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 operando 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.