Rapid synthesis of MXenes using LiF + HCl etchant beyond Ti₃AlC₂

Synthesis of MXenes remains challenging, especially for MAX phases beyond titanium-based systems. Among the available methods, LiF + HCl etching has proven to be the most effective, optimized for Ti₃AlC₂ and later extended to mixed-metal phases (e.g., Mo₂Ti₂AlC₃) and non-titanium phases (e.g., V₂AlC). These advances have enabled the production of larger, higher-quality MXene sheets; however, the method still faces two key drawbacks: (i) prolonged etching times (≥24 h) and (ii) oxidation of the final product, which limits both structural integrity and practical use. Herein, we report, for the first time, a rapid hydrothermal LiF + HCl etching strategy that reduces synthesis time to only 2 h at 140 °C, a significant improvement over conventional protocols that require ≥24 h. The accelerated process minimizes oxidation while maintaining high etching efficiencies of ∼74%, ∼86%, and ∼92% for Ti₃C₂, V₂C, and Mo₂Ti₂C₃, respectively, demonstrating applicability beyond Ti-based MAX phases. The etched products were readily delaminated into few-layer MXene sheets within a few minutes of ultrasonication. Comprehensive characterization using XRD, SEM, TEM, and XPS confirmed the successful formation of MXenes, with etched layered morphologies and preservation of carbide bonding. The colloidal behavior of the derived MXenes has been assessed through DLS analysis and zeta potential measurements, revealing consistently high colloidal stability. Notably, the dispersions exhibited months-long colloidal stability without significant degradation. Such stability, combined with reduced processing time, represents a crucial step toward scalable, long-term MXene applications in energy storage, catalysis, and other advanced technologies.