The possible reaction mechanisms for CO catalytic oxidation by O 2 molecule on the Pd-doped hexagonal boron nitride nano- sheet (Pd-BNNS) were studied using first-principles calculations. The large adsorption energy of the Pd atom over the boron- vacancy defect of BN nanosheet suggests that Pd-BNNS could be stable under high temperatures. According to our results, the adsorption of CO over Pd-BNNS is energetically preferable than that of O 2 . Three different reaction pathways of the CO oxidation are investigated comparably: the Eley-Rideal (ER), the Langmuir-Hinshelwood (LH) and the termolecular Eley-Rideal (TER). Our results indicate that the CO oxidation reaction would like to take place via the TER mechanism due to its small activation energies. The calculated energy barrier for the rate- determining step of the latter pathway is only 0.19 eV. Based on electronic structure analysis, such high catalytic activity of Pd-BNNS can be related to the strong hybridization of the Pd- 4d and CO-5σ/CO-2π* states, which effectively activates the adsorbed CO molecules involved in the TER mechanism.
