Step-change in high temperature steam electrolysis performance of perovskite oxide cathodes with exsolution of B-site dopants

George Tsekouras, Dragos Neagu, John T.S. Irvine

Research output: Contribution to journalArticlepeer-review

157 Citations (Scopus)

Abstract

B-site doped, A-site deficient perovskite oxide titanates with formula La0.4Sr0.4Mn+xTi1-xO 3-γ-δ (M = Fe3+ or Ni2+; x = 0.06; γ = (4 - n)x/2) were employed as solid oxide electrolysis cell (SOEC) cathodes for hydrogen production via high temperature steam electrolysis at 900 °C. A-site deficiency provided additional driving force for the exsolution of a proportion of B-site dopants at the surface in the form of metallic nanoparticles under reducing SOEC cathode operating conditions. In the case of La0.4Sr0.4Fe0.06Ti0.94O 2.97, this represents the first time that Fe0 has been exsolved from a perovskite in such a way. Exsolution was due in part to the inability of the host lattice to accommodate vacancies (introduced (δ) oxygen vacancies () and fixed A-site () and inherent (γ) oxygen vacancies) beyond a certain limit. The presence of electrocatalytically active Fe 0 or Ni0 nanoparticles and higher concentrations dramatically lowered the activation barrier to steam electrolysis compared to the parent material (x = 0). The use of defect chemistry to drive the exsolution of less reducible dopant cations could conceivably be extended to produce new catalytically active perovskites with unique properties.

Original languageEnglish
Pages (from-to)256-266
Number of pages11
JournalEnergy and Environmental Science
Volume6
Issue number1
DOIs
Publication statusPublished - 22 Nov 2012
Externally publishedYes

Keywords

  • step-change
  • steam electrolysis
  • perovskite cathode

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