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Author: search.filters.author.Wechprasit, TirapatSubject: search.filters.subject.Bismuth vanadate

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    STRUCTURAL, OPTICAL, AND VISIBLE-LIGHT DRIVEN PHOTACATALYTIC PROPERTIES OF Yb-DOPED BiVO4 NANOPARTICLES PREPARED VIA RAPID SONOCHEMICAL PROCESS
    (2023-01-01)
    Boonyarattanakalin, Kanokthip
    ;
    Noinonmueng, Tanisara
    ;
    Kansaard, Thanaphon
    ;
    Wechprasit, Tirapat
    ;
    Mekprasart, Wanichaya
    This work represents the synthesis and structural, morphological, and optical characterization of rare-earth Yb-doped BiVO<inf>4</inf> materials with different Ytterbium (Yb<sup>3+</sup>) contents (0% - 5%). Yb-doped BiVO<inf>4</inf> specimens in form of fine nanoparticles were synthesized by a rapid and facile sonochemical process. The structural and morphological characterizations were observed by X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Important optical properties of the prepared samples were investigated by the diffuse reflectance technique and the corresponding optical band gaps were calculated by the mean of the Kullbelka-Munk equation. From the characterized results, it is acknowledged that incorporated Yb dopant has a significant effect on the crystalline structure of BiVO<inf>4</inf> by reducing in monoclinic phase in the pristine sample while the increasing Yb doping composition resulted in the mixed phases of monoclinic and tetragonal phases since Yb<sup>3+</sup> ions could probably induce the stabilization of the tetragonal phase in BiVO<inf>4</inf> material. Moreover, extensive doping with Yb<sup>3+</sup> exhibits considerable influence on not only structural but also optical and relevant visible - driven photocatalytic properties of BiVO<inf>4</inf> by means of the color degradation of RhB dye solution
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    Structural and Optical Properties of Mn-Incorporated BiVO4 Nanoparticles Synthesized by Sonochemical Process
    (2022-01-01)
    Wechprasit, Tirapat
    ;
    Kansaard, Thanaphon
    ;
    Bootchanont, Atipong
    ;
    Pecharapa, Wisanu
    In this work, Mn-incorporated BiVO<inf>4</inf> nanoparticles with different Mn contents (0–5%) were synthesized by one-step sonochemical process. Structural phase of Mn-incorporated BiVO<inf>4</inf> nanoparticles was extensively carried out by X-ray diffraction technique. The XRD results show that the structural phase of BiVO<inf>4</inf> belongs to the monoclinic principal structure while the secondary phases of MnO, Mn<inf>2</inf>O<inf>3</inf>, and Mn<inf>3</inf>O<inf>4</inf> structures are noticed in Mn-loaded samples. Chemical bondings of Mn-incorporated BiVO<inf>4</inf> nanoparticles were characterized with Raman spectroscopy. Relevant chemical bondings confirm the existence of VO<inf>4</inf><sup>3−</sup> tetrahedron and the V–O band by Raman spectra. Diffuse reflection spectroscopy and FE-SEM were employed to examine their optical and morphological properties, respectively. The results indicate that the incorporation of Mn can induce the red-shift of optical absorption edge in visible range, which can decrease the optical band gap of BiVO<inf>4</inf>. Morphology of all samples demonstrates the difference in shape of the compounds with the incorporation of Mn contents. Oxidation number and local structure of Mn-incorporated BiVO<inf>4</inf> nanoparticles were investigated by X-ray absorption spectroscopy. XAS results demonstrate that oxidation number of all elements correspond to Mn<sup>2+</sup>/Mn<sup>3+</sup>, Bi<sup>3+</sup>, and V<sup>5+</sup> ions. The normalized Mn K-edge XANES spectra suggest that Mn atoms would not locate at the local site of Bi or V in BiVO<inf>4</inf> crystal because the specific feature of experimental spectra are inconsistent with simulated spectra, which is corresponded to XRD results indicating the formation of Mn-based oxide structures with various oxidation states.
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    Effects of Er Dopant on Structural and Optical Properties of BiVO4 Powders Prepared via Sonochemical Process
    (2022-01-01)
    Noinonmueng, Tanisara
    ;
    Kansaard, Thanophon
    ;
    Wechprasit, Tirapat
    ;
    Mekprasart, Wanichaya
    ;
    Boonyarattanakalin, Kanokthip
    In this work, we investigate the crucial effect of Er dopant on structural, morphological and optical properties of BiVO<inf>4</inf> prepared by one-step sonochemical process. The Er doping content was varied from 0% to 10%. The structural and morphological characterization were performed by X-ray diffraction technique (XRD), Raman spectroscopy and scanning electron microscopy. XRD and Raman spectra reveal the structural transition from monoclinic to tetragonal structure induced by Er dopant. Optical properties of the prepared samples were investigated by diffuse reflectance technique and the corresponding optical band gaps were calculated indicating two optical band gaps of two major phases of the doped samples. The Er dopant has highly influence on an enhancement in photocatalytic performance under visible irradiation of BiVO<inf>4</inf> as doping content is 8%. This improved performance could be due to the size reduction and morphological change due to phase transformation induced by Er dopant accompanying mixture of optical band gaps that can assist the retardment of electron-hole pair recombination.