Solar Thermochemical Redox Cycling Using Ga- and Al-Doped LSM Perovskites for Renewable Hydrogen Production
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- doe_osti · checked 2024-09-17
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Solar thermochemical hydrogen production using redox-active metal oxides is a promising pathway for the production of green hydrogen and synthetic fuel precursors. Herein, the perovskite material (La<sub>0.6</sub>Sr<sub>0.4</sub>)<sub>0.95</sub>Mn<sub>0.8</sub>Ga<sub>0.2</sub>O<sub>3–δ</sub> (LSMG6482) is identified as a promising metal oxide for thermochemical water splitting. LSMG6482, along with more-established water splitters ceria and (La<sub>0.6</sub>Sr<sub>0.4</sub>)<sub>0.95</sub>Mn<sub>x</sub>Al<sub>1–x</sub>O<sub>3–δ</sub> (LSMA) perovskites, is experimentally characterized via thermogravimetric (TGA) analysis and high-temperature water splitting in a reactor simulating solar concentrating conditions. TGA analysis demonstrated that LSMG6482 has high and stable oxygen exchange capacity under controlled pO<sub>2</sub> redox cycling, demonstrated by large changes in oxygen nonstoichiometry (δ) relative to ceria. Water splitting experiments using laser heating (T<sub>red</sub> = 1400 °C, T<sub>ox</sub> = 1200 °C) resulted in H<sub>2</sub> yields of 165.1 μmol g<sup>–1</sup> for the candidate LSMG6482 composition, exceeding that of all benchmark materials tested. Under high conversion oxidation conditions, where H<sub>2</sub> is cointroduced with H<sub>2</sub>O (150 ≤ nH<sub>2</sub>O/nH<sub>2</sub> ≤ 500), H<sub>2</sub> yields were greatest for LSMG6482 and LSMA6482, up to four times that of ceria at the highest nH<sub>2</sub>O/nH<sub>2</sub> conditions. Crystallographic analysis showed that over the course of experimentation, there is some secondary phase growth for all perovskite compositions, except for LSMA6482, but there was no observable degradation in H<sub>2</sub> yields.. Authors: McCord, Dylan C. [University of Florida, Gainesville, FL (United States); University of Florida] (ORCID:0000000260831354); Gager, Elizabeth J. [University of Florida, Gainesville, FL (United States)]; Wang, Ximeng [University of Florida, Gainesville, FL (United States)] (ORCID:0000000239437184); Johnson, Taylor L. [University of Florida, Gainesville, FL (United States)]; Beachy, Jonas S. [University of Florida, Gainesville, FL (United States)]. DOE Contract: EE0008840; NA0003525. Subjects: 08 HYDROGEN; 14 SOLAR ENERGY; Materials; Oxidation; Oxides; Perovskites; Redox reactions