TiC supported single-atom platinum catalyst for CO oxidation: A density functional theory study

The CO oxidation reaction over single-atom Pt catalyst dispersed on the defective TiC (1 0 0) surface with a Ti vacancy is studied using the dispersion-corrected density functional theory (DFT-D) computations. The stable configuration of the TiC supported single Pt atoms and the preferable CO oxidation reaction mechanisms are explored. The results demonstrate that the Pt atom may be tightly embedded in the surface Ti defect sites with a formation energy of -4.86 eV, forming a TiC supported single-atom platinum catalyst, marked as Pt@d-TiC. The adsorption characteristics of various adsorbates on Pt@d-TiC are investigated, and the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms for CO oxidation on Pt@d-TiC are simulated. Specifically, it is found that all the reaction species prefer to be adsorbed on the TiC support, indicating that the support vigorously participates in the catalytic reactions. In addition, the catalytic CO oxidation reaction over Pt@d-TiC favors to start with the L-H reaction. The rate-limiting step is the formation of the peroxide-like (OCOO) intermediate complex by the coadsorbed CO and O-2 with an activation barrier of 0.91 eV. The subsequent E-R reaction has a lower energy barrier of 0.45 eV. This work clearly shows the catalytic activity of the single-atom Pt supported on TiC for CO oxidation and perhaps for other reactions. (C) 2018 Elsevier B.V. All rights reserved.