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 y , Ti 1- y ) 2 CT x MXene in the treatment of water. Three different compositions of binary MXenes, viz., (Ti 0.75 Nb 0.25 ) 2 CT x , (Ti 0.5 Nb 0.5 ) 2 CT x , and (Ti 0.25 Nb 0.75 ) 2 CT x (with T x = OH, F, and Cl), were used as single-source precursor to produce TiNbO x -3:1, TiNbO x -1:1, and TiNbO x -1:3 by controlled-atmosphere thermal oxidation. Phase identification and Le Bail refinements confirmed the presence of a mixture of rutile TiO 2 and monoclinic Ti 2 Nb 10 O 29 . Morphological investigations through scanning and transmission electron microscopies revealed the retention of layered nanostructures from the MXene precursors and the fusion of TiO 2 and Ti 2 Nb 10 O 29 nanoparticles in forming nanosheets. Among the three oxide nanoheterostructures, TiNbO x -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 x -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.