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Industrial scaleup of MXene synthesis has faced many challenges, both in the process safety and nanosheet yield. As a step toward the scalability of MXenes, we carried out a one-to-one comparison of the industrial scalability and application performance of two methods for producing Ti3C2Tz MXenes: LiF-HCl acid etching and Lewis acid molten salt etching. This study had an emphasis on nanoscale structure, electrical conductivity, electromagnetic interference (EMI) shielding and supercapacitive properties, yield, and process scalability, both at the etched clay stage and delaminated nanosheet stage. This comparison was completed in parallel with the same starting MAX phase, chemicals, and processing equipment, where necessary. The synthesis process influences the structure and terminal groups of MXenes, altering properties and performance. Notably, the electrical conductivity was superior for acid-etched nanosheets at 2200 S/cm, compared to salt-etched nanosheets at 0.66 S/cm. For EMI shielding effectiveness and capacitance, acid-etched nanosheets performed the highest. The yield of the acid-etched nanosheets was ~ 50% and salt-etched nanosheets was 15%. The acid-etched process was scaled up with a small business partner from 1-g to 200-g MAX phase, with similar properties and yield. When the salt-etching process was scaled up to 25 g of MAX, the properties remained similar to the 1 g batch, with a lower yield of ~ 5%. Although the acid-etching process was better for most metrics, the molten salt-etching method is still in its infancy and has advantages regarding process safety. 

Rapid, out‐of‐oven techniques for MXene synthesis are of great interest and would allow for easier production of this exciting class of 2D materials. MXenes are typically synthesized by etching MAX phases with strong acids for long times, sometimes exceeding 40 h. Electrothermal synthesis techniques can reduce the heating time of materials; here Joule heating with molten salt etching precursors is utilized to etch MAX phase into multilayered (ML) Ti₃C₂T_x MXenes. An inert environment is used to etch the MAX phase in 30 min at 750–800 °C. SEM/EDS and XRD confirmed etching of the material. XPS, FTIR, and Raman are compared to conventional LiF‐HCl ML‐ Ti₃C₂T_x, showing similar spectra to Joule heated ML‐Ti3C2Tx material. Most importantly, this new out‐of‐oven Ti₃C₂T_x synthesis decreased etching time by 98% from molten salt etching and reduced energy usage from 1.56 × 10⁷to 1.01 × 10⁶J g⁻¹per batch, paving the way for the commercialization of MXene etching. 

Not AvailableIntercalation in two-dimensional (2D) materials can modify their physical, chemical, and electronic properties. This modification enables the tailoring of 2D material characteristics, enhancing their performance and expanding their applications in various fields. The friction performance of 2D materials such as MoS2 and graphite has a strong dependence on their interlayer spacing, and they exhibit an increase in d-spacing associated with a reduction in friction performance. The ability to control the interlayer spacing of Ti3C2Tz MXene has proven beneficial for energy storage applications such as batteries and supercapacitors, but no one has utilized this control of interlayer spacing for lubrication. In this study, we demonstrate that interlayer spacing of multilayer (ML) Ti3C2Tz MXene can be controlled through chemical intercalation and its direct effects on the electrical conductivity and friction performance. We observed a notable decrease in electrical conductivity in vacuum-filtered ML-Ti3C2Tz MXene films, which was attributed to an increased internal resistance resulting from the expansion of the interlayer gap. We also found a significant reduction in the coefficient of friction for ML-Ti3C2Tz MXene with an increased d-spacing. This reduction is attributed to a weakened attraction of individual ML-Ti3C2Tz MXene layers (intercalated). Under a tangential force, it becomes easier to slide within the larger interlayer gap with weakened van der Waals forces. This work provides insights into the tunability of MXene properties through interlayer spacing, offering potential applications requiring materials with specific electrical and friction characteristics.