Reversible Adsorption and Light-Driven Release of CO₂ Using Hollow Carbon Sphere-Based Adsorbents with Photothermal Conversion Feature

CO2 capture and storage (CCS), an important negative CO2 emissions technology, offers a promising solution for alleviating the greenhouse effect and achieving the carbon neutrality target set by the Paris Climate Accord. However, current strategies using amine-based adsorbents suffer from the issues of energy-intensive adsorbent regeneration and the heating requirement to release CO2 for storage and utilization. Here, we report a novel photothermal adsorbent, hollow carbon spheres encapsulating poly(ethylenimine) (PEI@HCS), which features efficient CO2 capture and photocontrolled desorption capabilities. Upon light irradiation, the surface temperature of PEI@HCS rises to approximately 120 °C due to the photothermal properties of HCS, enabling the release of 0.96 mmol-CO2 g-adsorbent–1 (91% of the captured CO2). In contrast, the traditional SiO2-supported PEI adsorbent (PEI/SiO2) achieves only 65 °C with no CO2 desorption. PEI@HCS also exhibits excellent reusability over multiple dark–light cycles, which is associated with the protective effect of HCS. Furthermore, a correlation study reveals that both mesoporous pore volume and specific surface area show a positive correlation with CO2 adsorption performance, which can be modulated by varying the PEI content and the calcination temperature of HCS preparation. This work is anticipated to offer new inspiration for the development of green and energy-saving carbon capture and storage technologies.