The effect of electric field on hydrogen storage for B/N-codoped graphyne

Abstract

Hydrogen adsorption on a B/C/N sheet under different external electric fields is investigated by first-principles calculations. Through the analyses of structural properties of the B/C/N system, we find that N_bB_f, B_bN_o, B_aN_e, and N_aB_g are more probable to be synthesized. Through molecular dynamics calculations, it was found that the structures for B/N doped graphyne are stable. For N_bB_f, B_bN_o, B_aN_e, and N_aB_g, the most stable positions for hydrogen adsorption are the H1 sites. For a single H₂ adsorbed on a B/C/N sheet, the adsorption energy increases greatly as the electric field increases, and the maximum adsorption energy is 0.506 eV when the electric field is 0.035 a.u. It is also found that the adsorption energy of H₂ adsorbed on N_bB_f under electric field increases faster than H₂ adsorbed on other sheets. The interaction between H₂ molecule and B/C/N sheet is the Kubas interaction under an external electric field.