Nanoporous carbon nitride with a high content of inbuilt N site for the CO₂ capture

We report the nanoconfinement-mediated graphitic nanoporous carbon nitride (gNPCN) adsorbents with a high content of inbuilt basic nitrogen (N) (48%) by X-ray photoelectron spectroscopy (XPS) for efficient CO₂ adsorption. The gNPCNs (gNPCN-150 and gNPCN-130) are synthesized using the mesoporous SBA-15 silica template and a single carbon-nitrogen (C-N) precursor (guanidine hydrochloride). The various adsorbents were utilized for investigating the influence of pore size (PS), surface area (SA), and type of adsorbent for CO₂ adsorption performance. The capacity for CO₂ capturing of gNPCN-150 reached 23.1 mmol/g at 0 °C under 30 bar pressure. This CO₂ capturing capacity value was higher than the capacity gNPCN-130, SBA15, activated carbon (AC), and multiwalled carbon nanotube (MWCN) under identical conditions. The gNPCN materials exhibited superior CO₂ adsorption ability that is ascribed to the presence of the highly organized mesoporosity, inbuilt high content of basic N site for adsorbing more CO₂ through acid-base interaction, and tunable surface-structural properties. Moreover, the synthesis strategy is remarkably flexible in selecting C-N sources. This study features graphitic high-ordered nanoporous CN materials as a resourceful platform towards the efficient CO₂ capture.