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

Abstract

Chemical looping H2O 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 H2 production rate and stability due to insufficient activation for H2O. Herein, it was found that the introduction of Cr into MgFe spinel oxides (MgFexCr2-xO4, MFCO) could greatly increase the performance of H2O splitting driven by CH4 reduction with the highest peak H2 production rate of about 4.65 mmol min−1 g−1, H2 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 Fe0 nanoparticles exsolution by activating CH4 and Fe-Ov-Cr species formation which relay catalyzed H2O splitting and was favorable for the fast recovery of lattice oxygen converted.