Earth abundant spinel for hydrogen production in a chemical looping scheme at 550 ℃

Operating chemical looping process at mid-temperatures (550-750℃) presents exciting potential for the stable production of hydrogen. However, the reactivity of oxygen carriers is compromised by the detrimental effect of the relatively low temperatures on the redox kinetics. Although the reactivity at mid-temperature can be improved by the addition of noble metals, the high cost of these noble metal containing materials significantly hindered their scalable applications. In the current work, we propose to incorporate earth-abundant metals into the iron-based spinel for hydrogen production in a chemical looping scheme at mid-temperatures. Mn_0.2Co_0.4Fe_2.4O₄ shows a high hydrogen production performance at the average rate of ∼0.62 mmol g^-1 min^-1 and a hydrogen yield of ∼9.29 mmol g^-1 with satisfactory stability over 20 cycles at 550℃. The mechanism studies manifest that the enhanced hydrogen production performance is a result of the improved oxygen-ion conductivity to enhance reduction reaction and high reactivity of reduced samples with steam. The performance of the oxygen carriers in this work is comparable to those noble-metal containing materials, enabling their potential for industrial applications.