Mechanically Robust Silane-Engineered Aerogels for High-Affinity CO₂ Chemisorption under Low-Pressure, High-Temperature Conditions

Developing solid sorbents that combine mechanical durability with strong CO ₂ affinity under low-pressure, high-temperature conditions remains a central challenge. Here, we report silane-engineered silica–polymer hybrid aerogels in which (3-aminopropyl)triethoxysilane (APTES) and vinyltriethoxysilane (TEVS) construct a cross-linked organosiloxane network on a reinforced silica aerogel (SiA). This molecular restructuring greatly enhances structural stability, increasing the compressive strength from 2.14 MPa to 5.32 MPa (+ 148.6%) while preserving high porosity. Following the incorporation of polyethyleneimine, zinc acetate, and an imidazolium ionic liquid ([EMIm]Br) named PZI, the optimized materials exhibit substantially improved CO ₂ capture. Compared with SiA–PZI (2.24 mmol g⁻ ¹ at 298 K, 1 bar), optimized SiA–APTES–PZI reaches 2.95 mmol g⁻ ¹ (+ 31.7%), and achieves 2.05 mmol g⁻ ¹ at 50 mbar, evidencing a pronounced enhancement in low-pressure affinity. Moreover, it maintains 1.61 mmol g⁻ ¹ at 343 K and 30 mbar, underscoring its resilience under industrially relevant conditions. Furthermore, Toth-model fitting and Qst–uptake correlations reveal a distinct adsorption bifurcation: SiA–APTES–PZI features a broad spectrum of high-energy chemisorption sites originating from amine-rich domains and polar Zn ²⁺ /ionic-liquid co-domains, whereas SiA–TEVS–PZI operates mainly through micropore-dominated physisorption reinforced by CO ₂ –CO ₂ cooperative interactions. Together, these insights establish a generalizable design pathway for structurally reinforced, thermodynamically optimized CO ₂ sorbents for next-generation capture technologies.