Contemporary Developments of Black TiO2 Nanophotocatalysts for the Degradation of Agrochemical Pollutants

Pesticide-contaminated wastewater treatment has become a hotly debated topic in recent years. Titanium dioxide is the most widely used photocatalyst that effectively uses UV radiation. The recent advancement in black TiO2 nanomaterials clearly demonstrated that structural and morphological traits and appropriate electrical properties are widely used in many research areas. The associated drawbacks of white TiO2 and its modified forms were addressed largely after the discovery of black titania (B-TiO2) because it not only absorbs photons in a broad spectral range (UV to IR region) but also significantly boosts the catalytic performance. The photocatalytic properties of titanium oxide are closely related to material defect disorders, such as oxygen vacancy and Ti3+ defect. Defective nanoparticles with superior properties to white TiO2 and efficient solar harvest in the photocatalytic application were synthesized by various reduction and oxidation approaches and various characterization techniques such as XRD, DRS, XPS, SEM, TEM, and so on were applied to investigate the properties of the defective TiO2. The enhanced photoactivity can be explained on the basis of various defects associated with the black TiO2. Photocatalytic activity of black titanium oxide under visible light was over 90% of imidacloprid degradation for example and can be associated with the specific surface area, bandgap energy smaller than white TiO2, a large amount of surface defect Ti3+, and oxygen vacancies that promote charge carriers’ separation.