scholarly journals Construction of Z-Scheme g-C3N4/CNT/Bi2Fe4O9 Composites with Improved Simulated-Sunlight Photocatalytic Activity for the Dye Degradation

Micromachines ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 613 ◽  
Author(s):  
Lijing Di ◽  
Hua Yang ◽  
Tao Xian ◽  
Xiujuan Chen
Keyword(s):  
Photocatalytic Activity ◽  
Dye Degradation ◽  
Active Species ◽  
Simulated Sunlight ◽  
Acid Orange 7 ◽  
Electron Mediator ◽  
Sunlight Irradiation ◽  
Highly Efficient ◽  
Electron Migration ◽  
Photoelectrochemical Measurement

In this work, ternary all-solid-state Z-scheme g-C3N4/carbon nanotubes/Bi2Fe4O9 (g-C3N4/CNT/BFO) composites with enhanced photocatalytic activity were prepared by a hydrothermal method. The morphology observation shows that ternary heterojunctions are formed in the g-C3N4/CNT/BFO composites. The photocatalytic activity of the samples for the degradation of acid orange 7 was investigated under simulated sunlight irradiation. It was found that the ternary composites exhibit remarkable enhanced photocatalytic activity when compared with bare BFO and g-C3N4/BFO composites. The effect of the CNT content on the photocatalytic performance of the ternary composites was investigated. The photocatalytic mechanism of g-C3N4/CNT/BFO was proposed according to the photoelectrochemical measurement, photoluminescence, active species trapping experiment and energy-band potential analysis. The results reveal that the introduction of CNT as an excellent solid electron mediator into the ternary composites can effectively accelerate the electron migration between BFO and g-C3N4. This charge transfer process results in highly-efficient separation of photogenerated charges, thus leading to greatly enhanced photocatalytic activity of g-C3N4/CNT/BFO composites. Furthermore, the g-C3N4/CNT/BFO composites also exhibit highly-efficient photo-Fenton-like catalysis property.

scholarly journals Synthesis of Spherical Bi2WO6Nanoparticles by a Hydrothermal Route and Their Photocatalytic Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
B. Wang ◽  
H. Yang ◽  
T. Xian ◽  
L. J. Di ◽  
R. S. Li ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Dye Degradation ◽  
Average Particle Size ◽  
Active Species ◽  
Bandgap Energy ◽  
Average Particle ◽  
Simulated Sunlight ◽  
Hydrothermal Route

Spherical Bi2WO6nanoparticles were synthesized by a hydrothermal route. SEM observation shows that the size of the particles ranges from 60 to 120 nm and the average particle size is ~85 nm. TEM investigation shows that the particles are made up of subgrains with size of 5–10 nm. The bandgap energy of the particles is measured to be 2.93 eV by ultraviolet-visible diffuse reflectance spectroscopy. RhB was chosen as the target pollutant to evaluate the photocatalytic activity of the particles under irradiation of simulated sunlight, revealing that they exhibit an obvious photocatalytic activity. The effects of ethanol, KI, and BQ on the photocatalytic efficiency of Bi2WO6particles towards the RhB degradation were investigated. It is observed that ethanol has no effect on the photocatalytic degradation of RhB, whereas KI and BQ exhibit a substantial suppression of RhB degradation. No hydroxyl (•OH) is found, by the photoluminescence technique using terephthalic acid as a probe molecule, to be produced over the irradiated Bi2WO6particles. Based on the experimental results, photoexcited hole (h+) and superoxide (•O2-) are suggested to be the two main active species responsible for the dye degradation, while •OH plays a negligible role in the photocatalysis.

scholarly journals Fabrication of a TiO 2 @porphyrin nanofiber hybrid material: a highly efficient photocatalyst under simulated sunlight irradiation

2017 ◽  
Vol 8 (1) ◽  
pp. 015009 ◽  
Author(s):  
Duong Duc La ◽  
Anushri Rananaware ◽  
Hoai Phuong Nguyen Thi ◽  
Lathe Jones ◽  
Sheshanath V Bhosale
Keyword(s):  
Hybrid Material ◽  
Simulated Sunlight ◽  
Sunlight Irradiation ◽  
Highly Efficient

scholarly journals In Situ Construction of a MgSn(OH)6 Perovskite/SnO2 Type-II Heterojunction: A Highly Efficient Photocatalyst towards Photodegradation of Tetracycline

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 53 ◽  
Author(s):  
Yuanyuan Li ◽  
Xiaofang Tian ◽  
Yaoqiong Wang ◽  
Qimei Yang ◽  
Yue Diao ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Ultraviolet Irradiation ◽  
Photocatalytic Oxidation ◽  
Photocatalytic Performance ◽  
Diffuse Reflectance Spectroscopy ◽  
Active Species ◽  
Growth Strategy ◽  
Type Ii ◽  
Highly Efficient

Using solar energy to remove antibiotics from aqueous environments via photocatalysis is highly desirable. In this work, a novel type-II heterojunction photocatalyst, MgSn(OH)6/SnO2, was successfully prepared via a facile one-pot in situ hydrothermal method at 220 °C for 24 h. The obtained heterojunctions were characterized via powder X-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, and ultraviolet-visible diffuse reflectance spectroscopy. The photocatalytic performance was evaluated for photodegradation of tetracycline solution under ultraviolet irradiation. The initial concentration of tetracycline solution was set to be 20 mg/L. The prepared heterojunctions exhibited superior photocatalytic activity compared with the parent MgSn(OH)6 and SnO2 compounds. Among them, the obtained MgSn(OH)6/SnO2 heterojunction with MgCl2·6H2O:SnCl4·5H2O = 4:5.2 (mmol) displayed the highest photocatalytic performance and the photodegradation efficiency conversion of 91% could be reached after 60 min under ultraviolet irradiation. The prepared heterojunction maintained its performance after four successive cycles of use. Active species trapping experiments demonstrated that holes were the dominant active species. Hydroxyl radicals and superoxide ions had minor effects on the photocatalytic oxidation of tetracycline. Photoelectrochemical measurements were used to investigate the photocatalytic mechanism. The enhancement of photocatalytic activity could be assigned to the formation of a type-II junction photocatalytic system, which was beneficial for efficient transfer and separation of photogenerated electrons and holes. This research provides an in situ growth strategy for the design of highly efficient photocatalysts for environmental restoration.

Enhanced Photocatalytic Performance and Mechanism of Ag3PO4 Particles Synthesized via a Sonochemical Process

2018 ◽  
Vol 10 (3) ◽  
pp. 337-345 ◽  
Author(s):  
Chengxiang Zheng ◽  
Hua Yang ◽  
Yang Yang ◽  
Haimin Zhang
Keyword(s):  
Particle Size ◽  
Photocatalytic Activity ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Ph Value ◽  
Dye Degradation ◽  
Sonochemical Method ◽  
Simulated Sunlight ◽  
Spherical Nanoparticles ◽  
Direct Oxidation

A facile sonochemical method was used to synthesize Ag3PO4 particles and the effect of pH value, reaction temperature and reaction time on the products was investigated. It is found that the samples prepared at neutral (pH = 7) and alkaline (pH = 11) environments exhibit a similar particle morphology and size. The particles are shaped like spheres with a size distribution majorly focusing on a range of 200–450 nm, and the average particle size is about 300 nm. The sample prepared at acidic environment (pH = 3) is composed of polyhedral microparticles with size of 5–8 μm. At relatively low temperatures of 20–50 °C, the spherical nanoparticles do not undergo obvious morphology/size changes; however, when the temperature is increased up to 80 °C, the nanoparticles are aggregated to form large-sized polyhedral microparticles in the size range of 4–7 μm. Compared to the pH value and reaction temperature, the reaction time has a minor effect on the morphology of Ag3PO4 particles. RhB was chosen as the target pollutant to evaluate the photocatalytic activity of the as-prepared Ag3PO4 samples under simulated-sunlight irradiation. It is shown that the samples consisting of spherical nanoparticles exhibit an extremely high photocatalytic activity, and the degradation percentage of RhB after reaction for 50 min reaches over 90%. The samples of polyhedral microparticles have a relatively low photocatalytic activity, which is possibly due to their large particle size. Hydroxyl (.OH) radical was detected by spectrofluorimetry using terephthalic acid as a .OH scavenger and was not found to be produced over the simulated-sunlight-irradiated Ag3PO4 catalyst. The effect of ethanol, benzoquinone and ammonium oxalate on dye degradation was also investigated. Based on experimental results, the direct oxidation by h+ is suggested to the dominant mechanism toward the dye degradation.

scholarly journals Bifunctional g-C3N4/WO3 Thin Films for Photocatalytic Water Purification

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2439 ◽  
Author(s):  
Maria Antoniadou ◽  
Michalis K. Arfanis ◽  
Islam Ibrahim ◽  
Polycarpos Falaras
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Dye Degradation ◽  
Active Species ◽  
Blue Dye ◽  
Pseudo First Order Reaction ◽  
Uv Illumination ◽  
Bilayered Structure ◽  
Reaction Constants

A bifunctional thin film photocatalyst consisting of graphitic carbon nitride on tungsten trioxide (g-C3N4/WO3) is introduced for the improvement of photocatalytic activity concerning hexavalent chromium reduction and methylene blue dye removal in water, compared to the bare, widely used WO3 semiconductor. A bilayered structure was formed, which is important for the enhancement of the charge carriers’ separation. The characterization of morphological, structural, optoelectronic, and vibrational properties of the photocatalysts permitted a better understanding of their photocatalytic activity for both dye degradation and Cr+6 elimination in water and the analysis of the photocatalytic kinetics permitted the determination of the corresponding pseudo-first-order reaction constants (k). Trapping experiments performed under UV illumination revealed that the main active species for the photocatalytic reduction of Cr+6 ions are electrons, whereas in the case of methylene blue azo-dye (MB) oxidation, the activation of the corresponding photocatalytic degradation comes via both holes and superoxide radicals.

Powder-based (CuGa1−yIny)1−xZn2xS2 solid solution photocathodes with a largely positive onset potential for solar water splitting

2018 ◽  
Vol 2 (9) ◽  
pp. 2016-2024 ◽  
Author(s):  
Toshio Hayashi ◽  
Ryo Niishiro ◽  
Hitoshi Ishihara ◽  
Masaharu Yamaguchi ◽  
Qingxin Jia ◽  
...  
Keyword(s):  
Solid Solution ◽  
Water Splitting ◽  
Simulated Sunlight ◽  
Sunlight Irradiation ◽  
Onset Potential ◽  
Solar Water ◽  
Solar Water Splitting ◽  
Highly Efficient

(CuGa1−yIny)1−xZn2xS2 has arisen as a highly efficient powder-based photocathode for water splitting under simulated sunlight irradiation.

Preparation and Modification of Y2Cu2O5/Y2O3 Photocatalysts for H2 Evolution under Simulated Sunlight Irradiation

2011 ◽  
Vol 239-242 ◽  
pp. 3001-3004 ◽  
Author(s):  
Li Zhang ◽  
Ke Long Huang ◽  
Hao Chen ◽  
Jian Hui Yan
Keyword(s):  
Photocatalytic Activity ◽  
Hydrogen Production ◽  
Production Rate ◽  
Hydrogen Reduction ◽  
Sol Gel ◽  
Oxalic Acid Solution ◽  
Impregnation Method ◽  
Simulated Sunlight ◽  
Hydrogen Production Rate ◽  
Sunlight Irradiation

Y2Cu2O5/Y2O3 (YCO) photocatalysts were prepared using sol-gel method. The photocatalysts were modified by Pt particles to prepare Pt-loaded composite (Pt-YCO) using hydrogen reduction method, and NiO/YCO were synthesized by impregnation method. These obtained samples were characterized by thermogravimetry and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), and ultraviolet visible diffuse reflectance absorption spectra (UV-Vis DRS) techniques. Photocatalytic H2 evolution activity of the modified photocatalysts has been evaluated from aqueous oxalic acid solution used as sacrificial reagent under simulated sunlight irradiation. The result showed that when the concentration of the photocatalysts is 0.8 g·L-1， Pt-YCO photocatalyst exhibits higher photocatalytic activity compared with unloaded YCO. The hydrogen production rate is 4.12 mmol·h-1·g-1 with 1wt% loading amount of Pt, while the loading content is up to 2.5wt%, the hydrogen production rate of Pt-YCO photocatalyst deecreased instead. Whereas NiO/YCO composite exhibits less photocatalytic activity than that of pure YCO under the same conditions.

Preparation and Photocatalytic Activities of TiO2-rGO Nanocomposite Catalysts for MB Dye Degradation over Sunlight Irradiation

2018 ◽  
Vol 936 ◽  
pp. 47-52 ◽  
Author(s):  
Chaval Sriwong ◽  
Kittisak Choojun ◽  
Worapol Tejangkura ◽  
Warot Prasanseang
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Transfer Rate ◽  
Acidic Solution ◽  
Dye Degradation ◽  
Sunlight Irradiation ◽  
Charge Transfer Rate ◽  
Reduced Graphene ◽  
Photocatalytic Activities ◽  
Nanocomposite Catalysts

This research aims to investigate photocatalytic activities of titanium dioxide (TiO2) incorporated with reduced graphene oxide (rGO) nanocomposite catalysts. These TiO2-rGO photocatalysts were easily prepared through a direct-mixing of TiO2powder suspended in acidic solution under the different amounts of rGO loading (0.25, 0.50, 0.75 and 1.00 wt%). Then, the obtained TiO2-rGO samples were characterized by a several techniques. The results demonstrated that the crystalline phases of all samples are corresponding to pristine TiO2, whereas the characteristic peaks of rGO in the TiO2-rGO nanocomposites could be observed and also well-confirmed by Raman spectroscopy. TEM results showed that the TiO2nanoparticles were well-combined with rGO nanosheets. Moreover, the photocatalytic activities of all TiO2-rGO photocatalyst samples were evaluated by photodegrading of methylene blue (MB) dye solution under natural sunlight irradiation. The results revealed that all TiO2-rGO nanocatalysts exhibited much higher activity than those of the bare TiO2. The improved photocatalytic activity can be attributed to the presence of rGO nanosheets, leading to the decrease of electron (e-) - hole (h+) recombination of TiO2catalyst, increasing charge transfer rate of electrons and surface-adsorbed amount of MB molecules which enhances the photocatalytic activity.

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