Solid phosphate buffers boost CO2 capture performance and enable energy-lean operation in amine-functionalized adsorbents

Abstract Amine-functionalized solid adsorbents represent promising next-generation materials for efficient CO2 capture. However, their practical deployment is constrained by a fundamental trilemma balancing CO2 adsorption capacity, adsorption kinetics and regeneration energy efficiency. Herein, we resolve this challenge through catalytic proton shuttle engineering by incorporating sodium dihydrogen phosphate into tetraethylenepentamine-functionalized mesoporous silica gel (HP-TEPA/MSG). The phosphate modifier exhibits dual functionality which not only enhances TEPA dispersion within mesopores to improve mass transfer efficiency, but also establishes atomic-scale proton transfer networks through buffer microdomains that accelerate proton shuttling during adsorption-desorption cycles. Compared to unmodified TEPA/MSG, the optimized 3HP-TEPA/MSG adsorbent achieves 18.7% higher CO2 capacity, 28% faster adsorption kinetics (the time required to reach 90% of the saturated adsorption capacity) and 27% lower regeneration energy. This work resolves the persistent capacity-kinetics-energy trilemma through proton-coupled reaction engineering, establishing a new paradigm for designing energy-lean carbon capture materials.