UV and Visible Light-Driven Production of Hydroxyl Radicals by Reduced Forms of N, F, and P Codoped Titanium Dioxide

Abstract

The photocatalytic activities of reduced titanium dioxide (TiO2) materials have been investigated by measuring their ability to produce hydroxyl radicals under UV and visible light irradiation. Degussa P25 TiO2 was doped with nitrogen (N), fluorine (F), and/or phosphorus (P) and then subjected to surface modification employing a thermo-physicochemical process in the presence of reducing agent sodium borohydride (NaBH4). The reduced TiO2 materials were characterized by a number of X-ray, spectroscopic and imaging methods. Surface doping of TiO2 was employed to modulate the band gap energies into the visible wavelength region for better overlap with the solar spectrum. Hydroxyl radical generation, central to TiO2 photocatalytic water purification applications, was quantitated using coumarin as a trap under UV and visible light irradiation of the reduced TiO2 materials. At 350 nm irradiation, the yield of hydroxyl radicals generated by the reduced forms of TiO2 was nearly 90% of hydroxyl radicals generated by the Degussa P25 TiO2. Hydroxyl radical generation by these reduced forms of TiO2 was also observed under visible light irradiation (419 and 450 nm). These results demonstrated that simple surface modification of doped TiO2 can lead to visible light activity, which is important for more economical solar-driven applications of TiO2 photocatalysis.

Photocatalytic Reforming of Sucrose and Dextrose for Hydrogen Production on Pd/TiO2

“…The catalysts were analyzed before and after the reaction for comparison purposes (Figure 6). Table 1 shows a band at 139.5 cm −1 corresponds to the symmetric stretching vibration of O−Ti−O of TiO 2, which is slightly lower than values reported (142.9) in the literature [48] . The shift in the E g band position between fresh and used TiO 2 can be attributed to changes in Ti 4+ symmetry [49] .…”

“…Table 1 shows a band at 139.5 cm À 1 corresponds to the symmetric stretching vibration of OÀ TiÀ O of TiO 2, which is slightly lower than values reported (142.9) in the literature. [48] The shift in the E g band position between fresh and used TiO 2 can be attributed to changes in Ti 4 + symmetry. [49] Introducing 0.25 %Pd resulting E g band undergo a redshift from 139.5 to 143.7.…”

Visible-Light Active Titanium Dioxide Nanomaterials with Bactericidal Properties

“…Moreover, the conduction band can transfer electrons to the oxygen vacancies. This cascade effect facilitates the continuous generation of superoxide anion and hydroxide radical species [268,269]. The ROS then cause the destruction and death of microorganisms accordingly.…”

Photocatalytic Treatment of Stained Wastewater Coming from Handicraft Factories. A Case Study at the Pilot Plant Level

“…The potential toxicity of this oxide must also be considered in its application on a large scale [6]. This high energy gap (3.23 eV) material needs ultraviolet light to be excited to produce hydroxyl radicals [7], but sunlight only consists of 5% ultraviolet light [8], resulting in a challenge for using TiO 2 under environmental conditions. However, in the present study we selected this oxide only as a reference material to achieve the removal of heavy metals by photochemical reduction.…”