The effect of hydrogen addition on the N2 formation from armchair carbonaceous surface

Abstract This work reveals the role of hydrogen in the N2 desorption using DFT calculations at the B3LYP/6-31G(d) level of theory as implemented in Gaussian 16 programme. The addition of one hydrogen on the active site, exothermicity by ≈380 kJ/mol, favors the hydrogenation of nearby active sites (ΔE ≈ 480 kJ/mol) but inhibits the hydrogenation of itself (ΔE ≈ 220 kJ/mol). N1 exposure with the highest barrier of 232.0 kJ/mol is the rate-determining step. By paying attention to this step, the potential roles are clarified: (1) two hydrogen attached to the same site creating a highly hydrogenated environment retards the overall reaction; (2) the attachment of one hydrogen to C2 site inhibits the overall reaction; and (3) the addition of one hydrogen on C1 and C3 sites favors the overall reaction. The proposed mechanism will help to explain various reported findings on the gasification of the carbonaceous surface.