Black TiO_x Films with Photothermal-Assisted Photocatalytic Activity Prepared by Reactive Sputtering

Titanium oxide is widely applied as a photocatalyst. However, its low efficiency and narrow light absorption range are two main disadvantages that severely impede its practical application. In this work, black TiO_x films with different chemical compositions were fabricated by tuning target voltage and controlling O₂ flow during reactive DC magnetron sputtering. The optimized TiO_x films with mixed phases (TiO, Ti₂O₃, Ti₃O₅, and TiO₂) exhibited fantastic photothermal and photocatalytic activity by combining high light-absorptive Ti₂O₃ and Ti₃O₅ phases with the photocatalytic TiO₂ phase. The sample prepared with oxygen flow at 5.6 ± 0.2 sccm and target voltage near 400 V exhibited excellent optical absorbance of 89.29% under visible light, which could improve surface temperature to 114 °C under sunlight. This film could degrade Rhodamine-B up to 74% after 150 min of UV irradiation. In a word, this work provides a guideline for fabricating black TiO_x films with photothermal-assisted photocatalytic activity by reactive DC magnetron sputtering, which could avoid the usage of hydrogen and is convenient for quantity preparation.