Facile Fabrication and High Field Emission Performance of 2-D Ti₃C₂Tₓ MXene Nanosheets for Vacuum Electronic Devices

Although Ti
₃
C
₂
T
_x
has been widely studied in applications such as electrical storage devices, there are very few reports about the field emission properties of Ti
₃
C
₂
T
_x
. In this work, 2-D Ti
₃
C
₂
T
_x
MXene was fabricated by simple etching Al layer from Ti
₃
AlC
₂
in hydrofluoric acid (HF) at room temperature and employed as a cold cathode for field emission devices. The device presents a high field emission performance with a low turn-on field of 2.7 V/μm and excellent stability, much lower than the reported value of the former work (around 5 V/μm), its relative 1-D TiC nanowires (7.1 V/μm), and most of other 2-D cathode materials, such as MoS
₂
and graphene, which is found due to its unique accordion structure with evenly distributed sharp edges and enlarged layer spacing reducing the field screening effect. The results confirmed by numerical simulation demonstrate that the local electric intensity at sharp edges indeed significantly higher than that of elsewhere. In other words, more sharp edges owning to the increased interlayer spacing exposed, which can considerably boost field emission performance. Based on experimental data and simulation analysis, the edge effect was found to correspond well with other former reports. Hence, 2-D MXene can be a promising candidate for vacuum electronic applications other than energy storage and conversion devices.