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, reminiscent of single-atom catalysts (SAC), which 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. Here, 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, which identifies promising 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 Ta2N1O SAC-like MXenes break the traditional activity-stability trade-off in OER and provide theoretical guidance for designing efficient and durable SAC-like MXene electrocatalysts.