Revealing the Impact of Alkaline Agents on the Photocatalytic Characteristics of Black Titanium Dioxide (TiO₂)

Black TiO2 owing to its fascinating photocatalytic properties has attracted research interest all around the world. Herein, the template-free hydrothermal method has been used to prepare black-TiO2 using different alkaline reagents (NaOH, NH4OH, LiOH, and KOH) to study their effect on the physiochemical properties. XRD, Raman spectroscopy, FESEM, EDX, UV-vis DRS, and PL investigations were carried out and comparatively discussed. The as-prepared black TiO2 has been subjected to photocatalytic degradation of methylene blue (MB) under visible light irradiation. Black TiO2 prepared from NH4OH displayed superior MB removal compared to others. The exceptional photocatalytic performance is attributed to its smaller band gap and enhanced porosity of the material. Meanwhile, black TiO2 prepared from KOH exhibited the least photocatalytic degradation capability due to abundant oxygen vacancies. Furthermore, the proposed mechanism highlights the effect of chemical reagents on the physiochemical properties of black TiO2 and describes the cause of poor photocatalytic behavior of KOH-based black TiO2 compared to others.