Azcondo, M. TeresaOrfila, MaríaMarugán, JavierSanz Martín, RaúlMuñoz Noval, ÁlvaroSalas Colera, EduardoRitter, ClemensGarcía Alvarado, FlavianoAmador, Ulises2023-06-172023-06-172019-07-081864-563110.1002/cssc.201901484https://hdl.handle.net/20.500.14352/13665©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.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.engjournal articlehttp://dx.doi.org/10.1002/cssc.201901484https://onlinelibrary.wiley.comopen access538.9Ray-absorption spectroscopySolar thermochemical h-2Equal-to 0.5Hydrogen-productionRedox-pairOxidesStabilityCathodeCyclesEdgeHydrogen generationPerovskite phasesSolar fuelThermochemical cycleWater splittingFísica de materialesFísica del estado sólido2211 Física del Estado Sólido