Review on Migration and Transformation of Lattice Oxygen during Chemical Looping Conversion: Advances and Perspectives

Chemical looping technology is one of the most promising approaches in the fields of fuel conversion, pollution removal, energy conservation, and carbon dioxide capture and utilization and has been extensively investigated for more than two decades. A majority of the chemical looping process is achieved through the migration and transformation of lattice oxygen. Thus, exploring the migration and transformation of lattice oxygen is critical to clarify chemical looping's reaction rules to allow for further control of reaction selectivity and yield. Herein, recent advances in the exploration of lattice oxygen's migration mechanism are systematically reviewed, with a focus on structure–activity relationships. The great roles that characterization techniques perform to address the challenges in exploring the migration mechanism of lattice oxygen activities are discussed first. We then outline the categories of oxygen carrier materials and the migration mechanism of lattice oxygen. Lastly, the most promising research directions that design high-performance oxygen carriers with well-regulated lattice oxygen activity through the redox reaction mechanism are overviewed. We infer that the research on the relationship between lattice oxygen activity and target products is challenging but essential─it is a direction worthy of our efforts in the future.