Continuous Low-Temperature Photothermal CO2 Desorption Enables Scalable Solar-Driven Direct Air Capture

Direct air capture (DAC) is increasingly recognized as an indispensable negative-emission technology for achieving carbon neutrality. However, its practical deployment is severely constrained by energy-intensive CO 2 desorption, high desorption temperature, poor stability, and complex batch operations. Here, we present a continuous low-temperature photothermal CO 2 desorption strategy that enables scalable solar-driven DAC. Photothermal polyethyleneimine–polyethylene glycol (PEI–PEG) functionalized pellets suitable for scalable applications are developed, which simultaneously demonstrate high broadband solar absorptance of 87.4%, good CO 2 adsorption capacity of 1.2 mmol·g −1 , and ultralow desorption temperature of 66 °C. The underlying mechanism is attributed to hydrogen bond cross-linking network of PEI and PEG, stabilizing the anime active sites and reducing the steric hindrance for internal CO 2 diffusion. Building on these materials, a kilogram-scale continuous photothermal CO 2 desorption system is established for the first time via integrating PEI–PEG adsorbent pellets with hourglass inspired self-rolling reactors. Remarkable solar-chemical efficiency of 24.8%, in stark contrast to only 11.5% for discontinuous batch reactor system, is demonstrated due to high pellet solar absorptance, low desorption temperature, and dynamic balance between pellets flow and incident photoenergy. This work establishes a promising pathway toward scalable, efficient, and low-carbon-footprint DAC through continuous low-temperature photothermal CO 2 desorption.