Atomic oxygen adsorption on the silicon-doped hafnium carbide (0 0 1) surface from first principles

To improve the oxidation resistance of Hafnium carbide (HfC) surface, we investigated the adsorption of atomic oxygen on the silicon–doped HfC (0 0 1) surface by first principles. The O/HfC (0 0 1) system was also calculated for comparison. The (√2 × √2) R45° supercell was constructed to calculate the adsorption. In calculations, we treated the exchange and correlation potential with the revised version of the Perdew–Burke–Ernzerhof generalized-gradient approximation (GGA-RPBE). Our data demonstrate that the preference adsorption site for oxygen atom is the 4–fold hollow site on the silicon–doped HfC (0 0 1) surface. The oxygen on the silicon–doped surface receives more charges from silicon atoms than that in O/HfC (0 0 1) from carbon atoms. The Si–O bonds exhibit ionic and covalent characteristics, while the C–O bond exhibits primarily covalence. And the covalence of Si–Hf bonds is stronger than that of C–Hf bonds. The strong Si–O and Si–Hf bonds indicate the strong interactions of oxygen with the silicon–doped surface. The strong interactions can explain the possibility of improving the oxidation resistance of HfC surface via doping silicon.

► We substitute silicon atoms for the carbon atoms on the outermost atomic plane of the HfC (0 0 1) surface. ► The preference adsorption site for oxygen atom is the 4-fold hollow site on the silicon–doped HfC (0 0 1) surface. ► The interaction of oxygen with the silicon–doped HfC (0 0 1) surface is stronger than that with the HfC (0 0 1) surface. ► The strong Si–O and Si–Hf bonds suggest a low tendency for the silicon–doped HfC (0 0 1) surface to oxidize.