Multiple and nonlocal cation redox in Ca-Ce-Ti-Mn oxide perovskites for solar thermochemical applications

Wexler, RB and Sai Gautam, G and Bell, RT and Shulda, S and Strange, NA and Trindell, JA and Sugar, JD and Nygren, E and Sainio, S and McDaniel, AH and Ginley, D and Carter, EA and Stechel, EB (2023) Multiple and nonlocal cation redox in Ca-Ce-Ti-Mn oxide perovskites for solar thermochemical applications. In: Energy and Environmental Science, 16 (6). pp. 2550-2560.

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Abstract

Modeling-driven design of redox-active off-stoichiometric oxides for solar thermochemical H2 production (STCH) seldom has resulted in empirical demonstration of competitive materials. We report the theoretical prediction and experimental evidence that the perovskite Ca2/3Ce1/3Ti1/3Mn2/3O3 is synthesizable with high phase purity, stable, and has desirable redox thermodynamics for STCH, with a predicted average neutral oxygen vacancy (VO) formation energy, Ev = 3.30 eV. Flow reactor experiments suggest potentially comparable or greater H2 production capacity than recent promising Sr-La-Mn-Al and Ba-Ce-Mn metal oxide perovskites. Utilizing quantum-based modeling of a solid solution on both A and B sub-lattices, we predict the impact of nearest-neighbor composition on Ev and determine that A-site Ce4+ reduction dominates the redox-activity of Ca2/3Ce1/3Ti1/3Mn2/3O3. X-ray absorption spectroscopy measurements provide evidence that supports these predictions and reversible Ce4+-to-Ce3+ reduction. Our models predict that Ce4+ reduces even when it is not nearest-neighbor to the VO, suggesting that refinement of Ce stoichiometry has the possibility of further enhancing performance.

Item Type:	Journal Article
Publication:	Energy and Environmental Science
Publisher:	Royal Society of Chemistry
Additional Information:	The copyright for this article belongs to the Royal Society of Chemistry
Keywords:	Aluminum alloys; Barium compounds; Cerium alloys; Cerium oxide; Forecasting; Lanthanum alloys; Manganese alloys; Redox reactions; Strontium alloys; Ternary alloys; Thermodynamics; X ray absorption spectroscopy, reductions; Experimental evidence; H 2 production; Mn oxides; Model driven design; Nearest-neighbour; Nonlocal; Oxide perovskite; Redox-active; Thermochemicals, Perovskite
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	25 Jul 2023 04:59
Last Modified:	25 Jul 2023 04:59
URI:	https://eprints.iisc.ac.in/id/eprint/82593

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