Preparation of Amino‐Functionalized N‐Doped Graphene Adsorbent and Kinetic Study on Its Direct Air Capture of CO 2

This study introduces an N‐doped graphene‐based CO 2 adsorbent with hierarchical porosity and amine functionalization, specifically designed for direct air capture (DAC) of CO 2 in confined environments. The adsorbent was synthesized through hydrothermal self‐assembly, heteroatom doping, and tetraethylenepentamine impregnation. It exhibits a graphene‐like lamellar structure with interconnected pores (pore volume: 0.702 cm 3 /g, specific surface area: 127 m 2 /g) and demonstrates thermal stability up to 503 K. Under simulated confined conditions (323 K, 0.1 vol% CO 2 ), the adsorbent achieves an impressive adsorption uptake of 2.307 mmol/g and exhibits robust cyclic stability with less than 3% capacity loss over 10 cycles. Adsorption kinetics reveal a dual mechanism involving homogeneous site occupation and surface growth processes. Breakthrough curve analysis further identifies dynamic active site deactivation as the driving force behind the dimensional evolution of reaction pathways. Temperature‐programmed desorption confirms 383 K as the optimal regeneration temperature, enabling complete CO 2 release within 5 min. The derived kinetic parameters provide essential insights for the design of DAC of CO 2 .