DFT-D3 calculations of the charge-modulated CO2 capture of N/Sc-embedded graphyne: Compilation of some factors

The increasing greenhouse gases, including CO2 in the atmosphere, have a devastating effect on the ecosystem. Therefore, scientists are trying to provide new materials for CO2 capture, storage, and conversion. In this work, we consider CO2 capture behavior of N, Sc, and Sc/N embedded graphyne (GY) for neutral and negatively charge states by DFT-D3 calculations. It is found that in the most stable structures with single N (N1-GY) or Sc (Sc1-GY) and in Sc/N-GY, N and Sc atoms prefer to stand in the chains and the H1 sites of GY, respectively. E-ads values of CO2 onto pristine GY (PGY) and N1-GY in neutral or negatively charged states are low (physisorption) (-0.212 to -0.286 eV); while insertion of Sc causes that CO2 capture improves even in neutral state to -0.726 eV for Sc1-GY and promotes considerably in -2 e negatively charged Sc/N-GY1 up to -3.186 eV. It can say that synergistic effect of N and Sc insertion and -2 e negatively charged on the PGY causes a 1500% increasing of CO2 adsorption energy. Evaluation of the CO2 adsorption/desorption mechanism for negatively charged Sc1-GY and Sc/N-GY1 structures represents that choosing the proper charge state is very effective on the CO2 regeneration process.