Electrochemical direct air capture by local alkalinity generation at three-dimensional interfaces.

Electrochemical direct air capture (eDAC) is a promising strategy for carbon dioxide (CO2) removal, offering advantages in energy efficiency, modularity, and potential for distributed deployment. However, existing systems are limited by low capture rates, energy-intensive regeneration, and challenges in stability and scalability. Here, we present a robust eDAC platform that addresses these limitations through key architectural innovations. The system generates hydroxides locally at the air-electrode interface to improve absorption kinetics and alkalinity utilization compared to conventional bulk solvent approaches. CO2 is subsequently released via a proton-coupled electron transfer mediator, enabling low-energy regeneration and high-purity gas output. Importantly, a porous interposer extends the reactive interface three-dimensionally to enhance CO2 capture efficiency. With an optimized interposer design and a pulsed current protocol, the system achieves stable operation for over 50 hours at current densities an order of magnitude higher than those of previous eDAC demonstrations, while maintaining competitive energy consumption. Multiphysics modeling and techno-economic analysis further guide system optimization and outline a viable path toward cost-effective scalability.