By Surbhi Jain, June 28, 2022, reviewed by Susha Cheriyedath, M.Sc.
In a recent article in the journal Materials Chemistry and Physics, the researchers discussed a paradigm shift in MXene synthesis through rapid microwave-assisted etching and delamination of phase MAX.
Study: microwave-assisted rapid etching and delamination of MAX phase: a paradigm shift in MXene synthesis. Image credit: Sergey Nivens / Shutterstock.com
MXenes: Exceptional 2D materials
Among the families of two-dimensional (2D) materials, the carbides, carbonitrides, and nitrides of transition metals, collectively known as MXenes, have made remarkable advances. The MXene surface invariably ends with surface fragments after selective etching (Tx, terminal groups). As a result, it is known as Mn + 1XnTx, with T denoting the terminal group.
Due to its exceptional electrical conductivity, layered structure, hydrophilicity and excellent transmittance, this new class of 2D materials has demonstrated excellent potential in a variety of applications, such as solar cells, batteries, storage of hydrogen, supercapacitors and catalysts, among others. It should be noted that there are significant environmental and time requirements for selectively recording element “A” of the MAX phase.
In recent years, several initiatives have been taken to reduce environmental risks. Although these procedures replaced HF solutions to reduce operational risk, a reaction time of up to 48 hours remains a barrier to mass manufacture and use of MXenes. Therefore, it is highly desirable to create a simple, fast and environmentally friendly MXene production process.
MXene synthesis by etching and delamination in MAX phase
In this study, the authors described the delamination of MAX phase MXene sheets as a unique and rapid process. In the current approach, aluminum (Al) was etched from the MAX phase in two hours after processing, with a time reduction of up to 48 hours and a temperature reduction of 180 to 40 degrees Celsius.
The characteristics of the MXene were assessed using a variety of characterizations. Typical Ti3C2Tx spectra derived from Ti3AlC2 after rapid Al etching were acquired in the X-ray photoelectron (XPS) and X-ray diffraction (XRD) spectroscopy patterns. To complement these findings, scanning and transmission electron microscopy (SEM and TEM), visible ultraviolet (UV) absorption spectra, and Brunauer-Emmett-Teller (BET) absorption and desorption curves were used.
The team proposed a simple, new and fast way to make MXene. In a microwave synthesizer, the etching time was reduced to almost 30 minutes with a LiF / HCl solution. In addition, during microwave heating, the nucleation of Li atoms in the interlayer space of the MAX Ti3AlC2 phase resulted in the washing process, which removed the Al atoms from the Ti3AlC2 sites. Fully delaminated MXene sheets were created using this simple and creative process.
The researchers presented a new and substantially greener way to etch the delamination of Al and MXene sheets from the Ti3AlC2 MAX phase to address the complication of high temperature and prolonged time associated with traditional Al etching methods. .
To achieve this goal, Ti3C2Tx – MXene was created by rapidly etching Al of the MAX phase over about two hours at a temperature of 40 degrees Celsius using a unique microwave-assisted hydrothermal technique.
MXens of high quality in a shorter time
The creation of Ti3C2Tx was confirmed by XRD spectra and XPS results on surface composition supported XRD findings. All elements commonly seen in the Ti3C2Tx MXene were visible in the deconvolved XPS spectra for O 1s, Ti 2p, and C 1s. In addition, SEM, TEM and associated mapping studies demonstrated how high-quality MXene was produced from the MAX phase.
Visible UV absorption data and BET absorption and desorption curves supported the creation of high quality MXene. As a result, in a remarkably shorter processing time, high-quality MXene with smaller traces of Al was created, which demonstrated the effectiveness of the approach used in the current work.
The proposed technique could produce a variety of 2D Mn + 1Xn structures, which include Zr, Ti, Nb, Ta, V, Cr and Hf carbides and nitrides. In addition, the discovered technology could open the door to a faster, large-scale, and more environmentally friendly MXene production process that could also be applied to other 2D materials.
Conclusions
In conclusion, this study elucidated the use of a LiF / HCL mixture to reduce the toxicity of the usual Al etching procedures based on HF solution. Analysis of the synthesized MXene showed that there was almost no extraction of Al atoms, which supported the efficiency of the current process for simple, environmentally friendly, fast and expanded synthesis. of MXene.
The results showed the creation of high-quality MXene with barely detectable traces of Al, which testifies to the effectiveness of the current approach.
The authors believe that this study offers new opportunities for the use of MXene in the industry, as well as establishing a comprehensive approach to producing it quickly and in large quantities.
Reference
Numan, A., Rafique, S., Khalid, M., et al. (2022) Microwave-assisted etching and rapid delamination of phase MAX: a paradigm shift in MXene synthesis. Chemistry and Physics of Materials 126429. https://www.sciencedirect.com/science/article/pii/S0254058422007350?via%3Dihub
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