Nano Express (Jan 2024)
Synthesis, physico-chemical characterization, DFT simulation, and field electron behaviour of 2D layered Ti3C2Tx MXene nanosheets
Abstract
Nanostructures of Ti _3 C _2 T _x , one of the members of the MXenes family, have been successfully prepared by chemical etching of Al from Ti _3 AlC _2 ( MAX phase) using Hydrofluoric Acid (HF) for various etching durations at room temperature. The phase, morphological, structural, and chemical analysis was performed using XRD, FESEM, TEM, Raman, and x-ray photoelectron spectroscopy. The surface morphology of as-synthesized Ti _3 C _2 T _x ( MXene) phase is characterized by stacks of layered sheets like structures. Field electron emission (FEE) behaviour was investigated at the base pressure of 1 × 10 ^−8 mbar. The pristine Ti _3 AlC _2 ( MAX ) and Ti _3 C _2 T _x ( MXene ) nanosheets emitters showed values of turn-on field (defined at current density ∼ 1 μ A cm ^−2 ) as 4.18 and 1.67 V μ m ^−1 , respectively. Furthermore, maximum emission current density of ∼ 825 μ A cm ^−2 was extracted from the MXene nanosheets emitter at an applied field of 3.60 V μ m ^−1 , in contrast to ∼71 μ A cm ^−2 drawn at 7.31 V μ m ^−1 from the pristine MAX emitter. The MXene nanosheets emitter exhibited good emission current stabilities at pre-set values ∼ 10 and 100 μ A over 3 h duration. Work function values of the MAX and MXene nanosheets emitters were measured using a retarding field analyzer, and found to be 4.4 and 3.6 eV, respectively. Extensive ab-initio simulations have been performed to provide structural and electronic properties, as well as for estimating the work function of Ti _3 C _2 layered material. The estimated electronic density of states revealed its metallic character. The improved FEE performance exhibited by the 2D layered Ti _3 C _2 T _x ( MXene ) nanosheets emitter is attributed to its unique morphology characterized by high aspect ratio, metallic electronic properties and relatively lower work function.
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