Details

Autor(en) / Beteiligte

• Cavallaro, Andrea
• Wilson, George E
• Kerherve, Gwilherm
• Cali, Eleonora
• van den Bosch, Celeste A. M
• Boldrin, Paul
• Payne, David
• Skinner, Stephen J
• Aguadero, Ainara

Titel

Analysis of HO-induced surface degradation in SrCoO-derivatives and its impact on redox kinetics

Ist Teil von

• Journal of materials chemistry. A, Materials for energy and sustainability, 2021-11, Vol.9 (43), p.24528-24538

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Substituted SrCoO 3 perovskites have been proposed as promising mixed ionic electronic conductors for a range of applications including intermediate temperature solid oxide fuel cells (IT-SOFCs), electrolysers and thermochemical water splitting reactors for H 2 production. In this work we investigate the effect of sample exposure to water in substituted SrCoO 3 powders and thin films and correlate it with the degradation of oxygen mobility and kinetics. SrCo 0.95 Sb 0.05 O 3− δ (SCS) thin films have been deposited on different single crystal substrates by pulsed laser deposition (PLD). After water cleaning and post annealing at 300 °C, the sample surface presented an increase of the SrO-surface species as observed by ex situ X-ray Photoemission Spectroscopy (XPS) analysis. This increase in SrO at the sample surface has also been confirmed by the Low Energy Ion Scattering (LEIS) technique on both SCS thin film and powder. Thermochemical water splitting experiments on SCS and SrCo 0.95 Mo 0.05 O 3− δ (SCM) powder revealed a phase degradation under water oxidising conditions at high temperature with the formation of the trigonal phase Sr 6 Co 5 O 15 . Transmission Electron Microscopy (TEM) analysis of SCS powder treated with water suggests that this phase degradation could already superficially start at Room Temperature (RT). By isotope exchange depth profile experiments on SCS thin films, we were able to quantify the oxygen diffusivity in this SCS surface decomposed layer ( D * = 5.1 × 10 −17 cm 2 s −1 at 400 °C). In the specific case of bulk powder, the effect of water superficial decomposition translates into a lower oxidation and reduction kinetics as demonstrated by comparative thermogravimetric analysis (TGA) studies. Substituted SrCoO 3 surface decomposition in contact with water and its effect on the cathode redox kinetics.