Interfacial engineering strategies and sustainability assessment for direct electrolysis of dilute CO2 streams

The continuous decreasing in the levelized cost of renewable electricity has promoted the accelerated development of electrocatalysis, particularly electrochemical CO2 reduction (CO2R) using dilute CO2 concentrations (5-15%), which offers a sustainable pathway to convert waste CO2 into fuels and chemicals. However, dilute CO2 introduces substantial concentration overpotentials, leading to unsatisfactory selectivity and energy efficiency. Here, we develop effective approaches (pH control, amine addition, gas compression) to enrich the interfacial CO2 availability, steering the CO2R selectivity towards the desired products. We further conduct techno-economic analysis and cradle-to-gate life cycle assessments to evaluate their economic and environmental performance. For instance, HCOOH production cost drops from 1.11 to 0.47 $ kg-1, lower than the 0.58 $ kg-1 of the pure CO2 scenario. Moreover, environmental burdens such as climate change and cumulative energy demand decrease by 38.2%-72.0% relative to the flue-gas scenario without these strategies. Overall, although variations in the electricity mix influence the absolute values reported in this study, our work provides critical implications and design principles for dilute CO2R. Direct electrochemical upgrading of dilute CO2 from flue gas is attractive but limited by poor local CO2 availability and selectivity. Here, the authors report interfacial engineering strategies to enrich local CO2 and improve selectivity, supported by technoeconomic and life-cycle assessments.