An ONIOM study of H₂O interacting with the C-terminated surface of silicon carbide

A combined first principle and molecular mechanics research on the adsorption and surface reactions of H₂O molecule with the C-terminated silicon carbide surface was carried out. The three-layered ONIOM(B3PW91/6-31g(d):AM1:UFF) approach on the (SiC)₁₉₂·H ₂O model was examined. Three distinct adsorption styles (molecular adsorption, molecular hydrogen dissociation adsorption and the H-OH bond dissociative adsorption) and eight possible reaction channels were found. The results show that there are three competitive reactions over the eight channels and the H₂O molecule is in favor of dissociating the H-OH bond by the absorptions on the adjacent surface atoms.