Enhanced hydrogen production of Fe-based spinel by relay catalysis of Fe0 and Fe-Ov-Cr species in chemical looping H2O splitting

Chemical looping H 2 O splitting is considered as a promising approach to produce hydrogen thanks to its lower energy consumption and carbon footprint compared with traditional steam reforming. Fe-based oxides have been paid much attention but suffer from inferior H 2 production rate and stability due to insufficient activation for H 2 O. Herein, it was found that the introduction of Cr into MgFe spinel oxides (MgFe x Cr 2-x O 4 , MFCO) could greatly increase the performance of H 2 O splitting driven by CH 4 reduction with the highest peak H 2 production rate of about 4.65 mmol min −1 g −1 , H 2 productivity of about 2.88 mmol g −1 and good stability during multiple redox cycles for MFCO-46 (the atomic ratio of Fe and Cr of 2:3), which exceeded most of the state-of-the-art Fe-based oxides. This originated from the Cr doping promoting Fe 0 nanoparticles exsolution by activating CH 4 and Fe-O v -Cr species formation which relay catalyzed H 2 O splitting and was favorable for the fast recovery of lattice oxygen converted.