Review and Outlook of Lattice Oxygen Migration in Oxygen Carrier during Chemical Looping Processes

Chemical looping (CL) technology is believed a promising technology for fuel conversion with inherent CO2 capture, oxygen carrier is one of the key factors that affect the reaction rate, conversion, and selectivity. Fuel is generally oxidized by the lattice oxygen in oxygen carriers, and understanding the migration of lattice oxygen is of great importance in developing oxygen carriers. This study systematically reviews recent advances in lattice oxygen migration, which includes multiscale study methods, descriptions of migration pathway, method to enhance oxygen migration, etc., with an emphasis on their effects on redox kinetics and structural stability. First, the structure–property-performance relationships across representative oxygen carrier systems were examined, single metal oxides, spinel, perovskites, and fluorite-type materials were specifically analyzed. Second, recent advances for methods of tuning lattice oxygen migration, such as elemental doping and structural design, are discussed in detail. In addition, advances in experimental and theoretical tools, including density functional theory (DFT), reactive force field molecular dynamics (ReaxFF-MD), in situ spectroscopy, and isotope labeling, are highlighted for their ability to enable multiscale analysis of oxygen migration behavior. Last, based on above review, directions in development of high-performance oxygen carriers is suggested, and composite structures to enhance oxygen migration capabilities would mainly focused the integration of advanced experimental and computational frameworks is urgently needed to accurately unveil the intrinsic mechanisms of lattice oxygen migration.