Insights into the Redox Performance of Non–stoichiometric Lanthanum Manganite Perovskites for Solar Thermochemical CO2 Splitting

Abstract

AbstractPerovskite structured mixed metal oxides are one category of redox materials that recently demonstrated high potential for solar fuel production from thermochemical H2O/CO2 splitting. Substituted lanthanum manganite perovskite was previously found to be one of the most suitable candidates among the perovskite family, owing to its unique redox properties. However, the effect of synthesis method and cationic substitutions in A and B‐sites of ABO3 perovskite need to be elucidated. Herein, a systematic study was performed by implementing various synthetic strategies such as solid‐state, pechini process, glycine combustion or glucose‐assisted methods, to obtain LaxSr1‐xMnO3 (LSM) as a single phase and to determine the effect of synthesis method on the redox efficiency and performance stability for CO2 splitting. The results indicated that the materials synthesized by the pechini method were the most reactive among the series, with a stable CO production of ∼260 μmol.g−1 for x=0.5. Also, various pure phase A and B‐site substituted perovskites were synthesized by the pechini method to study the effect of such substitutions on the fuel yield of these materials. Y/Ca/Ba A‐site and Al/Fe B‐site substitutions in (La,Sr)MnO3 did not enhance the redox cycling capability when compared with LSM. It was observed that Sr was the best A‐site substituent and the presence of single Mn cation alone in B‐site was the most suitable option for promoting CO2‐splitting activity. Further, the effect of the addition of promotional agents was explored and enhancement of CO evolution was observed when compared to pure LSM.