(569fw) Influence of SOx on Exsolution Mechanism for Formation of Nife Nanoparticle

Perovskite oxide materials constitute an emerging alternative to Ni/YSZ as thermochemical and electrochemical energy material due to their enhanced oxygen vacancy mobility and redox stability. Exsolution further enhances oxygen vacancy of perovskite oxide and additionally facilitates formation of exsolved nanoparticles, both contributing to catalytic activity of thermochemical water splitting. Anthropogenic SOx contaminant is known to cause oxidation of exsolved nanoparticles, and sulphidization, phase transformation and total destruction/breakdown of perovskite oxide materials. Here, the influence of SOx exposure on exsolution mechanism and formation of NiFe nanoparticle is assessed for LaFe_0.9Ni_0.1O₃ (LFNO) that has demonstrated exsolution and dissolution of NiFe in reductive and oxidative environment, respectively. SOx exposure of LFNO at 600 ^oC indicates the formation of sulfate and sulfite, yet, NiFe nanoparticles can still be exsolved, dissolved and re-exsolved with some compositional changes when compared with NiFe exsolved from as-prepared LFNO. Raman indicates faster segregation of Ni and formation of intermediate La₂FeO₄ Ruddlesden–Popper phase during exsolution. Water splitting activity of the reduced LFNO is enhanced at low temperature and sustained at higher temperature due to the exsolved NiFe nanoparticle. While Fe provides activity majorly at ~ 500 ^oC and gets easily oxidized at higher temperature, Ni activity begins at low to moderate temperature, which is sustained even at higher temperature. However, after SOx exposure of LFNO, there is a significant decrease in activities of both Ni and Fe from exsolved NiFe and Ni oxidation peak occurs at lower temperature, suggesting a significant interruption in the exsolution mechanism and formation of NiFe nanoparticle due to SOx exposure. Understanding the exsolution kinetics and sulphate behavior of SOx exposed LaFe_0.9Ni_0.1O₃ under exsolution will be critical towards regeneration of SOx-exposed perovskite oxide material for thermochemical water splitting.