Highly sintering-resistant iron oxide with a hetero-oxide shell for chemical looping water splitting

Abstract

Chemical looping water splitting is a promising technology that couples carbonaceous fuel oxidation to produce H2 with inherent CO2 separation. Redox catalyst with long-term performance is the key issue but is hampered in traditional Fe2O3-based approaches due to Fe sintering. This study reports a one-step sol-gel synthetic method to construct Fe2O3@Hetero-oxide redox catalysts with core-shell structure, leading to outstanding anti-sintering property in TGA analysis (>250 cycles, 5000 min). Fixed-bed reactor tests showed that hydrogen yield approached theoretical value (16.7 mmol/g-Fe2O3), with ∼100 % H2 purity. This result is significantly better than dispersing a mixed ionic-electronic conductor (MIEC) in Fe2O3 matrix using high energy ball milling. Although the latter can enhance the durability due to facilitated O2− and electron transportation, Fe sintering and redox catalysts deactivation is inevitable. This study offers a generalized structure design and synthetic approach for anti-sintering redox catalysts within chemical looping concepts.