Non-noble metal single-atom catalyst with MXene support: Fe1/Ti2CO2 for CO oxidation

MXenes have attracted considerable attention owing to their versatile and excellent physicochemical properties. Especially, they have potential applications as robust support for single atom catalysts. Here, quantum chemical studies with density functional theory are carried out to systematically investigate the geometries, stability, electronic properties of oxygen functionalized Ti2C (Ti2CO2) supported single-atom catalysts M1/Ti2CO2 (M = Fe, Co, Ni, Cu Ru, Rh, Pd, Ag Os, Ir, Pt, Au). A new non-noble metal SAC Fe1/Ti2CO2 has been found to show excellent catalytic performance for low-temperature CO oxidation after screening the group 8-11 transition metals. We find that O2 and CO adsorption on Fe1 atom of Fe1/Ti2CO2 is favorable. Accordingly, five possible mechanisms for CO oxidation on this catalyst are evaluated, including Eley-Rideal, Langmuir-Hinshelwood, Mars–van Krevelen, Termolecular Eley-Rideal, and Termolecular Langmuir-Hinshelwood (TLH) mechanisms. Based on the calculated reaction energies for different pathways, Fe1/Ti2CO2 shows excellent kinetics for CO oxidation via TLH mechanism, with distinct low-energy barrier (0.20 eV) for the rate-determining step. These results demonstrate that Fe1/Ti2CO2 MXene is highly promising 2D materials for building robust non-noble metal catalysts.