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.
