Effective Photocatalytic Activity of Sulfate-Modified BiVO4 for the Decomposition of Methylene Blue Under LED Visible Light

Abstract

In this study, we investigated sulfate-modified BiVO4 with the high photocatalytic activity synthesized by a sol-gel method in the presence of thiourea, followed by the annealing process at different temperatures. Its structure was characterized by thermal gravimetric analysis (TGA), powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). The BiVO4 synthesized in the presence of thiourea and calcined at 600 °C (T-BVO-600) exhibited the highest photocatalytic degradation efficiency of methylene blue (MB) in water; 98.53% MB removal was achieved within 240 min. The reaction mechanisms that affect MB photocatalytic degradation on the T-BVO-600 were investigated via an indirect chemical probe method, using chemical agents to capture the active species produced during the early stages of photocatalysis, including 1,4-benzoquinone (scavenger for O2−), ethylenediaminetetraacetic acid disodium salt (scavenger for h+), and tert-butanol (scavenger for HO•). The results show that holes (h+) and hydroxyl radicals (HO•) are the dominant species of MB decomposition. Photoluminescence (PL) measurement results of terephthalic acid solutions in the presence of BiVO4 samples and BiVO4 powders confirm the involvement of hydroxyl radicals and the separation efficiency of electron-hole pairs in MB photocatalytic degradation. Besides, the T-BVO-600 exhibits good recyclability for MB removal, achieving a removal rate of above 83% after five cycles. The T-BVO-600 has the features of high efficiency and good recyclability for MB photocatalytic degradation. These results provide new insight into the purpose of improving the photocatalytic activity of BiVO4 catalyst.

BiVO4–Deposited MIL–101–NH2 for Efficient Photocatalytic Elimination of Cr(VI)

“…Confirming the effective preparation of pure BiVO 4 , BV displaying narrow line width peaks can be indexed to the high crystallinity monoclinic BiVO 4 (JCDPDS Card No. 83–1699) [ 22 , 28 ]. Moreover, the detection of any peaks can be ascribable to other phases or impurities.…”

Effect of sulfur doping on the photocatalytic performance of sputtered BiVO4 thin films

“…2(b)] can be assigned to S 2− species in BiVO 4 . 20,[23][24][25] The S2s peak of the S 11 -BiVO 4 sample in the higher binding energy region (∼236 eV) compared to the peak lower binding energy position (∼233.2 eV) may be assigned as S 8 26) or sulphate (SO 4 ) and sulfide (S 2− ), [27][28][29] respectively. The peak shift in the S 11 -BiVO 4 sample, at ∼233.2 eV, can be estimated by the changes in the band gap by doping sulfur into BiVO 4 .…”

Visible Domain Photocatalysis Performance of Ti-Si Thermal-Sprayed Coatings

“…It could be concluded that, in the case of the coating deposited on steel, a concurrent photo-Fenton process could also occur, due to the formation of the Fe 2+ ion from the oxidation of the metallic substrate. The addition of isopropyl alcohol (OH radical scavenger) determines a significant decrease in the photocatalysis efficiency, evidencing the critical role of the hydroxyl radical in methylene blue degradation, possibly via Mechanism (4), where MBH denotes the methylene blue dye in its non-oxidized form and MB the smaller molecular compounds, which could be formed during the initial stages of photodegradation [49,50]. Superoxide radicals seem to play a marginal role in the visible-light-aided degradation of MB since no significant decrease in the photocatalysis efficiency was registered by the addition of the ascorbic acid scavenger [51,52].…”