Fig. 4. DFT calculation results of the chemical reaction pathway for CO oxidation.

Energy profiles for (A) the interfacial Pt-NiO_1−x and (B) the fully oxidized NiO on the stoichiometric Pt₃Ni structure. The optimized minimum and transition state (TS) structures are shown, and their relative energies are summarized by the solid black and red lines, respectively. For the energy barrier (E_TS) of the rate-determining step, the results for Pt(111) are also shown (blue) for comparison. The adsorbed species are denoted with asterisks (*). The colors for each atom in the model: Pt (light gray), Ni (green), O (red), and C (brown).