Design and synthesis of thermally stable single atom catalysts for thermochemical CO2 reduction

Abstract

The continuous and excessive emission of CO2 into the atmosphere presents a pressing challenge for global sustainable development. In response, researchers have been devoting significant efforts to develop methods for converting CO2 into valuable chemicals and fuels. These conversions have the potential to establish a closed artificial carbon cycle and provide an alternative resource to depleting fossil fuels. Among the various conversion routes, thermochemical CO2 reduction stands out as a promising candidate for industrialization. Within the realm of heterogeneous catalysis, single atom catalysts (SACs) have garnered significant attention. The utilization of SACs offers tremendous potential for enhancing catalytic performance. To achieve optimal activity and selectivity of SACs in CO2 thermochemical reduction reactions, a comprehensive understanding of key factors such as single atom metal-support interactions, chemical coordination, and accessibility of active sites is crucial. Despite extensive research in this field, the atomic-scale reaction mechanisms in different chemical environments remain largely unexplored. While SACs have been found successful applications in electrochemical and photochemical CO2 reduction reactions, their implementation in thermochemical CO2 reduction encounters challenges due to the sintering and/or agglomeration effects that occur at elevated temperatures. In this review, we present a unique approach that combines theoretical understanding with experimental strategies to guide researchers in the design of controlled and thermally stable SACs. By elucidating the underlying principles, we aim to enable the creation of SACs that exhibit stable and efficient catalytic activity for thermochemical CO2 reduction reactions. Subsequently, we provide a comprehensive overview of recent literature on noble metal- and transition metal-based SACs for thermochemical CO2 reduction. The current review is focused on certain CO2-derived products involving one step reduction only for simplicity and for better understanding the SACs enhancement mechanism. We emphasize various synthesis methods employed and highlight the catalytic activity of these SACs. Finally, we delve into the perspectives and challenges associated with SACs in the context of thermochemical CO2 reduction reactions, providing valuable insights for future research endeavor. Through this review, we aim to contribute to the advancement of SACs in the field of thermochemical CO2 reduction, shedding light on their potential as effective catalysts and addressing the challenges that need to be overcome for their successful implementation as paradigm shift in catalysis.