First-principles study of an efficient non-noble metal single-atom catalyst Fe₁/TiVCO₂ for CO oxidation

MXenes, a class of two-dimensional layered materials of transition metal carbides, nitrides, and carbonitrides, have piqued the interest of researchers due to their unique physical and chemical properties. The crystal structure, electronic structure, stability, and catalytic activity of a new MXene-based single-atom catalyst (SAC) Fe-1/TiVCO2 have been studied by first principles, showing that this SAC exhibits excellent catalytic activity for CO oxidation. Research has shown that charge transfer from Fe-1/TiVCO2 to adsorbed CO and O-2 molecules plays an important role in molecular activation. The CO oxidation mechanisms of Langmuir-Hinshelwood (LH), Eley-Rideal (ER), and termolecular Eley-Rideal (TER) were explored. All three reaction mechanisms are feasible at low temperatures, and the activation barrier energies for rate-limiting steps are 0.72 eV, 1.00 eV, and 0.40 eV, respectively. The results indicate that Fe-1/TiVCO2 exhibits the highest activity for CO oxidation through the TER mechanism.