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Synergistic effects of biomass-derived carbon quantum dots and Cu Co-doping on TiO2 nanocomposite for enhanced visible-light photocatalysis
(2026-12-01)
Zhao, Huali
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Noonuruk, Russameeruk
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Bootchanont, Atipong
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Porjai, Porramain
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Thongpool, Voranuch
The development of sustainable approaches for enhancing the visible-light activity of TiO<inf>2</inf>-based photocatalysts has attracted considerable research interest. In this work, carbon quantum dots (CQDs)-Cu co-modified TiO<inf>2</inf> nanocomposites were synthesized via a hydrothermal method using butterfly pea ( Clitoria ternatea ) flowers as a biomass-derived carbon source. The Cu content was fixed at 1.5 mol% relative to Ti, while the CQDs loading was controlled by varying the butterfly pea precursor concentration from 0.25 to 1.25 g L−1, yielding 1C–Cu–TiO<inf>2</inf>, 3C–Cu–TiO<inf>2</inf>, and 5C–Cu–TiO<inf>2</inf> samples. The prepared materials were characterized by electron microscopy, X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, photoluminescence (PL), and X-ray absorption spectroscopy (XAS). High-resolution transmission electron microscopy revealed CQDs with an average size of approximately 4.29 nm and an interplanar spacing of approximately 0.23 nm. All composites retained the anatase TiO<inf>2</inf> phase after Cu incorporation and CQDs modification. Enhanced visible-light absorption was observed and is attributed to the formation of Cu-related sub-band-gap states and the sensitization effect of CQDs. PL analysis showed an emission peak at ∼415 nm under 660 nm excitation, suggesting the presence of upconversion photoluminescence behavior in the CQDs. Conventional PL spectra further suggested reduced charge-carrier recombination in the modified composites. Photocatalytic activity was evaluated through Rhodamine B (RhB) degradation under visible-light irradiation. Among all samples, 1C–Cu–TiO<inf>2</inf> exhibited the highest performance, achieving degradation efficiency of 99.28% within 50 min. The apparent reaction rate constant reached 0.1038 min−1, which was 2.23, 1.96, and 2.90 times higher than those of pristine TiO<inf>2</inf>, Cu–TiO<inf>2</inf>, and 3C–Cu–TiO<inf>2</inf>, respectively. Radical scavenging experiments indicated that •OH and h+ were the dominant reactive species, while •O<inf>2</inf>− also participated in the degradation process. The enhanced photocatalytic performance is attributed to the synergistic effects of Cu and biomass-derived CQDs in improving visible-light harvesting and charge separation, providing an effective approach for developing visible-light-responsive TiO<inf>2</inf> photocatalysts.
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Characterization and x-ray absorption spectroscopy of ilmenite nanoparticles derived from natural ilmenite ore via acidassisted mechanical ball-milling process
(2017-09-01)
Phoohinkong, Weerachon
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Pavasupree, Sorapong
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Wannagon, Anucha
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Sanguanpak, Samunya
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Boonyarattanakalin, Kanokthip
In this work activated ilmenite nanoparticles were prepared by chemical-assisted in mechanical ball-milling process from ilmenite ore as starting raw material. The effect of milling process on their phase composition, particle size, surface morphology and local structure were investigated. Phase identification and crystalline structure of ilmenite mineral, milled samples and subsequent leached residues were characterized by x-ray diffraction (XRD). Meanwhile, the distorted octahedral structure and the oxidation state of relevant elements in ilmenite ore and activated ilmenite obtained by different process conditions were analyzed by x-ray absorption spectroscopy (XAS). Particle size and morphologies of the samples were monitored by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). Three dominant peaks of TiO2 rutile, FeTiO<inf>3</inf>, and Fe<inf>2</inf>TiO<inf>4</inf> are obviously adulterated in XRD patterns after mechanical milling with water and acid solution when comparing to precursor mineral. However, the contaminated phase of FeTiO3 and Fe<inf>2</inf>TiO<inf>4</inf> was readily decreased by acid-assisted mechanical ball-milling. The enhancement in leaching process of ilmenite residue after milling can be obtained with sulfuric acid. This result suggests that iron contaminated phase could be leached from the sample resulting to the decrease in Fe environment around Ti atom.
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X-ray absorption spectroscopy analysis and magnetic properties of M-doped TiO2 nanoparticles (M=Co, Mn, Ni and Zn) prepared by co-precipitation method
(2017-08-01)
Wattanawikkam, Chakkaphan
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Pecharapa, Wisanu
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Ishihara, Keiichi N.
M-doped TiO<inf>2</inf> nanoparticles (M=Co, Mn, Ni and Zn) were synthesized by co-precipitation method combined with annealing at 500 °C for 2 h. X-ray diffraction (XRD) was used to identify their structural phases. X-ray absorption near edge structure (XANES) was conducted to probe the chemical state and crystal atomic structure of prepared samples. Magnetic properties of all samples were characterized by vibrating sample magnetrometer (VSM). The XRD analyses reveal that all samples crystallize in anatase tetragonal structure with no additional peaks. The XANES spectra exhibit triple pre-edge fingerprint of Ti4+ of oxidation state with six-fold octahedral coordinate structure. Co-, Ni- and Zn- K-edge results indicate that the Co, Ni and Zn ions in M-doped TiO<inf>2</inf> are in 2+ formal oxidation state. Meanwhile, Mn-doped TiO<inf>2</inf> sample contains the different oxidation states of 3+ and 4+. The amount of each oxidation state is confirmed by using linear combination fitting method. The magnetic measurement illustrates the paramagnetic behavior for Co-, Mn- and Ni- doped samples that strongly depend on the doping content and no hysteresis loop is observed in undoped and Zn-doped samples.
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Effect of calcination temperature on structure and photocatalytic activity under UV and visible light of nanosheets from low-cost magnetic leucoxene mineral
(2017-07-01)
Charerntanom, Wissanu
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Pecharapa, Wisanu
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Pavasupree, Suttipan
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Pavasupree, Sorapong
This research has experimentally synthesized the nanosheets from the naturally-mineral magnetic leucoxene under the hydrothermal synthesis condition of 105 °C for 24 h. Magnetic leucoxene was utilized as the starting material due to its high TiO<inf>2</inf> content (70–80%) and inexpensiveness. The characterization of the synthesized nanosheets was subsequently carried out: the crystalline structure, the chemical composition, the shape, the size and the specific surface area, by the X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) specific surface area analysis. The analysis results indicated that the starting magnetic leucoxene is of rutile phase while the synthesized nanosheets are of titanate structure (H<inf>2</inf>Ti<inf>x</inf>O<inf>2x + 1</inf>). After calcination at the temperature range of 300 and 400 °C, the calcined samples demonstrated TiO<inf>2</inf> (B). At 500 and 600 °C, the calcined nanosheets revealed a bi-crystalline mixture consisting of TiO<inf>2</inf> (B) and anatase TiO<inf>2</inf>. At 700–1000 °C, the crystalline structure shows anatase and rutile phase. At 1100 °C, the prepared samples consisted of a mixture of anatase, rutile phase of TiO<inf>2</inf>, and Fe<inf>2</inf>O<inf>3</inf> phase. The synthesized product also exhibited the flower-like morphology with 2–5 μm in diameter, and the nanosheets structure was slightly curved, with 100 nm to 2 μm in width and 1–3 nm in thickness. At 100–200 °C showed sheets-like structure. At 300–1100 °C, the calcined nanosheets became unstable and began to decompose and transform into nanoparticles. The increasing size of nanoparticle decreased the specific surface area of the nanosheets, caused by increasing calcination temperature. Furthermore, the BET specific surface area of the nanosheets was approximately 279.8 m2/g. More importantly, the synthesized nanosheets achieved the higher photocatalytic activity under UV and visible light than did the commercial TiO<inf>2</inf> nanoparticles (JRC-01, JRC-03, ST-01 and P-25).
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Influence of milling time, NH3 additive and annealing temperature on physical properties of modified commercial TiO2 powders via ball milling process
(2014-01-01)
Techitdheera, Wicharn
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Rattanarak, Jiravat
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Mekprasart, Wanichaya
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Pecharapa, Wisanu
N-doped TiO<inf>2</inf> were prepared via ball milling process with different operating times and annealing temperatures. Commercial TiO<inf>2</inf> anatase powders used as TiO<inf>2</inf> precursor were dispersed in ammonia solution for nitrogen source. Ball milled TiO<inf>2</inf> powders at various times were annealed in nitrogen atmosphere at different temperatures. Physical properties and surface morphologies after ball milling process were monitored by X-ray diffraction (XRD) and scanning electron microscope (SEM). The component of samples was characterized by energy-dispersive X-ray spectroscopy (EDX). The active surface area of the samples was investigated by Brunauer Emmet Teller method. SEM result indicated that large particle of TiO<inf>2</inf> precursor could be reduced via ball milling process leading to high active surface area by the increase of milling time. XRD result showed the crystalline structures of TiO<inf>2</inf> after milling process and nitrogen annealing were identical to TiO<inf>2</inf> precursor structure. Meanwhile, the appearance of impurity phase in TiO<inf>2</inf> precursor was also depreciated via ball milling process with ammonia solution and annealing under nitrogen atmosphere.
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Photocatalytic activities under UV light of ball-milled TiO2photocatalysts
(2013-10-29)
Rattanarak, Jiravat
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Mekprasart, Wanichaya
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Pecharapa, Wisanu
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Techitdheera, Wicharn
Anatase TiO<inf>2</inf> powders used as photocatalysts were prepared by ball milling process at various milling time and annealed in nitrogen atmosphereat different temperatures. Commercial TiO<inf>2</inf> powders were ball-milled with ethanol at room temperature. After ball milling process, the samples were annealed in nitrogen atmosphere. The particle sizes and surface area of milled powders were measured by particle analyzer and Brunauer Emmet Teller method(BET). Effect of milling time and annealing temperature on structural properties of TiO<inf>2</inf> powders was investigated by X-ray diffraction(XRD) and scanning electron microscope(SEM). The degradation of aquous RhB dye by ball-milled TiO<inf>2</inf> powder photocatalyst was investigated under UV light irradiation. Comparing to P-25, TiO<inf>2</inf> powder prepared via ball milling process at 24 hr demonstrated significant enhancement in its photocatalytic activity under UV light due to the increasing active surface area after ball milling process. © (2013) Trans Tech Publications, Switzerland.
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Effect of sonication time and calcination temperature on physical properties of titanium dioxide synthesized via sonochemical-assisted process
(2013-10-29)
Kahattha, Chokchai
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Vittayakorn, Naratip
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Pecharapa, Wisanu
Titanium dioxide nanoparticles (TiO<inf>2</inf>) were successfully synthesized via a sonochemical-assisted process using titanium isopropoxide as the titanium sources and calcination process at 300-500 °C. The effect of sonication time and heat treatment temperature on structural and nanostructure properties of the nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM). The XRD and Raman results indicated that the crystalline of as-sonochemically synthesized TiO<inf>2</inf> nanoparticles corresponded to anatase phase of TiO<inf>2</inf> after sonication for 30 mim. The high quality crystalline anatase phase and increasing of crystalline size can be obtained after calcinations process. © (2013) Trans Tech Publications, Switzerland.

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