Defective Grey TiO2 with Minuscule Anatase–Rutile Heterophase Junctions for Hydroxyl Radicals Formation in a Visible Light-Triggered Photocatalysis

Abstract

The novelty of this work was to prepare a series of defect-rich colored TiO2 nanostructures, using a peroxo solvothermal-assisted, high-pressure nitrogenation method. Among these solids, certain TiO2 materials possessed a trace quantity of anatase–rutile heterojunctions, which are beneficial in obtaining high reaction rates in photocatalytic reactions. In addition, high surface area (above 100 m2/g), even when utilizing a high calcination temperature (500 °C), and absorption of light at higher wavelengths, due to the grey color of the synthesized titania, were observed as an added advantage for photocatalytic hydroxyl radical formation. In this work, we adopted a photoluminescent probe method to monitor the temporal evolution of hydroxyl radicals. As a result, promising hydroxyl radical formations were observed for all the colored samples synthesized at 400 and 500 °C, irrespective of the duration of calcination.

Synthesis of Cu-Doped TiO2 Nanocatalyst for the Enhanced Photocatalytic Degradation and Mineralization of Gabapentin under UVA/LED Irradiation: Characterization and Photocatalytic Activity

“…BET analysis estimated the surface areas of prepared TiO2 and Cu-TiO2 to be 52.1 a 9.9 m 2 /g, respectively (Figure 3). It can be related to changes in the morphology and cr talline structure of the TiO2 after doping with Cu [30]. This result agreed with Tasbih al.…”

“…talline structure of the TiO2 after doping with Cu [30]. This result agreed with Tasbihi et al [34] and Bensouici et al [22], who reported a decrease in the surface area of TiO2 after doping with Cu.…”

“…The medium peaks at about 3485 and 3500 cm −1 confirm the presence of OH bands in the sample structure due to surface adsorb water and hydroxyl agent. The vibration bands are observed between 1000 to 1250 cm −1 after Cu-doped TiO2 indicated lattice vibration of TiO2 [29][30][31][32].…”

“…Therefore, the low band gap of CuO (1.7 eV) compared to TiO 2 (3.2 eV) is a reason for driving photo-generated electrons from the CB of metallic copper to TiO 2 , and at the same time, photo-induced holes jumped from the VB TiO 2 to VB CuO [13]. On the other hand, the synergistic role between anataserutile heterophase in the as-prepared catalyst induced the separation of electron-hole pairs accelerated for the greater transfer of photo agents in the CB and VB of Cu-TiO 2 nanoparticles (Equations ( 2)-( 5)) [30].…”

Synthesis and Applications of TiO2‐based Nanostructures as Photocatalytic Materials

“…Anatase TiO 2 is an indirect bandgap semiconductor, and electrons in the conduction band need to undergo a shift to recombine with holes in the valence band, which inhibits the recombination of electron-hole pairs and thus has high photocatalytic activity. Moreover, In order to obtain photocatalysts that can have better light absorption, the materials can be treated by other means such as hydrogenation or doping, while their color changes to black, [29][30][31][32] blue, [33,34] brown, [35][36][37] red, [38,39] yellow, [40,41] grey, [42][43][44] etc.…”