MXene-Derived Oxide Nanoheterostructures for Photocatalytic Sulfamethoxazole Degradation.

Herein, we report for the first time the use of ternary oxide nanoheterostructure photocatalysts derived from (Nb , Ti )CT MXene in the treatment of water. Three different compositions of binary MXenes, viz., (TiNb)CT , (TiNb)CT , and (TiNb)CT (with T = OH, F, and Cl), were used as single-source precursor to produce TiNbO -3:1, TiNbO -1:1, and TiNbO -1:3 by controlled-atmosphere thermal oxidation. Phase identification and Le Bail refinements confirmed the presence of a mixture of rutile TiO and monoclinic TiNbO. Morphological investigations through scanning and transmission electron microscopies revealed the retention of layered nanostructures from the MXene precursors and the fusion of TiO and TiNbO nanoparticles in forming nanosheets. Among the three oxide nanoheterostructures, TiNbO -3:1 exhibited the best photocatalytic performance by the removal of 83% of sulfamethoxazole (SMX) after 2 h of reaction. Such a result is explained by a complex influence of structural, morphological, and electronic properties since TiNbO -3:1 consisted of small-sized crystallites (40-70 nm) and possessed a higher surface area. The suggested electronic band structure is a type-II heterojunction, where the recombination of electrons and holes is minimized during photocatalytic reactions. The photocatalytic degradation of SMX was promoted by the attack of OH, as evidenced by the detection of 2.2 μM OH, using coumarin as a probe. This study highlights the potential application of MXene-derived oxide nanoheterostructures in wastewater treatment.