Theoretical and experimental study of the interaction of CO on TiC surfaces: Regular versus low coordinated sites

The adsorption of CO at regular and defect sites of the TiC surface has been studied by means of density functional theory (DFT) based calculations and temperature programmed desorption experiments (TPD) using TiC nanopowders as substrate whose structure and morphology have been characterized by X-ray diffraction and both scanning and transmission electron microscopy. The results obtained confirm previous work indicating that the nature of CO adsorption is strongly dependent on surface coverage due to the distortion of the surface induced by the adsorbate and also allows one to resolve an apparent anomaly between theory and experiment. Calculations and TPD experiments show that CO adsorption strength at regular sites is rather large with an adsorption energy of about − 1.60 eV which is consistent with a main desorption peak at ~ 500 K. Adsorption at low coordinated sites is even stronger and in agreement with desorption experiments indicating that CO continues to desorb at temperatures as high as 600 K.