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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
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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+/h+ 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>.
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Structural studies and photocatalytic properties of Mn and Zn co-doping on TiO2 prepared by single step sonochemical method
(2020-06-01)
Wattanawikkam, Chakkaphan
;
Pecharapa, Wisanu
Titanium dioxide nanoparticles dual doped with zinc and manganese were prepared by the single step of sonochemical method using the sonicator with 20 kHz and 750 W for 30 min. Phase structure analysis results showed that the pure anatase phase was detected for all prepared samples. TEM analysis reveals the nanosized structure with uniformity of nanoparticles. The calculated bandgap energies change to be below the typical band gap energy of bare TiO<inf>2</inf> and single doped sample suggesting high ability to harvest visible light. X-ray absorption spectroscopy was conducted to investigate the electronics structure and to study the local structure of prepared samples. XANES results confirmed the existence of Ti4+ ions in all prepared samples with anatase crystal structure. EXAFS analysis indicates the Ti4+ site was substituted by Mn and Zn dopant ions. The photocatalytic performance was evaluated by degradation of Rhodamine B dye solution under visible light irradiation. The results revealed that the dually Mn–Zn doped TiO<inf>2</inf> sample exhibited excellent photocatalytic activity comparing to single doped and pure TiO<inf>2</inf>. The complete degradation of dye was achieved at optimum condition of 1 mol%-Zn and 2 mol%-Mn molar ratio. The highest photodegradation rate constant was found to be 0.0238 min−1, which is 10 times greater than pure-TiO<inf>2</inf> samples.
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X-ray absorption spectroscopy analysis and photocatalytic behavior of ZnTiO3 nanoparticles doped with Co and Mn synthesized by sonochemical method
(2019-04-30)
Wattanawikkam, Chakkaphan
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Kansa-ard, Thanaphon
;
Pecharapa, Wisanu
ZnTiO<inf>3</inf> (ZTO) as a perovskite structure doped with Co and Mn were fabricated by sonochemical process. Structural phase, chemical and local atomic structure and photocatalytic activity of the synthesized samples were characterized, by X-ray diffraction, by X-ray absorption spectroscopy and Rhodamine B (RhB) dye degradation. The XRD results revealed that the mixing phases of cubic and hexagonal zinc titanate phases were found in all samples. The X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure technique (EXAFS) have been used to identify the crystal and atomic local structure of prepared samples. The Fourier transform EXAFS results of these prepared samples agreed well with the model of Co and Mn substituting at the B-site of ABO<inf>3</inf> structure together with small cluster of CoO and Mn<inf>2</inf>O<inf>3</inf> cluster. The photocatalytic activity for rhodamine b dye degradation under visible light irradiation exhibited that the doped samples had the superior degradation compared to bare-ZTO sample. The results suggest that the incorporation of transition metal ions of Co and Mn dopants is an effective way to improve the catalytic efficiency of perovskite ZTO structure. The effect of different dopant ions and dopant concentration on the structural, chemical, optical and photocatalytic activity are discussed.
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Synthesis of nanocrystalline cobalt ferrite by the sonochemical method in highly basic aqueous solution
(2017-01-01)
Pasupong, Patchara
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Choojun, Kittisak
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Vittayakorn, Naratip
;
Seeharaj, Panpailin
This study reported the preparation of nanocrystalline CoFe2O4 in single step by the sonochemical method in highly basic aqueous solution without requiring of high temperature calcination process. To prepare nanocrystalline CoFe2O4, the mixed solution of the required molar ratio of cobalt nitrate hexahydrate (Co(NO<inf>3</inf>).6H2O) and ferric nitrate nonahydrate (Fe(NO<inf>3</inf>).9H2O) was precipitated in high concentration of sodium hydroxide medium solution (NaOH) under high intensity ultrasonic irradiation (20 kHz, 150 W/cm2). The effect of NaOH concentration (5, 10, 15 and 20 M) on phase formation, microstructure and magnetic property of CoFe2O4 was investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) results showed that the as-prepared powders were single phase CoFe2O4 with cubic spinel structure. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study showed that nanocrystalline CoFe2O4 had monosized distorted spherical morphology and an agglomeration of the nanocrystalline CoFe2O4 into nanoparticles was observed when increasing the NaOH concentration. The nanocrystalline CoFe2O4 exhibited superparamagnetic property and the saturation magnetization (Ms) obtained from vibrating sample magnetometry (VSM) was found to correlate with the crystallite size and varied from 39-45 emu/g.
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The effect of zirconium on the perovskite phase formation of barium zirconium titanate nanoparticles by the sonochemical method
(2016-01-26)
Wirunchit, Supamas
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Baitahe, Rattanai
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Vittayakorn, Wanwilai
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Vittayakorn, Naratip
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Maensiri, Santi
The sonochemical technique is a powerful synthetic method for the production of nanostructured inorganic powders. Monosized spherical barium zirconium titanate [Ba(Zr<inf>x</inf>Ti<inf>1-</inf><inf>x</inf>)O<inf>3</inf>; BZT], with x = 0.00, 0.05, 0.20 and 0.40 nanoparticles, were synthesized successfully through sonochemical reaction. The phase formation as well as crystal structure and morphology were investigated. The as-prepared powders were identified by X-ray diffraction (XRD). The cubic perovskite structure of BZT was formed completely in a short irradiation time without the calcination process. The lattice parameter (a) of the samples increased with increasing zirconium concentration. Furthermore, when the concentration of zirconium increased, the reaction time must be increased in order to obtain phase-pure perovskite. The BZT nanoparticles showed a monosized spherical shape that was different from that in other preparation methods. The morphology of the products was very close to spherical, with the particle size distribution being rather narrow.
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Sonochemical synthesis of monodispersed perovskite barium zirconate (BaZrO3) by using an ethanol-water mixed solvent
(2015-07-01)
Charoonsuk, Thitirat
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Vittayakorn, Wanwilai
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Vittayakorn, Naratip
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Seeharaj, Panpailin
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Maensiri, Santi
Perovskite barium zirconate (BaZrO<inf>3</inf>) was synthesized successfully in an ethanol-water mixed solvent under ultrasonic irradiation. Four compositions, including 0%, 30%, 50%, and 70% by volume of ethanol in ethanol/water mixed solvent, were used. The effect of ethanol content and irradiation time on the phase formation and morphology of product particles was studied and discussed. As a result, a pure perovskite BaZrO<inf>3</inf> phase was formed completely at a short irradiation time of about 15 min in 70% by volume of ethanol without the calcination process. The average particles size decreases and particle size distribution becomes narrower by increasing the percentage of ethanol volume. On the other hand, the monodispersibility of BaZrO<inf>3</inf> particles was improved significantly through ultrasonic irradiation.
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Al-doped ZnO nanoparticles synthesized by sonochemical-assisted method
(2013-10-08)
Chongsri, K.
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Wongpisutpaisan, N.
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Sungthong, A.
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Vittayakorn, N.
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Pecharapa, W.
Al-doped ZnO nanoparticles were synthesized by sonochemical method from zinc acetate dehydrate and aluminum acetate as starting precursors. The deionized (DI) water was selected as the solvent. Sonication of the precursor was performed by a Sonics Model VCX 750 for 30 minutes until precipitated product was finally obtained. The as-precipitated powders were calcined at different temperature range of 550-1100 °C for 2 hr. For all samples, their crystal structures were investigated by X-ray diffraction (XRD) and surface morphologies were observed by scanning electron microscope (SEM). The XRD results revealed that, the purity of as-synthesized powders increases when the calcination temperature increases. Moreover, it is noticed that the AlZnO partial peaks will appear when the as-synthesized powders were calcined at 800 - 1000 °C. In addition, SEM micrographs show the increase of agglomeration and the particles when the calcination temperature increases. © (2013) Trans Tech Publications, Switzerland.

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