Development and characterization of perovskite type oxide materials for hydrogen production

In this study, LaAlO3 family perovskite structure was chosen to observe the effect of A-site and B-site atoms whereas Na+ and Sr2+ as A-site atoms and Mg2+ and Mn3+ elements as B-site atoms, respectively. La1-xNaxAl1-yMyO3 (x=0,2, 0,4, 0,6, and 0,8; y=0,3, 0,5, 0,7, 0,9; M=Mg and Mn) ve La1-xSrxAl1-yMyO3 (x=0,2, 0,4, 0,6, and 0,8; y=0,3, 0,5, 0,7, 0,9; M=Mg and Mn compositions were investigated as redox materials in order to evaluate the effects of these compounds on oxygen production, hydrogen production, re-oxidation efficiency and structural stability that can be used in thermochemical water splitting cycles. Perovskite oxide materials synthesized by the Pechini method were subjected to heat treatment at 1300°C for 6 hours in order to obtain the targeted crystal structure. Structural analyzes of the synthesized powders were examined in detail, and SEM studies were carried out for morphological observation. After the structural analysis, it was observed that all compositions were synthesized with a perovskite structure, except for the La1-xSrxAl1-yMgyO3 perovskite family. Following this process, La1-xNaxAl1-yMnyO3, La1-xNaxAl1-yMgyO3 and La1-xSrxAl1-yMnyO3 perovskite oxide families were subjected to thermochemical redox reactions (Tred≈1400℃, Toks≈800℃) in order to evaluate their hydrogen production capacity. While H2 production was observed in all the compositions discussed, H2 production differed according to the additive elements and amounts in the compositions, as expected. The highest H2 production was obtained in the composition La0.4Sr0.6Al0.5Mn0.5O3 with a value of 254 µmol/g, this composition was followed by La0.6Sr0.4Al0.7Mn0.3O3 and La0.8Sr0.2Al0.9Mn0.1O3 compositions with a hydrogen production of 218 µmol/g and 164 µmol/g, respectively.