Nitrogen- and sulfur-doped triphenylbenzene-based hyper cross-linked polymers for high-performance CO₂ adsorption

The increasing concentration of atmospheric CO₂ has stimulated the development of efficient and sustainable adsorbents for carbon capture. Hypercrosslinked polymers (HCPs), a subclass of porous organic polymers (POPs), are attractive candidates owing to their permanent porosity, high stability, and simple, cost-effective synthesis. Herein, two N- and S-containing triphenylbenzene-based HCPs, namely TPB-Cz HCP and TPB-Tz HCP, were constructed using AlCl₃-catalyzed Friedel–Crafts reaction. Their structures and physicochemical properties were systematically characterized by FT-IR, solid-state NMR, XRD, SEM, TEM, XPS, TGA, and N₂ adsorption–desorption analyses. TPB-Cz HCP exhibited a high BET surface area of 1077 m² g⁻¹ and a total pore volume of 0.65 cm³ g⁻¹. It also demonstrated superior CO₂ adsorption capacities of 3.50 mmol g⁻¹ at 273 K and 2.32 mmol g⁻¹ at 298 K (1 bar), together with a CO₂/N₂ selectivity of 18.54 and an isosteric heat of adsorption of 26.24 kJ mol⁻¹. DFT calculations revealed stronger framework–CO₂ interactions in TPB-Cz HCP, consistent with the experimental adsorption results. Furthermore, dynamic breakthrough experiments and repeated adsorption–desorption cycles confirmed its excellent separation performance, regeneration ability, and moisture tolerance. These results highlight the synergistic effects of accessible microporosity and framework chemistry that govern the CO₂ capture efficiency of TPB-based HCPs, providing valuable design principles for advanced carbon capture materials.