Hydrothermal Synthesis of Iodine-Doped Nanoplates with Enhanced Visible and Ultraviolet-Induced Photocatalytic Activities

Abstract

The iodine-doped Bi2WO6(I-BWO) photocatalyst was prepared via a hydrothermal method using potassium iodide as the source of iodine. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of I-BWO for the degradation of rhodamine B (RhB) was higher than that of pure BWO and I2-BWO regardless of visible light (>420 nm) or ultraviolet light (<400 nm) irradiation. The results of DRS analysis showed that the I-BWO and I2-BWO catalysts had narrower band gaps. XPS analysis proved that the multivalent iodine species including I0and were coadsorbed on the defect surface of Bi2WO6in I-BWO. The enhanced PL intensity revealed that a large number of defects of oxygen vacancies were formed by the doping of iodine. The enhanced photocatalytic activity of I-BWO for degradation of RhB was caused by the synergetic effect of a small crystalline size, a narrow band gap, and plenty of oxygen vacancies.

Synthesis and photocatalytic properties of sunlight‐responsive BiOBr–CoWO4 heterostructured nanocomposites

“…The high‐resolution spectrum of W 4f orbital in CoWO 4 showed two intense peaks corresponding to binding energies of 32.87 and 35.06 eV due to W 4f 7/2 and W 4f 5/2 of CoWO 4 , respectively, showing that tungsten element is in the W 6+ oxidation state (Figure e). However, for BiOBr–CoWO 4 ‐2, the spectrum of W 4f orbital shows two peaks at 33.60 and 35.67 eV attributed to W 4f 7/2 and W 4f 5/2 of CoWO 4 , respectively, and an additional peak located at 27.35 eV was observed due to W 4f 7/2 orbital which indicates the lower oxidation state of tungsten element W 4+ in the composite . The formation of lower oxidation state W element in the composite may be due to adsorption of bromide ion on the surface defect sites of CoWO 4 nanoparticles in BiOBr–CoWO 4 ‐2 that changed the coordination environment of W. Figure f shows the XPS peak at a binding energy of 528.22 eV ascribed to O 1s present in BiOBr and CoWO 4 .…”

Tungsten-based nanomaterials (WO 3 & Bi 2 WO 6 ): Modifications related to charge carrier transfer mechanisms and photocatalytic applications

“…These rare earth ions (Er 3+ or Er 3+ :Y 3 A l5 O 12 ) with its upconversion properties transforms the visible light into UV light and activates the Bi 2 WO 6 to generate charge carriers. This approach is more beneficial, as the electron and hole with high potential would be available under the visible light, which is even beyond the absorption edge ofBi 2 WO 6 [222,223].The doping with nonmetal such as nitrogen, boron and iodine was beneficial to improve the photocatalytic activity, although boron doping failed to extend the visible light response for Bi 2 WO 6[224][225][226]. The boron doping could improve the acidity of the catalyst, thereby enabling the adsorption of the pollutants.…”

Sonochemical Synthesis, Characterization, and Photocatalytic Activity of N-Doped TiO2Nanocrystals with Mesoporous Structure

“…Compared with metal ions doping, nonmetal ions doping is environmentally friendly, which has less negative effect on the environment and ecosystem. Consulting the previous literatures [10][11][12][13][14], doping TiO 2 with nitrogen is one of the most effective means of narrowing the band gap and thus expands the light response range to visible light region. Surmacki et al prepared nitrogen doped TiO 2 powders by an electron beam irradiation method [10].…”

“…Numerous efforts have been directed towards the modification of TiO 2 by the incorporation of metal and nonmetal dopant ions in order to improve the photocatalytic activity under visible illumination [9][10][11][12][13][14]. Compared with metal ions doping, nonmetal ions doping is environmentally friendly, which has less negative effect on the environment and ecosystem.…”