Field Emission Performance of 2D Ti ₂ CT _<i>x</i> (T _<i>x</i> = O ₂ , F ₂ , O–F) MXene: Experimental Insights and Theoretical Endorsement

Field emission (FE) is an important electron emission mechanism for vacuum microelectronic devices; however, conventional emitters often exhibit high turn-on fields, limited emission stability, and degradation during prolonged operation. Two-dimensional MXenes have recently emerged as promising FE materials due to their remarkable electrical conductivity, comparatively low work function, and tunnelable surface terminations. Nevertheless, most studies have focused on Ti3C2Tx MXene, while other compositions such as Ti2CTx remain largely unexplored, particularly regarding the influence of surface terminal groups on their electronic and emission properties. Herein, Ti2CTx (Tx = −F2, −O2, −OF) MXene was synthesized via selective chemical etching of the Ti2AlC MAX phase and investigated for its FE characteristics. The material exhibits a polycrystalline hexagonal layered structure with a high specific surface area of 349.02 m2 g–1. Ti2CTx MXene demonstrates excellent FE performance with a low turn-on field of 1.56 V μm–1 and a threshold field of 2.0 V μm–1 (at 10 μA cm–2), along with a stable emission for 4 h. Density functional theory calculations further reveal that surface terminations strongly influence the electronic structure and work function, with the experimental value of 4.66 eV closely matching the −F2 termination. These results highlight Ti2CTx MXene as a promising material for stable and efficient FE applications.