Effect of Synthesis on Quality, Electronic Properties and Environmental Stability of Individual Monolayer Ti₃C₂ MXene Flakes

Abstract

Abstract2D transition metal carbide Ti 3 C 2 T x (T stands for surface termination), the most widely studied MXene, has shown outstanding electrochemical properties and promise for a number of bulk applications. However, electronic properties of individual MXene flakes, which are important for understanding the potential of these materials, remain largely unexplored. Herein, a modified synthetic method is reported for producing high-quality monolayer Ti 3 C 2 T x flakes. Field-effect transistors (FETs) based on monolayer Ti 3 C 2 T x flakes are fabricated and their electronic properties are measured. Individual Ti 3 C 2 T x flakes exhibit a high conductivity of 4600 ± 1100 S cm −1 and fieldeffect electron mobility of 2.6 ± 0.7 cm 2 V −1 s −1 . The resistivity of multilayer Ti 3 C 2 T x films is only one order of magnitude higher than the resistivity of individual flakes, which indicates a surprisingly good electron transport through the surface terminations of different flakes, unlike in many other 2D materials. Finally, the fabricated FETs are used to investigate the environmental stability and kinetics of oxidation of Ti 3 C 2 T x flakes in humid air. The high-quality Ti 3 C 2 T x flakes are reasonably stable and remain highly conductive even after their exposure to air for more than 24 h. It is demonstrated that after the initial exponential decay the conductivity of Ti 3 C 2 T x flakes linearly decreases with time, which is consistent with their edge oxidation. A l h a b e b , e t a l . i n A d v a n c e d E l e c t r o n i c M a t e r i a l s 2 ( 2 0 1 6 digitalcommons.unl.edu L i p a t o v &

Electrophoretic Deposition of Two-Dimensional Titanium Carbide (MXene) Thick Films

“…Films made by EPD at 5 V from aqueous suspensions had an electrical resistivity of 135 ± 10 μ -cm (or a conductivity of 7400 S/cm), whereas those made by EPD from PC suspensions at 5 V and 25 V had resistivities of 128 ± 23 μ -cm and 176 ± 19 μ -cm, respectively. These resistivities are among the lowest reported for Ti 3 C 2 T x and slightly lower than those reported for highly-oriented spin-coated films, 30 epitaxial thin films, 13 single-flake, 51 and other types of Ti 3 C 2 T x films, 52 as summarized in Table II. This proves that EPD is a high-throughput and efficient method to make highly conductive Ti 3 C 2 T x films.…”

2D titanium carbide (MXene) for wireless communication

“…Lipatov et al . ( 28 ) showed that, although Ti 3 C 2 single-layer flake’s conductivity decays in air, Ti 3 C 2 remains highly conductive even after exposure to air for 70 hours. Stacks of single-layer Ti 3 C 2 flakes, such as filtered or sprayed MXene films, are stable in air.…”

Electrochromic Effect in Titanium Carbide MXene Thin Films Produced by Dip‐Coating

“…[1,2] These technologies require materials that are visibly transparent, yet electrically conductive. [21,22] Ti 3 C 2 T x shows high metallic conductivity (8-10 kS cm −1 ), [23] hydrophilicity, sufficient chemical and environmental stability, [24,25] and promise as a transparent conductor due to the absorption of only ≈3% of visible light per nanometer thickness. [3] This material property, electrochromism, is associated with change in the oxidation state or ion insertion and extraction upon reduction and oxidation of the active general formula of M n+1 X n T x , where M is an early transition metal, X is C and/or N, and T x represents surfaces termination such as O, OH, and/or F. [19,20] Titanium carbide (Ti 3 C 2 T x ) was the first discovered and is the most studied MXene [17] and it can be synthesized at a large scale with high quality.…”