Nitrogen Embedding Enhances Stability and Activity of Single-Atom Motifs of MXenes under Anodic Polarization

MXenes undergo water-mediated surface reconstruction under anodic polarization and spontaneously form single-atom centers, which are reminiscent of single-atom catalysts (SAC) and exhibit great potential for the oxygen evolution reaction (OER). Yet, the as-formed SAC-type MXene motifs still suffer from the conventional activity-stability trade-off under OER conditions. In this work, we propose a nitrogen embedding strategy to modulate the local coordination environment of the single-atom centers, thereby enhancing both their stability under anodic polarization and OER activity. Based on density functional theory calculations, we systematically evaluate 53 N-doped SAC-type MXene motifs, covering M ₂ X ₁ O, M ₃ X ₂ O, and M ₄ X ₃ O MXenes, using a three-step screening approach. This allows us to identify promising material candidates that i ) allow nitrogen doping under anodic polarization, ii ) are thermodynamically stable under OER conditions, and iii ) exhibit high OER activity. We demonstrate that N-doped Ta ₂ C ₁ O and N-doped Ta ₂ N ₁ O SAC-like MXenes break the traditional activity-stability trade-off in OER and provide theoretical guidance for the design of efficient and durable SAC-like MXene electrocatalysts.