scholarly journals Microwave-Assisted Synthesis of Porous ZnO/SnS2Heterojunction and Its Enhanced Photoactivity for Water Purification

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
A. B. Makama ◽  
A. Salmiaton ◽  
E. B. Saion ◽  
T. S. Y. Choong ◽  
N. Abdullah
Keyword(s):  
Visible Light ◽  
Synergetic Effect ◽  
Visible Region ◽  
Microwave Assisted Synthesis ◽  
Fixed Amount ◽  
X Ray ◽  
Enhanced Absorption ◽  
Microwave Assisted ◽  
Degradation Rates ◽  
Photocatalytic Activities

Porous ZnO/SnS2nanocomposites with adjustable SnS2contents were prepared via microwave-assisted heating of different aqueous solutions of SnS2precursors in the presence of fixed amount of ZnCO3nanoparticles at pH 7. The structures, compositions, BET specific surface areas, and optical properties of the as-prepared products were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, N2adsorption, and UV-Vis absorption spectra. Photocatalytic activities of the samples were tested by the removal of aqueous ciprofloxacin,CrVI, and methylene blue under visible-light (λ>420 nm) irradiation. The experimental results reveal that the as-prepared heterogeneous nanostructures exhibit much higher visible-light-driven photocatalytic activity for the degradation of the pollutants than pure SnS2nanocrystals. The photocatalytic degradation ratesCt/C0of the pollutants for the most active heterogeneous nanostructure are about 10, 49, and 9 times higher than that of pure SnS2. The enhanced photocatalytic activities exhibited by the heterojunctions could be ascribed to the synergetic effect of enhanced absorption in the visible region and the reduced rate of charge carrier recombination because of efficient separation and electron transfer from the SnS2to ZnO nanoparticles.

scholarly journals Surfactant-Free Microwave-Assisted Synthesis of Fe-Doped ZnO Nanostars as Photocatalyst for Degradation of Tropaeolin O in Water under Visible Light

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Tsz-Lung Kwong ◽  
Ka-Fu Yung
Keyword(s):  
Visible Light ◽  
Photocatalytic Degradation ◽  
Irradiation Time ◽  
Catalyst Loading ◽  
Orthogonal Experimental Design ◽  
Microwave Assisted Synthesis ◽  
X Ray ◽  
Microwave Assisted ◽  
Vis Spectroscopy ◽  
Doped Zno

Iron-doped zinc oxide nanostar was synthesized by the microwave-assisted surfactant-free hydrolysis method. The as-synthesized Fe-doped ZnO nanostars catalyst was fully characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and diffuse reflectance UV-vis spectroscopy (UV-DRA). The photocatalytic activity of the photocatalyst was investigated for the photocatalytic degradation of Tropaeolin O under visible light irradiation. It is observed that the doping of Fe ions enhances the absorption of the visible light and thus the photocatalytic degradation rate of Tropaeolin O would increase. Despite the Taguchi orthogonal experimental design method, the photocatalytic conversion could be achieved at 99.8% in the Fe-doped ZnO catalyzed photodegradation reaction under the optimal reaction conditions of catalyst loading (30 mg), temperature (60°C), light distance (0 cm), initial pH (pH = 9), and irradiation time (3 h). The Fe-doped ZnO photocatalyst can also be easily recovered and directly reused for eight cycles with over 70% conversion.

scholarly journals Preparation of Fe-DopedTiO2Nanotubes and Their Photocatalytic Activities under Visible Light

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Honghui Teng ◽  
Shukun Xu ◽  
Dandan Sun ◽  
Ying Zhang
Keyword(s):  
Visible Light ◽  
Visible Region ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Transmission Electron ◽  
Photocatalytic Activities ◽  
Ultrasonic Assisted ◽  
Uv Visible

Fe-doped TiO2nanotubes (Fe-TNTs) have been prepared by ultrasonic-assisted hydrothermal method. The structure and composition of the as-prepared TiO2nanotubes were characterized by transmission electron microscopy, X-ray diffraction, and UV-Visible absorption spectroscopy. Their photocatalytic activities were evaluated by the degradation of MO under visible light. The UV-visible absorption spectra of the Fe-TNT showed a red shift and an enhancement of the absorption in the visible region compared to the pure TNT. The Fe-TNTs were provided with good photocatalytic activities and photostability and under visible light irradiation, and the optimum molar ratio of Ti : Fe was found to be 100 : 1 in our experiments.

scholarly journals Hydrothermal Synthesis of Iodine-Doped Nanoplates with Enhanced Visible and Ultraviolet-Induced Photocatalytic Activities

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Jiang Zhang ◽  
Zheng-Hong Huang ◽  
Yong Xu ◽  
Feiyu Kang
Keyword(s):  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Oxygen Vacancies ◽  
Diffuse Reflectance Spectroscopy ◽  
Synergetic Effect ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Photocatalytic Activities

The iodine-doped Bi2WO6(I-BWO) photocatalyst was prepared via a hydrothermal method using potassium iodide as the source of iodine. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of I-BWO for the degradation of rhodamine B (RhB) was higher than that of pure BWO and I2-BWO regardless of visible light (>420 nm) or ultraviolet light (<400 nm) irradiation. The results of DRS analysis showed that the I-BWO and I2-BWO catalysts had narrower band gaps. XPS analysis proved that the multivalent iodine species including I0and were coadsorbed on the defect surface of Bi2WO6in I-BWO. The enhanced PL intensity revealed that a large number of defects of oxygen vacancies were formed by the doping of iodine. The enhanced photocatalytic activity of I-BWO for degradation of RhB was caused by the synergetic effect of a small crystalline size, a narrow band gap, and plenty of oxygen vacancies.

Photocatalytic Decomposition of Methylene Blue with Lanthanum Doping TiO2 under Visible Light Irradiation

2013 ◽  
Vol 734-737 ◽  
pp. 2163-2167
Author(s):  
Guang Xiu Cao ◽  
Zhong Hou Zhang ◽  
Bin Zhai
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Photoelectron Spectroscopy ◽  
Light Irradiation ◽  
Photocatalytic Decomposition ◽  
Lanthanum Doping ◽  
X Ray ◽  
Degradation Rates ◽  
Vis Spectroscopy

Lanthanum doped TiO2 powders were prepared by hydrolysis of titanium tetra-n-butyl oxide and La (NO3)3 in solution. The resulting powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis absorption spectroscopy. The photocatalytic activities of doped samples were evaluated by the decomposition of methylene blue under visible light irradiation. The XRD results showed that the doping of lanthanum could not only efficiently inhibit the grain growth but also suppress the phase transition of anatase to rutile. UV-Vis spectroscopy of lanthanum doping TiO2 indicated that the absorption onset red-shifted to the visible light region. XPS results revealed that La2O3 had formed which could enhance the surface area. The degradation rates of methylene blue verified that the visible light photocatalytic activity of TiO2 has been enhanced by the doping of lanthanum.

scholarly journals The Photocatalytic and Antibacterial Performance of Nitrogen-Doped TiO2: Surface-Structure Dependence and Silver-Deposition Effect

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2261 ◽  
Author(s):  
Abdul Wafi ◽  
Erzsébet Szabó-Bárdos ◽  
Ottó Horváth ◽  
Mihály Pósfai ◽  
Éva Makó ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Surface Area ◽  
Photocatalytic Performance ◽  
Visible Region ◽  
Bet Surface Area ◽  
Doped Tio2 ◽  
X Ray ◽  
Nitrogen Doped ◽  
Visible Light Driven

Catalysts for visible-light-driven oxidative cleaning processes and antibacterial applications (also in the dark) were developed. In order to extend the photoactivity of titanium dioxide into the visible region, nitrogen-doped TiO2 catalysts with hollow and non-hollow structures were synthesized by co-precipitation (NT-A) and sol–gel (NT-U) methods, respectively. To increase their photocatalytic and antibacterial efficiencies, various amounts of silver were successfully loaded on the surfaces of these catalysts by using a facile photo-deposition technique. Their physical and chemical properties were evaluated by using scanning electron microscopy (SEM), transmission electron microscopy–energy dispersive X-ray spectroscopy (TEM–EDS), Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), and diffuse reflectance spectra (DRS). The photocatalytic performances of the synthesized catalysts were examined in coumarin and 1,4-hydroquinone solutions. The results showed that the hollow structure of NT-A played an important role in obtaining high specific surface area and appreciable photoactivity. In addition, Ag-loading on the surface of non-hollow structured NT-U could double the photocatalytic performance with an optimum Ag concentration of 10−6 mol g−1, while a slight but monotonous decrease was caused in this respect for the hollow surface of NTA upon increasing Ag concentration. Comparing the catalysts with different structures regarding the photocatalytic performance, silverized non-hollow NT-U proved competitive with the hollow NT-A catalyst without Ag-loading for efficient visible-light-driven photocatalytic oxidative degradations. The former one, due to the silver nanoparticles on the catalyst surface, displayed an appreciable antibacterial activity, which was comparable to that of a reference material practically applied for disinfection in polymer coatings.

scholarly journals Significantly Enhanced Aqueous Cr(VI) Removal Performance of Bi/ZnO Nanocomposites via Synergistic Effect of Adsorption and SPR-Promoted Visible Light Photoreduction

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 426 ◽  
Author(s):  
Xiaoya Yuan ◽  
Zijuan Feng ◽  
Jianjun Zhao ◽  
Jiawei Niu ◽  
Jiasen Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Synergistic Effect ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Diffuse Reflectance Spectroscopy ◽  
X Ray ◽  
Enhanced Absorption ◽  
Bismuth Nanoparticles ◽  
Effective Transfer

Bismuth nanoparticles (BiNPs) and Zinc Oxide photocatalysts (BiNPs/ZnO) with different Bi loadings were successfully prepared via a facile chemical method. Their morphology and structure were thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis (Ultraviolet-Visible) diffuse reflectance spectroscopy (DRS), photoluminescence spectra (PL), and electrochemical impedance spectroscopy (EIS). The results showed that a modification of hexagonal wurtzite-phase ZnO nanoparticles with Bi is achievable with an intimate interfacial interaction within its composites. The performance of the photocatalytic Cr(VI) removal under visible light irradiation indicated that BiNPs/ZnO exhibited a superior removal performance to bare ZnO, Bi, and the counterpart sample prepared using a physical mixing method. The excellent performance of the BiNPs/ZnO photocatalysts could be ascribed to the synergistic effect between the considerable physical Cr (VI) adsorption and enhanced absorption intensity in the visible light region, due to the surface plasmon resonance (SPR) as well as the effective transfer and separation of the photogenerated charge carriers at the interface.

scholarly journals Incorporation of reduced graphene oxide into faceted flower-like {001} TiO 2 for enhanced photocatalytic activity

2018 ◽  
Vol 5 (8) ◽  
pp. 180613 ◽  
Author(s):  
Haijin Liu ◽  
Peiyao Li ◽  
Haokun Bai ◽  
Cuiwei Du ◽  
Dandan Wei ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Graphene Oxide ◽  
Visible Light ◽  
Reduced Graphene Oxide ◽  
Theoretical Calculations ◽  
X Ray ◽  
Transmission Electron ◽  
Reduced Graphene ◽  
Photocatalytic Activities

Anatase TiO 2 with {001} facets is much more active than that with {101} facets, which has been verified via experiments and theoretical calculations. Graphene has garnered much attention since it was initially synthesized, due to its unique properties. In this study, reduced graphene oxide (RGO)/{001} faceted TiO 2 composites were fabricated via a solvothermal method. The composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectrophotometry, photoluminescence and Raman analysis. The results revealed that the graphene oxide was reduced during the preparation process of the {001} faceted TiO 2 , and combined with the surface of {001} TiO 2 . The photocatalytic activities of the composites were evaluated through the degradation of basic violet, under both white light ( λ > 390 nm) and visible light ( λ = 420 nm) irradiation. The results indicated that the photocatalytic activities of the {001} faceted TiO 2 were significantly improved following the incorporation of RGO, particularly under visible light irradiation. Theoretical calculations showed that the band structure of the {001} faceted TiO 2 was modified via graphene hybridization, where the separation of photoinduced electron–hole pairs was promoted; thus, the photocatalytic activity was enhanced.

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