Improved Electrochemical Direct Air Capture by an Extended Absorption Layer

Electrochemical carbon capture based on an interfacial high-pH microenvironment represents a significant advancement in carbon capture technologies; however, its design remains constrained by limited carbon mass diffusion within the ultrathin catalyst layer, particularly in direct air capture (DAC) applications. Here, we demonstrated a practical approach to enhance interfacial CO2 mass transport through the implementation of an extended absorption layer (EAL) design. By incorporating the EAL into a porous solid electrolyte (PSE) reactor performing oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) redox electrolysis, we achieved a seven-fold increase in both electron efficiency (10 mA cm–2, 28%) and CO2 capture rate (0.7 × 10–3 mL s–1 cm–2) for the DAC process. Stable operation of more than 35 days and continuous production of near-saturated carbonated water solely from indoor air were demonstrated in our device, indicating its practical applicability.