Understanding the correlation between the electronic structure and catalytic behavior of TiC(001) and TiN(001) surfaces: DFT study

Spin-unrestricted density functional theory (DFT) calculations are performed to explore the electronic structure and water-gas shift (WGS) behavior for the non-polar (001) surface of both titanium carbide (TiC) and titanium nitride (TiN). Previous researches have suggested that the unique electronic structures of these materials can effectively explain their surface adsorption and reactivity. Herein, our DFT calculations demonstrate that TiC(001) surface with occupied nonmetal C-2p states strongly binds CO molecule to the carbon site, and subsequently mediates the WGS along an associative mechanism. In contrast, TiN(001) surface dominated by metal Ti-3d states prefers to adsorb CO molecule at the titanium site, and then mediates WGS reaction through a redox mechanism. This indicates that the surface behavior of TiC(001) and TiN(001) is strongly dependent on their own electronic structure as expected. Therefore, the present studies provide an interesting perspective to understand the correlation between the electronic structure and catalytic behavior of such materials.