supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC0021266. T.C. acknowledges support from DOE Office of Science, Office of Workforce Development for Teachers and Scientists under the Science Undergraduate Laboratory Internship program (optical and electrical characterization). R.W.S. acknowledges support from the Director’s Fellowship within NREL’s Laboratory Directed Research and Development program (oriented material growth). The development and analysis of the hybrid Pourbaix diagrams was supported by the Materials Project, which is funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract no. DE-AC02-05-CH11231: Materials Project program KC23MP. Maintenance and development of the NRELMatDB is currently supported by the US Department of Energy, Office of Science, Basic Energy Sciences under contract DE-AC36-08GO28308 to NREL, as part of an Energy Frontier Research Center. The authors acknowledge the support of Dennice Roberts in the preparation of this manuscript. The views expressed in this article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes. This project was jointly conceived of by A.L.G., K.R.T., S.R.B., A.C.T., and A.Z. with J.M.G.’s input. A.Z., K.R.T., R.W.S, and J.S.M. synthesized the ZnTiN2 films and characterized them by XRD and XRF. J.S.M. performed SEM imaging. S.K. and J.B.N. carried out theoretical electronic structure calculations. T.C. and S.R.B. conducted optical and electrical property measurements. K.N.H. and S.R.B. collected and analyzed RBS data, respectively. A.L.G. and K.N.H. designed and performed electrochemical experiments. R.S.K. and K.A.P. modeled ZnTiN2 electrochemical stability. E.M.M. performed XPS measurements and analysis. A.C.T. and A.Z. were responsible for funding acquisition and project management; K.A.P., J.M.G., and J.B.N. were also responsible for funding acquisition. A.L.G., S.R.B., S.K., J.S.M., J.M.G., and A.Z. contributed to writing the manuscript and designing the figures, and all other authors provided feedback. The author(s) have declared they have no conflict of interest with regard to this content. The author(s) have declared ethics committee/IRB approval is not relevant to this content.
Group:Liquid Sunlight Alliance
Funding AgencyGrant Number
Department of Energy (DOE)DE-AC36-08GO28308
Department of Energy (DOE)DE-SC0021266
National Renewable Energy LaboratoryUNSPECIFIED
Department of Energy (DOE)DE-AC02-05-CH11231
Subject Keywords:photoelectrochemistry; thin film; nitride; carbon dioxide reduction reaction; Pourbaix; DFT
Record Number:CaltechAUTHORS:20220414-25692000
Persistent URL:
Official Citation:Greenaway AL, Ke S, Culman T, et al. Co-design of zinc titanium nitride semiconductor towards durable photoelectrochemical applications. ChemRxiv. 2022. doi:10.26434/chemrxiv-2022-chbvt-v2
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114293
Deposited By: George Porter
Deposited On:19 Apr 2022 20:35
Last Modified:19 Apr 2022 20:35

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