Photo switching porous materials for CO2 capture and utilization

Abstract

Climate change, widely recognized as the most pressing global health threat of the 21st century, demands effective counter strategies. Central to these efforts is Carbon Capture and Utilization (CCU). Traditional CO2 liberation technologies, primarily pressure and vacuum-based, are energy-intensive.


However, innovations have revealed that light-based methods can offer a more efficient alternative, especially if the adsorbents exhibit potent light absorption alongside CO2 adsorption. This thesis focuses on the potential of Photo-switching porous materials which, due to their capacity for low-energy CO2 capture and release using light control, have attracted considerable attention. Notably, the introduction of azobenzene into porous materials has led to notable achievements. These azobenzene units, besides enhancing CO2 adsorption, also impart photo-switching capabilities to the materials. It's shown that after exposure to UV light, these materials experience reduced CO2 adsorption, which can be reversed using thermal heating. This process, illustrating the CO2 capture and release cycle, is proven stable across multiple cycles.Key findings include the significant role of azobenzene units in enhancing the CO2 uptake capacities of these materials. Additionally, by modulating the structural properties of these units, an improvement in the switching efficiency of these materials is observed. Beyond their role in CO2 capture, azobenzene-based porous materials have also shown potential in the photocatalytic CO2 reduction process, particularly when paired with palladium, leading to high CO2 to CH4 conversion efficiency.

The materials presented in this thesis not only demonstrate reduced energy costs and consumption in CO2 capture compared to conventional methods, but they also showcase superior chemical and thermal resilience. This resilience, combined with their efficiency, positions them as promising candidates for a range of applications, including potential integration into membranes for capturing CO2 from power plant emissions, offering an environmentally-friendly and economical solution.

Thesis is embargoed until 31 December 2026.

Date of Award	Dec 2023
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Chinese Scholarship Council (CSC)
Supervisor	Chunfei Wu (Supervisor), Peter Robertson (Supervisor) & Bo Xiao (Supervisor)