Effect of oxygen termination on the interaction of first row transition metals with M2C MXenes and the feasibility of single-atom catalysts

A density functional theory-based study was performed to investigate the stability of single-atom catalysts (SACs) over a series of O-terminated MXenes with the stoichiometry of M2CO2. Accordingly, we selected the first-row transition metals as adatoms and nine MXene surfaces as supports. From a thermodynamic viewpoint, the stability of the resulting SACs is favorable for all combinations between adatoms and MXenes. However, the adatoms tend to cluster together to a rather low energy barrier, promoting diffusion, which significantly affects their stability. The present systematic study showed that Sc@ and Ti@M2CO2 are the most feasible SACs because of their high metal-support interaction, low tendency to form metal clusters and high diffusion barriers. The present results can be useful to experimentalists aimed at synthesizing SACs based on MXenes