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Piezoelectric enhanced photocatalytic properties of PVDF–ZnO/Cu nanofibers prepared by electrospinning technique
(2022-01-01)
Bootchanont, Atipong
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Porjai, Porramain
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Noonuruk, Russameeruk
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Wattanawikkam, Chakkaphan
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Pavasupree, Sorapong
Piezoelectric-assisted photocatalysis technology is one of the efficient ways to achieve enhancement in photocatalytic performance by facilitating the separation of photoinduced electron and holes via internal field initiated via piezoelectricity. Herein, bi-piezoelectric integrated effect was generated by the combination of piezoelectric semiconductor photocatalyst ZnO/Cu and piezoelectric polymer polyvinylidene fluoride (PVDF). Firstly, ZnO/Cu nanoparticles were prepared by facile co-precipitation method. Then, nanoparticles (at 10–30 wt%) were loaded in PVDF for fabricating nanofibers by electrospinning technique. All PVDF–ZnO/Cu nanofibers were characterized by XRD, FE-SEM, FTIR, XAS, and UV–Vis DRS. The structural study indicates that the β- and α-phase PVDF is observed in all the prepared nanofibers. XANES technique confirms the oxidation state of 2+ for Zn and Cu ions in both nanoparticles and nanofibers. Furthermore, under the synergy action of ultrasonic and visible light irradiation, PVDF–ZnO/Cu nanofibers exhibit superior piezo-photocatalytic degradation of rhodamine B dye when compared with single light or mechanical excitation. Effects of ZnO/Cu concentration on optical, piezoelectric, and photocatalytic properties are discussed.
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Solvent-Free Hydrodeoxygenation of Triglycerides to Diesel-like Hydrocarbons over Pt-Decorated MoO2Catalysts
(2020-03-31)
Fangkoch, Sisira
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Boonkum, Sutida
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Ratchahat, Sakhon
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Koo-Amornpattana, Wanida
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Eiad-Ua, Apiluck
In the present work, the solvent-free hydrodeoxygenation of palm oil as a representative triglyceride model compound to diesel-like hydrocarbons was evaluated in a batch reactor using Pt-decorated MoO2 catalysts. The catalysts with various Pt loadings (0.5-3%) were synthesized by an incipient wetness impregnation method. The metallic Pt and MoO2 phases were detected in the XRD patterns of as-prepared catalysts after the reaction and acted as active components for the deoxygenation reactions. The XPS experiments confirmed the existence of metallic Pt and PtOx species. The XANES investigation of Mo L3-edge spectra elucidated a change in the valence state by the transformation of MoO3 into MoO2 species after the deoxygenation reaction. The TEM observation revealed the formation of Pt nanoparticles in the range of 1-3 nm decorated on MoO2 species. The number of acid sites increased with stronger metal-support interactions on increasing the Pt loading. The catalytic performance of the MoO2 catalyst significantly improved with a small amount of Pt decoration. However, the further increase in Pt loading did not relatively increase the deoxygenation activity due to the formation of the agglomerated Pt particles. The high performance of the decorated catalysts could be attributed to the moderate acidity from the Pt dispersed on MoO2 toward decarbonylation and decarboxylation reactions.
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The disordered cation distribution studies of nanosized zinc ferrite powders by synchrotron X-ray absorption spectroscopy
(2016-04-26)
Tangcharoen, Thanit
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Klysubun, Wantana
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Kongmark, Chanapa
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Pecharapa, Wisanu
The non-equilibrium site occupancy of zinc (Zn2+) and ferric (Fe3+) ions in dissimilar nanosized zinc ferrites (ZnFe2O4)powders obtained from the different milling time (0 to 24 h) of the as-combusted powders was investigated through Zn and Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. Compared with the bulk specimen of zinc ferrite, both XANES and EXAFS spectra of nanosized zinc ferrite powders clearly exhibit the large Zn2+ ions translocation from the tetrahedral (A) sites to the octahedral (B) sites leading to the movement of many Fe3+ ions in the opposite direction without the variation in the long-range structural order.
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Effect of Annealing Time on the Cation Distribution in Mn Doped CoFe2O4
(2016-02-19)
Roongtao, Rachanusorn
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Vittayakorn, Naratip
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Klysubun, Wantana
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Vittayakorn, Wanwilai C.
In this work, the series of CoFe<inf>2</inf><inf>x</inf>Mn<inf>x</inf>O<inf>4</inf> powders were synthesized using the solid state method. The structure and lattice parameter of the samples were determined by the X-ray diffraction (XRD) and Rietveld refinement method. The morphology was confirmed without annealing and with annealing at 500°C for 4 and 100 h, with the samples examined by scanning electron microscopy (SEM). Then, the distribution of migrating cations was analyzed using X-ray absorption spectroscopy (XAS). Also, magnetic properties were examined by a vibrating sample magnetometer (VSM). It can be confirmed from the morphology that the average particle size before and after annealing remained unchanged, and ranged from 0.66 ± 0.20 m to 0.79 ± 0.26 m. Furthermore, the distribution of cations was no different after annealing Mn ions at 500°C for 100 h. However, the distribution of cations migrated to their site of preference after annealing Co and Fe ions in the structure. The result of migrations induced a saturated magnetization increase to 42.24 emu/g.
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Synchrotron X-ray absorption spectroscopy study of disordered cation distribution of nanosized zinc ferrite powders
(2016-01-01)
Tangcharoen, Thanit
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Kongmark, Chanapa
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Klysubun, Wantana
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Pecharapa, Wisanu
The zinc ferrite (ZnFe<inf>2</inf>O<inf>4</inf>) powders of various nanoparticle sizes were synthesised at different milling times (0 to 24 h) of the as-combusted powders. The non-equilibrium site occupancy of zinc (Zn2+) and ferric (Fe3+) ions was investigated through Zn and Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. The XRD and SEM strongly confirm the particle size of these ferrites decreasing with the increasing milling time. Compared with the bulk specimen of zinc ferrite, both XANES and EXAFS spectra of zinc ferrite powders clearly exhibit the large translocation of Zn2+ ions from the tetrahedral (A) sites to the octahedral (B) sites and the opposite translocation of some of Fe3+ ions without affecting the long-range structural order. Moreover, the curve-fitting analysis of Zn and Fe K-edge EXAFS spectra indicates that the degree of inversion increases as the particle size decreases resulting in significant differences in the magnetic behaviours.
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A comparison of cation distribution and valence state in spinel crystal structure of zinc and nickel ferrites using the synchrotron X-ray absorption spectroscopy (XAS) analysis
(2014-07-24)
Tangcharoen, Thanit
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Klysubun, Wantana
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Ruangphanit, Anucha
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Pecharapa, Wisanu
In this work, the physical structure, magnetism and local structure of zinc and nickel ferrites (ZnFe<inf>2</inf>O<inf>4</inf> and NiFe<inf>2</inf>O <inf>4</inf>) synthesized by typical sol-gel combustion method, were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The formation of the single phase cubic spinel crystal structure and the different values of crystallite size (D), interplanar distance (d) and lattice constant (a) for all ferrite samples were evaluated by the XRD data. The VSM measurement provides the characteristic magnetic hysteresis loop (M-H) for each sample which was found to be significantly different from each other. The chemical shifts in Zn, Ni and Fe K-edges XANES spectra indicate the existence of Zn2+, Ni2+ and Fe3+ ions in these ferrites. The EXAFS spectra analyses applied to track Zn, Ni and Fe cation distribution indicate the distinct character of spinel crystal structure of both ferrites. The results exhibit that zinc ferrite is a normal spinel, while the nickel ferrite is an inverse spinel. Moreover, these EXAFS spectra analyses reveal that the distances between metal ion (Zn2+ or Ni2+) to central oxygen ion and to Fe3+ ions in the opposite lattice site for each ferrite sample are unequal which highly affect its magnetism. The overall simulated results are one of the important evidence encouraging the explanation on the paramagnetism for ZnFe<inf>2</inf>O<inf>4</inf> and the ferrimagnetism for NiFe<inf>2</inf>O<inf>4</inf>. © 2014 Taylor & Francis Group, LLC.
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Synchrotron X-ray absorption spectroscopy and magnetic characteristics studies of metal ferrites (metal = Ni, Mn, Cu) synthesized by sol-gel auto-combustion method
(2014-01-01)
Tangcharoen, Thanit
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Klysubun, Wantana
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Kongmark, Chanapa
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Pecharapa, Wisanu
In this work, the metal ferrites MFe<inf>2</inf>O<inf>4</inf> (M = Ni, Mn, Cu) were synthesized from metal nitrate precursors by the sol-gel auto-combustion method using diethanolamine (DEA) as a potential fuel. The crystal structures of these ferrite powders were characterized by X-ray diffraction (XRD) technique confirming the complete formation of the single-phase cubic spinel crystal structure. The ferrimagnetism characteristic and the difference of the magnetic properties such as saturation magnetization (M<inf>s</inf>), remanent magnetization (M<inf>r</inf>), and coercivity (H <inf>c</inf>) for each after-calcined ferrite sample were scrutinized through the ferrimagnetic hysteresis loop (M-H) obtained from the vibrating sample magnetometer (VSM) measurement. Moreover, the cation distribution and valence state of these ferrites were investigated by the Ni, Mn, Cu, and Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra using the synchrotron radiation light source. From the XAS results, the analyses of both XANES and EXAFS spectra show the existence of accurate oxidation state for transition metal ions and the interionic distance to the nearest neighbors in the spinel crystal structure. In particular, the curve-fitting analysis of Ni, Mn, Cu, and Fe K-edge EXAFS spectra indicates that the degree of inversion in these metal ferrites is entirely different and found to be 0.2 for MnFe<inf>2</inf>O<inf>4</inf>, 0.8 for CuFe<inf>2</inf>O <inf>4</inf>, and 1.0 for NiFe<inf>2</inf>O<inf>4</inf>, which are the important information for understanding their effects on relevant magnetic properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Structural and magnetic properties of Zn doped CoFe2O 4
(2013-12-01)
Roongtao, Rachanusorn
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Baitahe, Rattanai
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Vittayakorn, Naratip
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Klysubun, Wantana
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Vittayakorn, Wanwilai C.
Zinc doped cobalt ferrite powders were prepared by the solid state reaction method. The effect of zinc substitution on structure, morphology and magnetic properties was investigated. The X-ray analysis confirmed existence of the single phase cubic spinel structure, while Rietveld refinement data showed increasing of lattice parameters with zinc content. In addition, saturated magnetization increased with increasing zinc concentration and it was contained at maximum in CoFe<inf>1.9</inf>Zn0.<inf>1</inf>O<inf>4</inf> powders. However, the value of coercivity was decreased with zinc doped content. Furthermore, the oxidative states were characterized by X-ray absorption spectroscopy. The results confirm that the structure contained Co2+, Fe3+ and Zn2+ ions. © 2013 Copyright Taylor and Francis Group, LLC.
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Sol-gel combustion synthesis and characterizations of nanocrystalline Zinc, Nickel and Nickel-Zinc ferrites
(2013-10-29)
Tangcharoen, Thanit
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Ruangphanit, Anucha
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Klysubun, Wantana
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Pecharapa, Wisanu
In this work, X-ray diffraction (XRD), Raman spectroscopy (RAMAN) and vibrating sample magnetometer (VSM) measurements were employed to investigate the crystal structure, chemical bonding and magnetic properties of the nanocrystalline Zinc, Nickel and Nickel-Zinc ferrites (ZnFe<inf>2</inf>O<inf>4</inf>, NiFe<inf>2</inf>O<inf>4</inf> and Ni<inf>0.5</inf>Zn<inf>0.5</inf>Fe<inf>2</inf>O<inf>4</inf>) which were synthesized by sol-gel combustion method. Moreover, the composition of elements and the electronic structure including the cation distribution for all ferrite samples were examined through synchrotron X-ray fluorescence (XRF) and X-ray absorption near-edge structure (XANES) spectra. The overall characterization results indicate that the different amount of zinc and nickel ions in ferrites has crucial effect on their physical, magnetism and the site occupancy distribution of Fe3+ ions. © (2013) Trans Tech Publications, Switzerland.
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Characterization and enhanced photocatalytic performance of nanocrystalline Ni-substituted Zn ferrites synthesized by DEA-assisted sol-gel auto-combustion method
(2013-06-01)
Tangcharoen, Thanit
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Ruangphanit, Anucha
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Klysubun, Wantana
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Pecharapa, Wisanu
Nanocrystalline Ni-substituted Zn ferrites with compositions of Ni <inf>x</inf>Zn<inf>1-x</inf>Fe<inf>2</inf>O<inf>4</inf> (x = 0-1.0) were synthesized by sol-gel auto-combustion method using metal nitrate as the reactants. Diethanolamine was selected as the fuel instead of conventional fuels such as urea, citric acid, tartaric acid or glycine. Characterization of after-calcined ferrite samples were conducted in terms of crystal structure, molecular vibrations, morphology and magnetic properties through X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope and vibrating sample magnetometer analysis, respectively. The photocatalytic activities of these ferrites were studied in term of degradation of Rhodamine B under daylight-irradiation. The corresponding results indicate that nickel loading content has significant effect on physical, magnetic, optical and photocatalytic properties of the ferrite. Comparing to the undoped Zn ferrite, Ni<inf>0.6</inf>Zn<inf>0.4</inf>Fe<inf>2</inf>O<inf>4</inf> shows the enhancement in photocatalytic activity accompanying the degradation of Rhodamine B aqueous solution up to 77 % within 4 h. The result suggests the feasibility of this material as potential sunlight-activated photocatalyst in wastewater treatment and environment cleaning applications. © 2013 Springer Science+Business Media New York.

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