Black titanium dioxide nanomaterials for photocatalytic removal of pollutants: A review

Semiconductor photocatalysis is one of the most widely used environment-friendly technologies for removing various contaminants. As a well-developed photocatalyst, titanium dioxide (TiO2) still has limits in its wide bandgap and rapid recombination rate of photogenerated charge carriers. Recently, black TiO2 appears as a strong candidate in the improvement of sunlight harvesting, because of its excellent absorption capacity and utilization of solar radiation. Despite extensive applications in both environmental and energy fields, the use of black TiO2 as a photocatalyst in pollutant removal is ambiguous. The primary objective of the review is to comprehensively evaluate the applications of black TiO2 in photocatalytic removal of contaminants, including conventional organic contaminants, emerging contaminants, microbes, and heavy metals. The basic properties, photocatalytic mechanism, and synthesis of black TiO2 have been summarized and analyzed. Moreover, the stability and recoverability of black TiO2 have also been discussed. Finally, the perspectives of the application of black TiO2 in pollutant removal have been further discussed.