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Atomic Defects in Monolayer Titanium Carbide (Ti 3 C 2 T x ) MXene

2016; American Chemical Society; Volume: 10; Issue: 10 Linguagem: Inglês

10.1021/acsnano.6b05240

1936-086X

Xiahan Sang, Yu Xie, Ming‐Wei Lin, Mohamed Alhabeb, Katherine L. Van Aken, Yury Gogotsi, Paul R. C. Kent, Kai Xiao, Raymond R. Unocic,

Ferroelectric and Negative Capacitance Devices

The 2D transition metal carbides or nitrides, or MXenes, are emerging as a group of materials showing great promise in lithium ion batteries and supercapacitors. Until now, characterization and properties of single-layer MXenes have been scarcely reported. Here, using scanning transmission electron microscopy, we determined the atomic structure of freestanding monolayer Ti3C2Tx flakes prepared via the minimally intensive layer delamination method and characterized different point defects that are prevalent in the monolayer flakes. We determine that the Ti vacancy concentration can be controlled by the etchant concentration during preparation. Density function theory-based calculations confirm the defect structures and predict that the defects can influence the surface morphology and termination groups, but do not strongly influence the metallic conductivity. Using devices fabricated from single- and few-layer Ti3C2Tx MXene flakes, the effect of the number of layers in the flake on conductivity has been demonstrated.