A Redox-Switchable Framework Bridges Dilute-Stream CO2 Capture and Conversion

Abstract Integrating CO2 capture from dilute sources with electrochemical conversion could bypass the energy-intensive separation and regeneration required in conventional carbon capture and utilization. Yet combining these functions, particularly for multicarbon electrosynthesis, remains challenging. Here, we report an ion-regulated conjugated pyridine-imine framework (Cr-PyN) that performs both electrochemical CO2 capture and selective conversion to acetate within a single metal-free molecular platform through potential-dependent molecular reactivity. Reduction activates the pyridine-imine unit for CO2 binding, while Na+ coordination within the crown cavity regulates the interfacial environment and suppresses hydrogen evolution. Cr-PyN captures CO2 directly from simulated flue gas (9.3% CO2, 3% O2) with an electron utilization efficiency of 0.98 and a minimum electrical energy requirement of 39 kJ mol–1 CO2. At more cathodic potentials in an aqueous flow electrolyzer, the same molecular framework selectively produces acetate with 71% Faradaic efficiency at –0.4 V versus the reversible hydrogen electrode and remains stable over 120 h. Complementary in situ and ex situ spectroscopic studies, including operando FTIR and NMR, along with DFT calculations, support CO2 binding and subsequent reaction pathways toward multicarbon conversion.