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

Abstract 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 M₂X₁O, M₃X₂O, and M₄X₃O 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 Ta₂C₁O and N-doped Ta₂N₁O 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.