Black titanium dioxide (TiO₂) nanomaterials

Abstract

In the past few decades, there has been a wide research interest in titanium dioxide (TiO2) nanomaterials due to their applications in photocatalytic hydrogen generation and environmental pollution removal. Improving the optical absorption properties of TiO2 nanomaterials has been successfully demonstrated to enhance their photocatalytic activities, especially in the report of black TiO2 nanoparticles. The recent progress in the investigation of black TiO2 nanomaterials has been reviewed here, and special emphasis has been given on their fabrication methods along with their various chemical/physical properties and applications.

Hydrogenated TiO2/SrTiO3 porous microspheres with tunable band structure for solar-light photocatalytic H2 and O2 evolution

“…5a shows the UV-Vis absorption spectra of the different samples. TiO2 and SrTiO3 have an absorption edge around 400 nm, which is consistent with traditional rutile TiO2 [27,25] and perovskite SrTiO3 [26] semiconductors, suggesting that the light irradiation for photocatalysis should derive mainly from UV light. The TiO2/SrTiO3 composite exhibits absorption up to ca.…”

“…This indicates that the water-splitting reaction over the samples is associated with the DRS absorption spectra [44]. Compared with other typical TiO2/SrTiO3 nanostructures with different morphologies [26,[30][31][32][33][34], the H-TiO2/SrTiO3 heterostructured porous microspheres present much higher photocatalytic activity. This can be attributed to the synergistic effect of the unique porous sphere structure, heterostructure, and appropriate oxygen-vacancy and Ti 3+ contents, which serve as trapping sites, preventing the rapid recombination of charge carriers and improving the interfacial electron-transfer rate and the migration efficiency of photoinduced electrons.…”

“…9. As described in previous reports [24,26], hydrogenation leads to the formation of an isolated band within the band gap, which causes the band edge to red-shift toward the longer wavelength region, indicating a narrowing of the band gap [25,45]. Under visible-light irradiation, the photogenerated electrons in the covalence band of H-TiO2 and H-SrTiO3 are both excited and transferred to the corresponding conduction band (CB) (process 4).…”

“…The enhanced light absorption of the H-TiO2/SrTiO3 heterostructured porous microspheres leads to the production of more electron-hole pairs under the same visible-light irradiation. Furthermore, the surface-localized oxygen vacancies strongly influence the electronic structure, which results in higher photocatalytic activity [26].…”

“…Furthermore, the disordered layer produced can significantly enhance visible-light absorption [25]. The exploitation of oxygen vacancies in hydrogenated semiconductors provides new strategies to control their charge separation process and electronic structures [26,27]. Thus, this methodology can be used to maximize the advantages of the wide range of semiconductor photocatalysts while minimizing their disadvantages.…”