Computational investigation on CO2 capturing capacity of N-doped and Na-decorated Graphdiyne

Abstract

Graphdiyne (GDY) is a newly discovered member of the two-dimensional carbon allotropes that has been proposed as a material for carbon dioxide (CO2) capture and storage technology. The GDY structure is composed of several hybridized carbon atoms, and despite its superior electronic capabilities, modifying its structure can facilitate the advancement of its practical applications. This study considered, N-doping, Na-decoration, and their combinations as GDY modifications. The dispersion-corrected density functional theory (DFT-D2) approach was used to investigate the structural and electronic properties of the resultant adsorbents and their CO2 adsorption behavior. Among three different N-doped structures, substituting an N atom for the Carbon with hybridization of SP2-SP (CSP2-SP) produced the most stable N-doped GDY with Ecoh = −7.23 eV. Four different locations of GDY were decorated by Na atom, and the center of the H3 was identified as the most stable site with Eads = −3.804 eV. This site was also the most favorable for Na decorating of the N-doped GDY, with Eads = −3.347 eV. Moreover, the results indicated that when a single CO2 was adsorbed on the Na-decorated GDY, the adsorption energy was −0.432 eV, the highest value among the pristine and modified structures. However, evaluation of the maximum CO2 capturing capacity of the systems revealed that N-doped GDY could capture eleven CO2 molecules, ca. 68.92 wt%, which makes it a potential candidate for future CO2 capture, storage, detection, and removal applications.