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1. Oxidation stability of Ti3C2Tx MXene nanosheets in solvents and composite films

   https://doi.org/10.1038/s41699-019-0089-3  

   Habib, Touseef; Zhao, Xiaofei; Shah, Smit A.; Chen, Yexiao; Sun, Wanmei; An, Hyosung; Lutkenhaus, Jodie L.; Radovic, Miladin; Green, Micah J. (February 2019, npj 2D Materials and Applications)

   Abstract Ti₃C₂T_xbelongs to the family of MXenes, 2D materials with an attractive combination of functional properties suitable for applications such as batteries, supercapacitors, and strain sensors. However, the fabrication of devices and functional coatings based on Ti₃C₂T_xremains challenging as they are prone to chemical degradation by their oxidation to TiO₂. In this paper, we examine the oxidation of Ti₃C₂T_xin air, liquid, and solid media via conductivity measurements to assess the shelf life of Ti₃C₂T_xMXenes. The oxidation of Ti₃C₂T_xwas observed in all the media used in this study, but it is fastest in liquid media and slowest in solid media (including polymer matrices). We also show that the conventional indicators of MXene oxidation, such as changes in color and colloidal stability, are not always reliable. Finally, we demonstrate the acceleration of oxidation under exposure to UV light. 

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2. Adsorption of selected dyes on Ti3C2Tx MXene and Al-based metal-organic framework

   https://doi.org/10.1016/j.ceramint.2019.09.293  

   Jun, Byung-Moon; Heo, Jiyong; Taheri-Qazvini, Nader; Park, Chang Min; Yoon, Yeomin (February 2020, Ceramics International)
3. First-principles study of hydrogen storage application of Ti3C2Tx monolayer MXene

   https://doi.org/10.1016/j.ijhydene.2024.01.136  

   Chu, Yi Zhi; Lau, Kah Chun (February 2024, International Journal of Hydrogen Energy)

   MXene, with its high aspect ratio and adjustable surface properties, has garnered significant attention in the realm of hydrogen storage research. For the first time, considering a ternary/quaternary mixed terminated MXene surface, the authors have investigated comprehensively the hydrogen storage potential of two-dimensional (2D) titanium carbide Ti3C2Tx monolayer MXene using density functional theory (DFT). By considering mixed terminated surfaces, this study indicated the locally induced dipole due to the mixed termination is beneficial in facilitating hydrogen adsorption with stronger average adsorption energies than that of the uniform F-/O-/OH-/H-terminated surfaces. The authors estimated a compelling average H2 surface adsorption energy on the ternary mixed termination and total surface storage capacity to be −0.14 eV/H2 and ∼2 wt% H2, which is comparable to that of the metal-organic frameworks (MOFs). This study also reveals the importance of the local surface chemistry effects on hydrogen adsorption. 

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4. Layer-Dependent Gas Sensing Mechanism of 2D Titanium Carbide (Ti3C2Tx) MXene

   https://doi.org/10.1021/acsnano.4c08225  

   Loes, Michael J; Bagheri, Saman; Sinitskii, Alexander (September 2024, ACS Nano)

   Monolayers of Ti3C2Tx MXene and bilayer structures formed by partially overlapping monolayer flakes exhibit opposite sensing responses to a large scope of molecular analytes. When exposed to reducing analytes, monolayer MXene flakes show increased electrical conductivity, i.e., an n-type behavior, while bilayer structures become less conductive, exhibiting a p-type behavior. On the contrary, both monolayers and bilayers show unidirectional sensing responses with increased resistivity when exposed to oxidizing analytes. The sensing responses of Ti3C2Tx monolayers and bilayers are dominated by entirely different mechanisms. The sensing behavior of MXene monolayers is dictated by the charge transfer from adsorbed molecules and the response direction is consistent with the donor/acceptor properties of the analyte and the intrinsic n-type character of Ti3C2Tx. In contrast, the bilayer MXene structures always show the same response regardless of the donor/acceptor character of the analyte, and the resistivity always increases because of the intercalation of molecules between the Ti3C2Tx layers. This study explains the sensing behavior of bulk MXene sensors based on multiflake assemblies, in which this intercalation mechanism results in universal increase in resistance that for many analytes is seemingly inconsistent with the n-type character of the material. By scaling MXene sensors down from multiflake to single-flake level, we disentangled the charge transfer and intercalation effects and unraveled their contributions. In particular, we show that the charge transfer has a much faster kinetics than the intercalation process. Finally, we demonstrate that the layer-dependent gas sensing properties of MXenes can be employed for the design of sensor devices with enhanced molecular recognition. 

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5. Electrochemical Amyloid β Immunosensor Based on Ti3C2Tx MXene Nanosheets

   https://doi.org/10.1093/mam/ozae044.459  

   Garcia, Antonio S; Locke, Angelina K; Core, Bryson D; Gautam, Bhoj R; Autrey, Daniel E; Han, Shubo (July 2024, Microscopy and Microanalysis)