Etching-dependent structure and catalytic performance of Ti₃C₂Tₓ MXene for oxidative desulfurization of dibenzothiophene

The synthesis route of MXenes plays a crucial role in determining their structural characteristics and catalytic performance. In this work, Ti₃C₂Tₓ MXenes synthesized via conventional hydrofluoric acid (HF) etching and a mild in-situ LiF/HCl etching route were comparatively evaluated as catalysts for the oxidative desulfurization (ODS) of dibenzothiophene (DBT) using tert-butyl hydroperoxide, without additional active-metal modification. Structural characterizations confirmed successful conversion of Ti₃AlC₂ MAX phase into Ti₃C₂Tₓ MXene through both etching methods. Compared with HF etching, LiF/HCl produced MXene with a larger interlayer spacing (1.21 nm), higher pore volume (0.027 cm 3 .g −1 ), and more pronounced oxygen-containing surface functionalities, despite its lower BET surface area (11.8 vs. 15.5 m 2 .g −1 ). These structural differences markedly influenced the ODS performance. Under optimum conditions (120 °C, O/S = 4, catalyst dosage = 0.25 g.L −1 ), the LiF/HCl-derived MXene achieved complete DBT removal, whereas HF-derived MXene and pristine Ti₃AlC₂ reached 84% and 25% removal, respectively. The catalyst retained 91% of its initial activity after five recycling, and GC–MS confirmed DBTO 2 as the final oxidation product. The superior performance of the LiF/HCl-derived MXene is attributed to its favorable interlayer structure and surface chemistry, highlighting controlled etching as an effective strategy for designing efficient MXene catalysts for ultra-deep ODS.