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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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Plant assisted synthesis of CuO/ZnO heterojunction nanocomposites using Mitragyna speciosa (Korth.) Havil leaf extract for photocatalytic activity under full spectrum LED light and antibacterial performance
(2026-07-15)
Phunpueok, Akapong
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Thongpool, Voranuch
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Jaiyen, Sarawut
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Bootchanont, Atipong
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Sukprasit, Nuchita
CuO/ZnO heterojunction nanocomposites were synthesized through a green plant assisted method using Mitragyna speciosa leaf extract as a natural reducing and stabilizing agent. Structural and morphological analyses (XRD, FE-SEM, EDS, UV–vis, and BET) confirmed the formation of CuO/ZnO heterostructures with mesoporous characteristics. The 0.25CuO/0.75ZnO heterojunction nanocomposites exhibited the smallest ZnO crystallite size (∼8.06 nm) and the highest surface area (28.97 m2/g). Photocatalytic performance evaluated by methylene blue degradation under full-spectrum irradiation showed that the 0.25CuO/0.75ZnO heterojunction nanocomposites achieved 92.29% degradation within 90 min with a rate constant of 0.02491 min−1. In addition, the nanocomposites demonstrated strong antibacterial activity, achieving 99.9% reduction of E. coli and >99.9% inhibition of S. aureus . The enhanced performance is attributed to efficient charge separation at the CuO/ZnO heterojunction and the generation of reactive oxygen species.
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Sphere-like and flake-like ZnO immobilized on pineapple leaf fibers as easy-to-recover photocatalyst for the degradation of congo red
(2021-04-01)
Deebansok, Siraprapha
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Amornsakchai, Taweechai
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Sae-Ear, Pannagorn
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Siriphannon, Punnama
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Smith, Siwaporn Meejoo
This work reports immobilization of ZnO photocatalyst on very fine pineapple leaf fiber (PALFs) by a by polyelectrolyte coating method, for the removal of colored pollutants from water stream, allowing for simple recovery after use. It also emphasizes on the effect of defect structure containing in ZnO of hierarchical sphere-like and flake-like morphologies on the color removal performance. The photocatalytic activity of ZnO/PALFs for degradation of congo red (CR) dye was examined under static (dark) and UV/visible irradiation conditions, and effective color removal (>95 %) was achieved, as the results of adsorption and photo-oxidation processes. Results from photoluminescence and X-ray photoelectron spectroscopy suggested that the sphere-like ZnO, bearing zinc vacancies (VZn), zinc interstitials (Zni), singly ionized oxygen vacancies (Vo+), and oxygen vacancies (Vo), has superior photocatalytic activity up to 3.6 times compared to that of flake-like ZnO. With the recyclability up to 3 cycles (>84 % color removal efficiencies), the ZnO immobilized on PALFs have shown a great promise as an easy-to-recover photocatalyst for the removal of colored pollutants in wastewater treatment processes.
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Removal of methylene blue dye using metal-free g-C3N4 photocatalyst over natural sunlight irradiation
(2020-01-01)
Sriwong, Chaval
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Choojun, Kittisak
This work presented the high activity of metal-free g-C<inf>3</inf>N<inf>4</inf> photocatalyst for methylene blue (MB) removing over natural sunlight irradiation. These g-C<inf>3</inf>N<inf>4</inf> photocatalysts materials were synthesized by a conventional thermal condensation method using melamine as a precursor under treated at the various annealing temperatures (450 °C, 500 °C, 550 °C, 600 °C and 650 °C). All assynthesized samples were characterized and confirmed by a several techniques, such as, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectrometer (DRS), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) specific surface area. XRD and FTIR results confirmed that the as-synthesized g-C<inf>3</inf>N<inf>4</inf> samples were completely synthesized at annealing temperature of 500 °C. SEM images showed the morphologies of the g-C<inf>3</inf>N<inf>4</inf> samples had more flake-like structures upon the increasing of annealing temperatures. WhileDRS results indicated that the absorption edges of as-synthesized g-C<inf>3</inf>N<inf>4</inf> samples were shifted to visible-light region, except the sample as-synthesized at 650 °C (g-C<inf>3</inf>N<inf>4</inf>-650 °C). Moreover, the photocatalytic properties of metalfree g-C<inf>3</inf>N<inf>4</inf> photocatalyst materials were evaluated by degrading of MB dye solution under natural sunlight irradiation for 100 min. The results revealed that the highest photocatalytic activity was exhibited by the sample synthesized at 600 °C, which the apparent rate constant (kapp.) was 0.0291min-1. The orders of activities as:g-C<inf>3</inf>N<inf>4</inf>-600°C > g-C<inf>3</inf>N<inf>4</inf>-650 °C > g-C<inf>3</inf>N<inf>4</inf>-550 °C > g-C<inf>3</inf>N<inf>4</inf>-500°C > g-C<inf>3</inf>N<inf>4</inf>-450°C. Hence, the metal-free g-C<inf>3</inf>N<inf>4</inf> photocatalyst appears to be an attractivematerial for water or wastewater purification applications over activated by sunlight irradiation.
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Factors affecting the degradation of linear alkylbenzene sulfonate by TiO2 assisted photocatalysis and its kinetics
(2018-01-01)
Jariyanorasade, Anon
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Junyapoon, Suwannee
This research aims to study photocatalytic degradation of linear alkylbenzene sulfonate (LAS) in synthetic solution and industrial laundry wastewater by UV/TiO<inf>2</inf> process. The structural and surface properties of Degussa P25 TiO<inf>2</inf> powder were measured by X-ray diffractometer (XRD) and Autosorb, respectively. Factors affecting the photocatalytic decomposition i.e. pH, TiO<inf>2</inf> dosage, irradiation time, initial LAS concentration were investigated in a batch reactor. The kinetic of LAS degradation was studied at room temperature. After degradation, byproduct formation was analyzed using GC-MS. The experimental results showed that a dominating crystalline structure of TiO<inf>2</inf> was the tetragonal anatase phase (82.58%). The TiO<inf>2</inf> had a surface area of 77.79 m2/g, a pore size of 14.38 nm in diameter and a pore volume of 0.28 cc/g. It was found that the optimum conditions for photocatalytic degradation of LAS were at initial LAS concentration of 20 mg/L, non-adjust pH (pH 5.5), TiO<inf>2</inf> dosage of 100 mg/L with irradiation time for 60 mins. Under these conditions, the removal efficiency of LAS in the synthetic solution reached 83.20%. The removal of LAS follows the second order kinetic with rate constant of 0.0031 L/mg/min and half-life of 16.13 min. Alkyl long chains, carboxylic acids and aromatic rings were detected as its degradation products. The removal efficiencies of LAS, orthophosphates and COD in industrial laundry wastewater were 51.99±7.36%, 45.98±4.85 % and 16.00±0.00%, respectively.
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Characterization and photocatalytic activity of titanium dioxide deposited on stainless steel by pulsed-pressure MOCVD
(2018-01-01)
Wirandorn, Kornrawee
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Panyayao, Natthawut
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Siriwongrungson, Vilailuck
Titanium dioxide (TiO<inf>2</inf>) was deposited on stainless steel 304 by pulsed-pressure metalorganic chemical vapor deposition (PP-MOCVD). Titanium tetraisopropoxide (TTIP) in toluene at the concentration of 0.5 mol% was used as the precursor. The deposition was conducted at the base pressure of 300 Pa and deposition temperatures were varied between 350°C and 400°C. At these deposition temperatures, anatase phase is expected for further photocatalysis study. The deposited TiO<inf>2</inf> thin films at the thickness of hundreds nanometers were analyzed using field emission scanning electron microscopy (FESEM) for surface morphology. X-ray diffraction (XRD) was applied for phase analysis. The contact angle was measured to study its relationship with surface morphology, grain size and phase. Finally, photocatalytic activity was investigated through the absorption of methylene blue using UV/Vis spectrophotometer. The deposited TiO<inf>2</inf> thin films were found to be rutile and anatase with various surface morphology and grain size depends on the deposition temperature. The hydrophobicity of depositedTiO<inf>2</inf> thin films tend to increase with the deposition temperature whereas the photocatalytic property depends on the microstructure of TiO<inf>2</inf> thin film.
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Preparation and photocatalytic activities of tio2-rgo nanocomposite catalysts for mb dye degradation over sunlight irradiation
(2018-01-01)
Sriwong, Chaval
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Choojun, Kittisak
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Tejangkura, Worapol
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Prasanseang, Warot
This research aims to investigate photocatalytic activities of titanium dioxide (TiO<inf>2</inf>) incorporated with reduced graphene oxide (rGO) nanocomposite catalysts. These TiO<inf>2</inf>-rGO photocatalysts were easily prepared through a direct-mixing of TiO<inf>2</inf> powder suspended in acidic solution under the different amounts of rGO loading (0.25, 0.50, 0.75 and 1.00 wt%). Then, the obtained TiO<inf>2</inf>-rGO samples were characterized by a several techniques. The results demonstrated that the crystalline phases of all samples are corresponding to pristine TiO<inf>2</inf>, whereas the characteristic peaks of rGO in the TiO<inf>2</inf>-rGO nanocomposites could be observed and also confirmed by Raman spectroscopy. TEM results showed that the TiO<inf>2</inf> nanoparticles were well-combined with rGO nanosheets. Moreover, the photocatalytic activities of all TiO<inf>2</inf>-rGO photocatalyst samples were evaluated by photodegrading of methylene blue (MB) dye solution under natural sunlight irradiation. The results revealed that all TiO<inf>2</inf>-rGO nanocatalysts exhibited much higher activity than those of the bare TiO<inf>2</inf>. The improved photocatalytic activity can be attributed to the presence of rGO nanosheets, leading to the decrease of electron (e-)-hole (h+) recombination of TiO<inf>2</inf> catalyst, increasing charge transfer rate of electrons and surface-adsorbed amount of MB molecules which enhances the photocatalytic activity.
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Xylitol and gluconic acid productions via photocatalytic-glucose conversion using TiO2 fabricated by surfactant-assisted techniques: Effects of structural and textural properties
(2017-08-01)
Payormhorm, Jiraporn
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Chuangchote, Surawut
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Kiatkittipong, Kunlanan
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Chiarakorn, Siriluk
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Laosiripojana, Navadol
High-value chemicals can be converted from biomass and its derivatives by various methods. In this work, gluconic acid was obtained from photocatalytic conversion of glucose with synthesized TiO<inf>2</inf>. Moreover, another high-value chemical, xylitol, was firstly found from the photocatalysis in this work. Arabinose and formic acid are other co-products obtained from the reactions. Two surfactants, polyethylene glycol (PEG) and cetyltrimethylammonium bromide (CTAB), were used in conventional sol-gel (SG), ultrasonication sol-gel (US), and hydrothermal (HD) methods to fabricate TiO<inf>2</inf> with different structural and textural properties. Appropriate surface area and phase composition of TiO<inf>2</inf> for production of the highest yields of gluconic acid and xylitol were investigated. It was found that all surfactant-assisted fabrications increased surface area and anatase content of TiO<inf>2</inf> photocatalysts, resulting in high glucose conversion and high yields of xylitol, arabinose and formic acid. The highest yield of xylitol (6.45%) was obtained from US/CTAB-TiO<inf>2</inf>. Unfortunately, the yield of gluconic acid did not increase by increasing time, because it was also decomposed during photocatalysis. The moderate photocatalysis was found from SG/PEG-TiO<inf>2</inf> (100% anatase, surface area 5.93 m2/g) that provided the highest yield of gluconic acid (7.6%) in 120 min.
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Preparation, characterization and photocatalytic properties of rubber-TiO2-rGO composite sheets for dye decomposition in wastewater
(2017-01-01)
Tejangkura, Worapol
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Sriwong, Chaval
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Choojun, Kittisak
In this work, rubber-TiO<inf>2</inf>-rGO (RT-rGO) composite sheets were successfully prepared by a simple latex mixing-casting method using TiO<inf>2</inf> and natural rubber latex with different amounts of rGO loading. The prepared RT-rGO sheet samples were characterized by XRD, FT-IR, Raman, SEM and EDS techniques. The photocatalytic properties of the prepared RT-rGO sheets as catalyst were evaluated using methylene blue (MB) dye solution under UV light irradiation. The result indicated that all the composite sheets loaded with rGO had better photocatalytic activities than the sheet without rGO loading. RT-rGO6.2% sheet showed the highest removal efficiency of 93.3% which has the rate constant (kapp) as 98.2 times higher than the unloaded sheet. Furthermore, the efficiency of the RT-rGO sheet upon the repeated usage was also studied. The result indicated that the sheet could be easily used, recovered and reused many times with no need for the cleaning in between successive uses. Thus, the RT-rGO sheet appears to be an attractive-material for the wastewater treatment or the water purification industry.

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