A H₂O₂ Oxidation Approach to Ti₃C₂/TiO₂ for Efficient Photocatalytic Removal of Distinct Organic Pollutants in Water

To develop versatile photocatalysts for efficient degradation of distinct organic pollutants in water is a continuous pursuit in environment remediation. Herein, we directly oxidize Ti₃C₂ MXene with hydrogen peroxide to produce C-doped anatase TiO₂ nanowires with aggregates maintaining a layered architecture of the MXene. The Ti₃C₂ MXene provides a titanium source for TiO₂, a carbon source for in situ C-doping, and templates for nanowire aggregates. Under UV light illumination, the optimized Ti₃C₂/TiO₂ exhibits a reaction rate constant 1.5 times that of the benchmark P25 TiO₂ nanoparticles, toward photocatalytic degradations of trace phenol in water. The mechanism study suggests that photogenerated holes play key roles on the phenol degradation, either directly oxidizing phenol molecules or in an indirect way through oxidizing first the surface hydroxyl groups. The unreacted Ti₃C₂ MXene, although with trace amounts, is supposed to facilitate electron transfer, which inhibits charge recombination. The unique nanostructure of layered aggregates of nanowires, abundant surface oxygen vacancies arising from the carbon doping, and probably the Ti₃C₂/TiO₂ heterojunction guarantee the high photocatalytic efficiency toward removals of organic pollutants in water. The photocatalyst also exhibits an activity superior to, or at least comparable to, the benchmark P25 TiO₂ toward photodegradations for typical persistent organic pollutants of phenol, dye molecule of rhodamine B, antibiotic of tetracycline, pharmaceutical wastewater of ofloxacin, and pesticide of N,N-dimethylformamide, when evaluated in total organic carbon removal.