KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Settings

Author: search.filters.author.Pavasupree, SorapongSubject: search.filters.subject.XANES

Search Results

Now showing 1 - 3 of 3
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Characterization, X-ray absorption spectroscopic analysis and photocatalytic activity of Co/Zn co-doped TiO2 nanoparticles synthesized by one-step sonochemical process
    (2021-10-01)
    Mekprasart, Wanichaya
    ;
    Pavasupree, Sorapong
    ;
    Jayasankar, C. K.
    ;
    Ravuri, Balaji Rao
    ;
    Wattanawikkam, Chakkaphan
    A novel one-step preparation of sonochemical method was applied to synthesize Co/Zn co-doped TiO<inf>2</inf> nanoparticles using a sonicator of 750 W, 20 kHz for 30 min at room temperature. The formation of the anatase TiO<inf>2</inf> phase for all as-prepared samples was observed from XRD results with a crystalline size in nanoscale. The use of ultrasound allowed for the successful doping of both Co and Zn into the TiO<inf>2</inf> lattice, which was confirmed by Synchrotron light including X-ray near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS) spectroscopy. Ti K-edge, Co K-edge, and Zn K-edge XANES spectra exhibited the dominating +4, +2, and +2 valence state of Ti, Co, and Zn in as-prepared samples, respectively. A detailed XANES and EXAFS data analysis give strong evidence that the Co/Zn dopants partially replace the Ti atom of the TiO<inf>2</inf> host. The Co/Zn co-doping extends the light absorption of the host to the visible region and restricts the e<sup>+</sup>/h<sup>+</sup> recombination. The photocatalytic activity of samples was tested for degradation of Rhodamine B dye solution under visible light irradiation. The as-synthesized of the co-doped catalyst was presented as highly efficient, with 2.5 and 5 times dye degradation compared with single-doped and bare TiO<inf>2</inf>.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Nonlocal XANES pre-edge feature of FeTiO3 ilmenite-type at Ti and Fe K-edge
    (2020-09-01)
    Phoohinkong, Weerachon
    ;
    Boonyarattanakalin, Kanokthip
    ;
    Mekprasart, Wanichaya
    ;
    Pavasupree, Sorapong
    ;
    Pecharapa, Wisanu
    The pre-K-edge feature of Ti and Fe XANES of ilmenite FeTiO<inf>3</inf> were investigated. The electronic structure of FeTiO<inf>3</inf> was examined based on the partial density of electronic state distribution on both local and nonlocal atoms. A strong contribution of nonlocal metal-metal intervalence electronic states of Ti and Fe pre-K-edge was observed in X-ray absorption near-edge structure (XANES) measurement. This observation agrees well with the calculated local state density. The nonlocal excitation transitions in the pre-edge feature contribute to local pre-K-edge at both Ti and Fe. Ti pre-K-edge consists of highly hybridized Ti-3d(t<inf>2g</inf>) with a small part of dipole-allowed 4p and a small 4s density transition state feature which is predominated by nonlocal of Fe-3d mixed with 4p state delocalized via O-2p as the main component peak. The peak feature at Ti-3d(e<inf>g</inf>) energy state is assigned to hybridization of Ti-3d(e<inf>g</inf>) and Ti-4p state contributed with nonlocal of the hybridized Fe-sp and the Ti-pd state. Fe pre-K-edge shows two main prominent transition peaks of hybridized Fe-pd state and the delocalized local Fe-sp with nonlocal Ti-3d(t<inf>2g</inf>) and 4p mixing states centered at 7112.38 and 7116.48 eV, respectively. The local and nonlocal excited transition energy states and density of both Ti pre-K-edge and Fe pre-K-edge features are corresponded with each other through the O-2p state transition pathway.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    ACTIVE-ILMENITE SURFACE STRUCTURE INFLUENCE ON ACID-ASSISTED BALL MILLING
    (2018-12-01)
    Phoohinkong, Weerachon
    ;
    Pavasupree, Sorapong
    ;
    Boonyarattanakalin, Kanokthip
    ;
    Mekprasart, Wanichaya
    ;
    Pecharapa, Wisanu
    Active-ilmenite powder derived from natural ilmenite sand was prepared by the ball milling process with acid-solution and Deionized (DI) water. Morphology and particle size of active-ilmenite product in acid/DI-assisted ball milling process were monitored by field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). Surface atomic component and chemical bonding were investigated by X-ray photoelectron spectroscopy (XPS). Meanwhile, bulk chemical oxidation and fine structure of active-ilmenite were studied by X-ray absorption near edge structure (XANES) and extended X-ray absorption ne-structure spectroscopy (EXAFS) to confirm the oxidation state and local active species structure at surface. Active-ilmenite by acid-assisted ball milling process is a distinctive method for the preparation of active-ilmenite product with high active surface. Moreover, the distortion of TiO <inf>6</inf> and FeO <inf>6</inf> octahedral cluster on the sample surface was detected in all milled samples with acid-assisted ball milling process. The presence of Fe <sup>2+</sup> , Fe <sup>3+</sup> ions and miniature sulfate was also detected on the sample surface by milled product with acid-assisted method.