The aim of the project is to carry out basic research on the preparation and structural characterization of two-dimensional hexagonal titanium carbides, called MXenes (Ti3C2Tx), by the deposition of the MAX phases (Ti3AlC2) onto Al2O3(0001) substrate, graphene and carbon nanotubes, followed by the removal of A layer from the synthesized system.
Transition metal carbides and carbonitrides (MXenes) are new, uncharted 2D nanomaterials family discovered in 2011. The MXene (Mn+1XnTx) abbreviation is related to etched MAX phases (Mn+1AXn) and graphene structure.
MAX phases are prepared in the form of powdered ceramic sinter or thin layers of nanolaminates with the following composition: M - early transition metal, A - mainly a group IIIA or IVA element and X - carbon and / or nitrogen. Stoichiometric composition of the MAX phases depends on "n" multiplier which allow to obtain 211 (n=1), 312 (n=2) and 413 (n=3) structures. MAX phases are layered hexagonal crystals with space group P63/mmc, where the M layers are nearly closed packed, and the X atoms fill the octahedral sites.
In MAX phases, the strong M-X bond has a mixed covalent/metallic/ionic character, whereas the M-A bond is metallic. Thanks to their structure, MAX phases possess unique combination of properties typical for both metals and ceramics, such as high thermal and electrical conductivity, low density, high resistance to mechanical damage, oxidation and corrosion.
In case of Ti3AlC2, the Al etching via wet chemistry methods leads to formation of quasi 2D multilayered Ti3C2Tx accordion like structures (where Tx are functional groups: -F, =O, -OH). Intercalation of multilaered MXenes and further delamination by ultrasound treatment allow to obtain single or few layered hexagonal Ti3C2Tx structure - morphologically similar to graphene flakes.
Currently, scientific facilities around the world are investigating the potential application of MXene structures in nanocomposites, filtration, flexible nanoelectronics, sensing and energy storage systems (lithium-ion batteries, supercapacitors).
As part of the project, the research is conducted in two ways: (i) on the synthesis of the MAX phases thin films via deposition of electron beam vapor deposition (EB-PVD) layers and their etching to obtain the MXenes structures and (ii) on the production of MAX phase powders by volume combustion synthesis and subsequent etching of multi-layered MXenes structures.
The most essential challenge in the project is to produce thin phases of MAX phases and MXenes structures on carbon nanomaterials, that require parameterization of the mono- or polycrystalline MAX phases deposition onto classic sapphire substrate - Al2O3(0001). Obtaining the MXenes structures on carbon nanotubes allow to obtain new nanocomposites with extraordinary physicochemical properties which could be use in nanoelectronics.