Novel Perovskite Materials for Thermal Water Splitting at Moderate Temperature Articles uri icon

authors

  • AZCONDO, M. TERESA
  • ORFILA, MARIA
  • MARUGAN, JAVIER
  • SANZ, RAUL
  • MUÑOZ NOVAL, ALVARO
  • SALAS COLERA, EDUARDO
  • RITTER, CLEMENS
  • GARCIA ALVARADO, FLAVIANO
  • AMADOR, ULISES

publication date

  • July 2019

start page

  • 4029

end page

  • 4037

issue

  • 17

volume

  • 12

International Standard Serial Number (ISSN)

  • 1864-5631

Electronic International Standard Serial Number (EISSN)

  • 1864-564X

abstract

  • Materials with the formula Sr2CoNb1−xTixO6−delta (x=1.00, 0.70; delta=number of oxygen vacancies) present a cubic perovskite‐like structure. They are easily and reversibly reduced in N2 or Ar and re‐oxidized in air upon heating. Oxidation by water (wet N2), involving splitting of water at a temperature as low as 700 °C, produces hydrogen. Both compounds displayed outstanding H2 production in the first thermochemical cycle, the Sr2CoNb0.30Ti0.70O6−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 Sr2CoTiO6−delta, two phases with different oxygen contents segregated, whereas in Sr2CoNb0.30Ti0.70O6−delta this effect was not evident. Therefore, this latter material displayed a hydrogen production as high as 410 mumol H2 g−1perovskite after eight thermochemical cycles at 700 °C, which is among the highest ever reported, making this perovskite a promising candidate for thermosolar water splitting in real devices.

keywords

  • hydrogen generation; perovskite phases; solar fuel; thermochemical cycle; water splitting