(707d) Exsolution of Nife Nanoparticles on Ni-Doped (La,Sr)FeO3: Its Effect on Co-Electrolysis of CO2 and H2o for Syngas Production
AIChE Annual Meeting
Friday, November 18, 2022 - 1:24pm to 1:42pm
In this study, A-site deficient, strontium and nickel doped lanthanum ferrite perovskite oxide (LSNF) was synthesized as a SOEC cathode material. LSNF perovskite has demonstrated the exsolution of NiFe nanoparticles and structural transformation to Ruddlesden-Popper (RP) phase under a reducing environment at 500â800 oC, as determined by different methods of characterization such as TPR, ETEM and in-situ XRD. The XRD patterns showed that Red-LSNF was composed of hetero-phases including La2NiO4, La2O3 and the exsolved nanoparticles, which formed a uniform size distribution (4.2â9.2 nm) and dispersion (1.31â0.61x104 particle Î¼mâ2). Additionally, it has been found that the exsolution process is reversible in such a way that Red-LSNF is re-oxidized to its original perovskite structure under oxidizing environment. The redox ability of LSNF perovskite allows for re-establishing the nanoparticle distribution as is needed. The electrocatalytic activity results showed that Red-LSNF has significantly higher activity for the co-electrolysis of CO2 and H2O due to the presence of reduced oxidation states of B-site ions (proved by XPS and XANES results), better accessibility of the active sites via exsolution of active nanoparticles to the electrode surface, and formation of oxygen vacancies that serve as adsorption sites for CO2 and H2O. The reduction of LSNF ultimately improved the electrochemical performance by 66â73% on ASRs for H2O, CO2, and H2O/CO2 electrolysis at 800 oC.