Identifying of Pure and Defected Ti C Materials Using Gas Probe Molecules: First Principles Calculations.

Employing first principles calculations, we systematically investigated the geometrical and electronic structures of pure, titanium defected (D ) and carbon defected (D ) Ti C materials. We found the defected Ti C exhibits stronger metallic property than pure Ti C due to the enhanced density of Ti-d orbital state near the Fermi level. We then studied the adsorption as well as the infrared spectrum (IR) response of the four kinds of gas molecules (CH , NH , CO and NO) on pure, D and D Ti C surfaces. Simulations show that CO and NO molecules are chemically adsorbed on all Ti C surface with similar adsorption sites. However, CH and NH molecules would be dissociated on Ti C surface. Negative values of crystal orbital Hamilton population as well as the PDOS calculations show that the red shift in IR spectra of CO and NO molecules originates from the decreasing bonding strength of probe molecules. The present work provides rich insight for the adsorption and identification for different Ti C materials.