Reactivity enhancement via cobalt doped La–Sr–Mn perovskite oxygen carriers for chemical looping hydrogen generation

Chemical looping hydrogen generation (CLHG) is a novel technology to produce pure hydrogen without high energy consumption. The reactivity of oxygen carriers determines the CLHG performance. In this work, cobalt substitution is adopted to enhance the reactivity of La 0.8 Sr 0.2 MnO 3 oxygen carriers. Redox test and characterization results suggest that cobalt doping facilitated release of lattice oxygen, causing more oxygen vacancies in the perovskites during reduction stage. In the water-splitting stage, oxygen vacancies provided active sites for steam splitting, enhancing the reactivity of oxygen carriers and improving the generation rate and yield of hydrogen. On the other hand, higher Co-substitution proportion (x ≥ 0.5) can lead to carbon deposition in the reduction stage and then destroy hydrogen purity in the water-splitting stage. La 0.8 Sr 0.2 Mn 0.7 Co 0.3 O 3 oxygen carrier exhibits relatively superior CLHG performance with pure hydrogen yield of 3.20 mmol g −1 . This work provides a significant guidance of performance improvement for water-splitting hydrogen production.