Investigating the potential of X-doped (X = Mg, Rh, N, P, S) monolayer MoSe2 as effective adsorbents for I2 and CH3I in nuclear energy applications

Abstract

This study meticulously delved into the electronic and structural properties of monolayer MoSe₂, as well as the adsorption capacity of I₂ and CH₃I, using first-principles and the density functional theory. Five promising dopants (Mg, Rh, N, P, and S) were employed to enhance the adsorption characteristics of MoSe₂. The study examined in detail the improved interaction mechanism of MoSe₂ with I₂ and CH₃I after the doped process. The results of the study revealed that the MoSe₂ monolayer exhibited chemisorption for I₂ and a weak physical adsorption capacity for the CH₃I molecules. The adsorption energy of the I₂ molecule improved substantially within the five doped MoSe₂ systems. The P- and Mg-doped systems achieved dissociation of I₂ molecules, with the I-I bond lengths increasing from their initial value of 2.682 Å to 3.276 Å and 3.248 Å, respectively. The maximum absolute adsorption value of the P-MoSe₂-I₂ system was found to be 2.004 eV, which was much higher compared to the 0.652 eV that was obtained for the pure system. The C-I bond lengths of the CH₃I molecules for the Mg- and Rh-doped systems increased from the initial value of 2.150 Å to 4.382 Å and 3.269 Å, respectively. As a result, these molecules were dissociated into their constituent methyl and iodine atoms. The adsorption energy of the Mg-MoSe₂-CH₃I system reached a maximum absolute value of 2.454 eV, which was 2.108 eV higher in comparison with that of the pure system. The Bader charge analysis showed that the charge transfer of I₂ and CH₃I adsorbed by the Mg-doped system had the highest value, equal to 1.057 and 1.390 e, respectively. The density of states results after the adsorption of I₂ and CH₃I by P- and Mg-doped systems revealed significant hybridization of the P 3p orbitals with the I 5p orbitals and of the Mg 3 s orbitals with the I 5p and the C 2p orbitals. Also, chemisorption of I₂ and CH₃I was achieved. The findings confirmed that modified MoSe₂ has enormous potential as an adsorbent material for removing I₂ and CH₃I in nuclear energy applications.