Density functional theory study of CO2 capture and storage promotion using manipulation of graphyne by 3d and 4d transition metals

In this work, the electronic and structural properties of 3d and 4d transition metal (TM)-decorated graphyne (GY) (TM-GY) toward CO₂ adsorption were studied using the D3-corrected density functional theory (DFT-D3) method. Then, CO₂ capture and storage (CCS) of the most stable structures were investigated. Results show that the most stable site for all TM decoration is the center of the 12-membered ring with various distances from carbon plane, and GY decorated with Ni and Zn from 3d and Zr and Cd from 4d TMs are also the most and the least stable, energetically with E_b of −5.834, −0.467, −6.181, and −0.963 eV, respectively. Evaluation of the adsorption behavior of CO₂ on TM-GY reveals that the strongest adsorption energies belong to Cr and Mo-GY (−1.502 and −1.117 eV, respectively), and for all 3d and 4d TMs, the horizontal direction of CO₂ is more stable, energetically. Increasing CO₂ molecules, step by step, on Cr and Mo-GY shows that they can hold 13 and 18 CO₂ molecules with average E_ads of −0.374 and −0.330 eV/CO₂ and corresponding CO₂ storage capacities of 47.66 and 54.10 wt%, respectively. These findings show that Cr and Mo-GY can be used in the future as suitable candidates for CCS applications.