Delivering low-energy carbon capture with photo-responsive hypercrosslinked polymers derived from polystyrene waste

Abstract

Highly effective but energy-intensive techniques such as temperature and pressure swing adsorption are typically deployed to regenerate adsorbents used in carbon capture. Here we show that the energy consumption and costs associated with adsorbent regeneration can be reduced by 500-fold when photo-responsive hypercrosslinked polymers (HCPs) recycled from waste expanded polystyrene that are loaded with 8.9 wt% of azobenzene are deployed for carbon capture. Our approach uses UV light (365 nm) to enhance the adsorption of CO₂ from a variety of mixed gas concentrations with CO₂ content between 1–40 v/v%. 14% of CO₂ adsorbed on HCPs@Azo can be desorbed by irradiation with visible light. The photo-regeneration efficiency of adsorption and desorption capacities of HCPs@Azo stabilised at 50% after 5 cycles, demonstrating good reusability. The low energy footprints and synthesis and operating costs of our photo-responsive HCPs@Azo can potentially reduce carbon capture costs and establish a green carbon capture process driven by light.