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

Abstract

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 Ti 2 C (Ti 2 CO 2 ) supported single-atom catalysts M 1 /Ti 2 CO 2 (M = Fe, Co, Ni, Cu Ru, Rh, Pd, Ag Os, Ir, Pt, Au). A new non-noble metal SAC Fe 1 /Ti 2 CO 2 has been found to show excellent catalytic performance for low-temperature CO oxidation after screening the group 8-11 transition metals. We find that O 2 and CO adsorption on Fe 1 atom of Fe 1 /Ti 2 CO 2 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, Fe 1 /Ti 2 CO 2 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 Fe 1 /Ti 2 CO 2 MXene is highly promising 2D materials for building robust non-noble metal catalysts. MXene supported non-noble metal single-atom catalyst Fe 1 /Ti 2 CO 2 is found to exhibit excellent activity for low-temperature CO oxidation through first-principles computational modelling.