Two‐dimensional (2D) layered transition metal carbides/nitrides, called MXenes, are attractive alternative electrode materials for electrochemical energy storage. Owing to their metallic electrical conductivity and low ion diffusion barrier, MXenes are promising anode materials for sodium‐ion batteries (SIBs). Herein, we report on a new 2D carbonitride MXene, viz., Ti2C0.5N0.5Tx (Tx stands for surface terminations), and the only second carbonitride after Ti3CNTx so far. A new type of in situ HF (HCl/KF) etching condition was employed to synthesize multilayer Ti2C0.5N0.5Tx powders from Ti2AlC0.5N0.5. Spontaneous intercalation of tetramethylammonium followed by sonication in water allowed for large‐scale delamination of this new titanium carbonitride into 2D sheets. Multilayer Ti2C0.5N0.5Tx powders showed higher specific capacities and larger electroactive surface area than those of Ti2CTx powders. Multilayer Ti2C0.5N0.5Tx powders show a specific capacity of 182 mAh g−1 at 20 mA g−1, the highest among all reported MXene electrodes as SIBs with excellent cycling stability.
In this article, Michael Naguib and co‐authors (DOI: https://doi.org/10.1002/inf2.12269) report on the successful synthesis and characterization of a new 2D carbonitride MXene, viz. Ti2C0.5N0.5, which is the only second carbonitride MXene. They explore the performance of this new MXene as electrode materials for sodium‐ion batteries (SIBs) and it outperformed its carbide counterpart (i.e., Ti2C) and all the other reports for multi‐layer MXenes in SIBs and it showed a stable electrochemical performance over 500 cycles.
Here, a new family of 2D transition metal carbo‐chalcogenides (TMCCs) is reported, which can be considered a combination of two well‐known families, TM carbides (MXenes) and TM dichalcogenides (TMDCs), at the atomic level. Single sheets are successfully obtained from multilayered Nb2S2C and Ta2S2C using electrochemical lithiation followed by sonication in water. The parent multilayered TMCCs are synthesized using a simple, scalable solid‐state synthesis followed by a topochemical reaction. Superconductivity transition is observed at 7.55 K for Nb2S2C. The delaminated Nb2S2C outperforms both multilayered Nb2S2C and delaminated NbS2 as an electrode material for Li‐ion batteries. Ab initio calculations predict the elastic constant of TMCC to be over 50% higher than that of TMDC.
and high specific strength are required attributes. [1] CFRP composites have gained popularity, and they are already dominating the aerospace and wind energy industries. [2,3] CFRP incorporation in future transport vehicles, such as urban air mobility (UAM), is also growing. [4] CFRPs can replace their metal counterparts in applications where specific strength is desired but not in applications where other properties such as high electrical conductivity are required. Lightning strikes on aircraft and wind turbine structures are serious concerns, specifically, if the structures are made of CFRP composites. [5,6] During a lightning strike, a massive surge of electric current passes through the structures. If the structure does not possess enough electrical conductivity to dissipate the incident current, these structures can be destroyed due to the extreme amount of heat produced by the resistive heating or Joule's heating. [7] CFRP composites' low electrical conductivity (in through-thickness direction ≈ 0.01 S cm −1 ) makes them highly vulnerable to lightning strikes. [8] A common remedy is to protect the less-conductive CFRP using highly conductive coatings.Current commercial lightning strike protection (LSP) technologies in the aerospace industry are mainly composed of Ti 3 C 2 -a member of the MXenes (2D transition metal carbides and nitrides) family, is investigated as an effective filler to improve the electrical, mechanical, and thermal properties of divinylbenzene (DVB) thermosetting resin. Consequently, its performance as a lightning strike protection (LSP) coating for carbon fiber reinforced polymer (CFRP) is evaluated. Polyaniline (PANI)dodecylbenzene sulfonic acid (DBSA) complex is used to cure the DVB resin. The synergic effect of MXenes (with surface that is negatively charged) with polyaniline (positive charge) shows electrostatic bonding and improved electrical conductivity in the composite. The addition of MXenes at 2 wt% into the PANI-DVB composite shows ≈139%, 10%, and 9% improvement in electrical conductivity, flexural strength, and flexural modulus, respectively, compared to the neat PANI-DVB composite. The composites are investigated using various material characterization techniques including Fourier transforms infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Furthermore, MXenes-DVB is utilized to create a conductive thermosetting coating on top of a CFRP substrate and tested against a lightning strike of 100 kA. CFRP with MXenes-DVB coating reduced the surface damage from 40.61 cm 2 (reference CFRP panel) to 13.29 cm 2 (CFRP coated with MXenes-DVB).
MXene‐transition metal dichalcogenide (TMD) heterostructures are synthesized through a one‐step heat treatment of Nb2C and Nb4C3. These MXenes are used without delamination or any pre‐treatment. Heat treatments accomplish the sacrificial transformation of these MXenes into TMD (NbS2) at 700 and 900 °C under H2S. This work investigates, for the first time, the role of starting MXene phase in the derivative morphology. It is shown that while treatment of Nb2C at 700 °C leads to the formation of pillar‐like structures on the parent MXene, Nb4C3 produces nano‐mosaic layered NbS2. At 900 °C, both MXene phases, of the same transition metal, fully convert into nano‐mosaic layered NbS2 preserving the parent MXene's layered morphology. When tested as electrodes for hydrogen evolution reaction, Nb4C3‐derived hybrids show better performance than Nb2C derivatives. The Nb4C3‐derived heterostructure exhibits a low overpotential of 198 mV at 10 mA cm−2 and a Tafel slope of 122 mV dec−1, with good cycling stability in an acidic electrolyte.
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