Advancing CO₂ Valorization Beyond C₂ Products.

Abstract

The catalytic valorization of carbon dioxide (CO₂) has attracted extensive attention as a promising route to mitigate greenhouse gas emissions while producing value-added chemicals. Significant progress has been achieved in the selective reduction of CO₂ to C₁ and C₂ products such as CO, CH₄, HCOO^-, C₂H₄, and C₂H₅OH through precise control of catalysts and reaction environments within single-batch systems. However, the formation of higher-order carbon products (C₃+) remains a major challenge because it requires complex multielectron and multiproton transfer steps, typically involving 18-20 electrons and protons for intermediates such as propanol or propylene. These demanding reaction pathways lead to sluggish C-C-C coupling kinetics and limited energy utilization under conventional single-cell configurations. Recent advances have focused on multibatch cascade catalytic systems that integrate thermochemical, photochemical, and electrochemical processes to overcome these intrinsic barriers. By enabling the stepwise conversion of CO₂-derived intermediates, such hybrid platforms improve selectivity and efficiency toward C₃+ products that are difficult to achieve in single-batch systems. Nevertheless, the integration of distinct reaction environments introduces challenges, including intermediate loss between reactors and reduced overall energy efficiency. This review provides a comprehensive overview of cascade strategies for CO₂ conversion, emphasizing mechanistic understanding, reactor design, and <i>operando</i> characterization. The discussion aims to guide the rational design of next-generation catalytic architectures capable of achieving efficient and scalable C₃+ production from CO₂ through improved control of multistep extended hybrid reaction pathways and interfacial energy management.