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Novel perovskite materials for thermal water splitting at moderate temperature

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Azcondo, M. Teresa and Orfila, María and Marugán, Javier and Sanz Martín, Raúl and Muñoz Noval, Álvaro and Salas Colera, Eduardo and Ritter, Clemens and García Alvarado, Flaviano and Amador, Ulises (2019) Novel perovskite materials for thermal water splitting at moderate temperature. Chemsuschem . ISSN 1864-5631

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Official URL: http://dx.doi.org/10.1002/cssc.201901484




Abstract

Materials with the formula Sr_2CoNb_1-xTi_xO_(6-delta) (x=1.00, 0.70; delta=number of oxygen vacancies) present a cubic perovskite-like structure. They are easily and reversibly reduced in N_2 or Ar and re-oxidized in air upon heating. Oxidation by water (wet N_2), involving splitting of water at a temperature as low as 700 ºC, produces hydrogen. Both compounds displayed outstanding H_2 production in the first thermochemical cycle, the Sr_2CoNb_(0.30)Ti_(0.70)O_(6-delta) material retaining its outstanding performance upon cycling, whereas the hydrogen yield of the x=1 oxide showed a continuous decay. The retention of the materials' ability to promote water splitting correlated with their structural, chemical, and redox reversibility upon cycling. On reduction/oxidation, Co ions reversibly changed their oxidation state to compensate the release/recovery of oxygen in both compounds. However, in Sr_2CoTiO_(6-delta), two phases with different oxygen contents segregated, whereas in Sr_2CoNb_(0.30)Ti_(0.70)O_(6-delta) this effect was not evident. Therefore, this latter material displayed a hydrogen production as high as 410 mu molH_2/g_(perovskite) after eight thermochemical cycles at 700 ºC, which is among the highest ever reported, making this perovskite a promising candidate for thermosolar water splitting in real devices.


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©2019 Wiley-V C H VERLAG GMBH
We thank Agencia Estatal de Investigacion(AEI)/Fondo Europeo de Desarrollo Regional (FEDER/UE) for funding the project MAT2016-78632-C4-1-R. We acknowledge CSIC, ILL, and ESRF for financial support and facilitated access to the BM25-SpLine line at ESRF and D2B diffractometer at ILL. The authors also thank "Comunidad de Madrid" and the European Structural Funds for their financial support to the ALCCONES (S2013/MAE-2985) and MATERYENER3-CM (S2013/MIT-2753) projects.

Uncontrolled Keywords:Ray-absorption spectroscopy; Solar thermochemical h-2; Equal-to 0.5; Hydrogen-production; Redox-pair; Oxides; Stability; Cathode; Cycles; Edge; Hydrogen generation; Perovskite phases; Solar fuel; Thermochemical cycle; Water splitting
Subjects:Sciences > Physics > Materials
Sciences > Physics > Solid state physics
ID Code:57286
Deposited On:18 Oct 2019 15:16
Last Modified:21 Oct 2019 07:50

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