Single Pt atom supported on penta-graphene as an efficient catalyst for CO oxidation

Single-atom catalysts (SACs) have gained special attention due to their unique performances in CO oxidation. Herein, a single Pt atom supported on penta-graphene (Pt/PG) was explored as a SAC towards CO oxidation by applying spin-polarized first-principles calculations. The possible mechanisms for CO oxidation by O-2 on Pt/PG, including two traditional mechanisms, Eley-Rideal (ER) and Langmuir-Hinshelwood (LH), and a new tri-molecular Eley-Rideal (TER) mechanism, are illustrated. Our computations revealed that the direct ER pathway (O-2 + CO -> O + CO2) and TER pathway (2CO + O-2 -> OCO-OCO -> 2CO(2)) with activation energies of 0.11-0.20 eV and 0.35 eV for the rate-limiting step, respectively, were more preferable than the LH pathway (0.45 eV). The TER pathway was proposed as the most favored pathway since the adsorption of CO was much stronger than the adsorption of O-2, allowing for the ER pathway to be restrained. This finding demonstrated that Pt/PG as a single-atom catalyst exhibited an excellent catalytic activity toward CO oxidation and provided a new strategy for the design of single-atom catalysts based on penta-graphene.