Synergistic effect to enhance hydrogen generation of Fe ₂ O ₃ /Ce _{0. 8} Sm _{0 . 1} Gd _{0 . 1} O _{1 .9} in water‐gas shift with chemical looping

Fe2O3 is recognized as a promising oxygen carrier, but the susceptibility to sintering over the redox cycles limits its application. Although depositing Fe2O3 on CeO2 can simultaneously improve the activity and durability, the formation of CeFeO3 will decrease the oxygen capacity and thus the efficiency of chemical looping water-gas shift reaction. Doping foreign elements can effectively mitigate the reaction between Fe2O3 and CeO2 and improve redox reactivity. This work employs Gd3+ and Sm3+ as doping elements and investigates the doping effect on hydrogen generation of Fe2O3/CeO2 in water-gas shift with chemical looping. The characterizations demonstrate that both Gd and Sm are incorporated into the lattice of CeO2 and increase the oxygen defect concentration, which boosts the redox reactivities. In addition, the interaction between the dopants and CeO2 promotes the reduction depth by suppressing the solid reaction between Fe2O3 and CeO2 and improves the reoxidation reaction between reduced oxygen carriers with steam. As a result, Fe2O3/Ce0.8Sm0.1Gd0.1O1.9 shows a high hydrogen yield (8.73 mmol.g−1) and hydrogen production rate (582.2 μmol.g−1.min−1), which is 1.67 times higher than that of Fe2O3/CeO2. The performance remains stable over 40 cycles. The introduction of foreign cations may provide an effective method and significantly impact the oxygen carrier design.