scholarly journals Enhanced Photocatalytic Performance and Mechanism of Au@CaTiO3 Composites with Au Nanoparticles Assembled on CaTiO3 Nanocuboids

Micromachines ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 254 ◽  
Author(s):  
Yuxiang Yan ◽  
Hua Yang ◽  
Zao Yi ◽  
Ruishan Li ◽  
Xiangxian Wang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Photocatalytic Performance ◽  
Au Nanoparticles ◽  
Diffuse Reflectance Spectroscopy ◽  
Localized Surface Plasmon ◽  
Hydrothermal Route ◽  
Electron Hole ◽  
Photoexcited Electron ◽  
Au Nps ◽  
X Ray

Using P25 as the titanium source and based on a hydrothermal route, we have synthesized CaTiO3 nanocuboids (NCs) with the width of 0.3–0.5 μm and length of 0.8–1.1 μm, and systematically investigated their growth process. Au nanoparticles (NPs) of 3–7 nm in size were assembled on the surface of CaTiO3 NCs via a photocatalytic reduction method to achieve excellent Au@CaTiO3 composite photocatalysts. Various techniques were used to characterize the as-prepared samples, including X-ray powder diffraction (XRD), scanning/transmission electron microscopy (SEM/TEM), diffuse reflectance spectroscopy (UV-vis DRS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Rhodamine B (RhB) in aqueous solution was chosen as the model pollutant to assess the photocatalytic performance of the samples separately under simulated-sunlight, ultraviolet (UV) and visible-light irradiation. Under irradiation of all kinds of light sources, the Au@CaTiO3 composites, particularly the 4.3%Au@CaTiO3 composite, exhibit greatly enhanced photocatalytic performance when compared with bare CaTiO3 NCs. The main roles of Au NPs in the enhanced photocatalytic mechanism of the Au@CaTiO3 composites manifest in the following aspects: (1) Au NPs act as excellent electron sinks to capture the photoexcited electrons in CaTiO3, thus leading to an efficient separation of photoexcited electron/hole pairs in CaTiO3; (2) the electromagnetic field caused by localized surface plasmon resonance (LSPR) of Au NPs could facilitate the generation and separation of electron/hole pairs in CaTiO3; and (3) the LSPR-induced electrons in Au NPs could take part in the photocatalytic reactions.

CeO2/TiO2 Nanotubes Composites: Synthesis, Characterization, and Photocatalytic Properties

2012 ◽  
Vol 583 ◽  
pp. 86-90 ◽  
Author(s):  
Hai Bin Li ◽  
Xin Yong Li ◽  
Yan De Song ◽  
Shu Guang Chen ◽  
Ying Wang ◽  
...  
Keyword(s):  
Diffuse Reflectance Spectroscopy ◽  
Atomic Ratio ◽  
X Ray Diffraction ◽  
Hydrothermal Route ◽  
Electron Hole ◽  
Calcination Process ◽  
X Ray ◽  
Transmission Electron ◽  
Hole Recombination

TiO2nanotubes were prepared via a hydrothermal route. CeO2nanoparticles with diameters around 5nm were loaded onto the surface of TiO2nanotubes via a deposition approach followed by a calcination process. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectroscopy (UV-vis) were applied for the characterization of the as-prepared CeO2/TiO2nanotubes composites. The results show that CeO2particles are highly dispersed on the surface of TiO2nanotubes. The TiO2 nanotubes are modified to response to the visible light due to the combination with CeO2. The CeO2/TiO2nanotubes composites with a CeO2/TiO2atomic ratio of 2.5% show a further improvement on the photocatalytic activity for degradation of Rhodamine B in water. The presence of CeO2improves the light absorption of TiO2nanotubes and inhibits the electron-hole recombination.

scholarly journals Synthesis, Characterization, and Photocatalytic Evaluation of Manganese (III) Phthalocyanine Sensitized ZnWO4 (ZnWO4MnPc) for Bisphenol A Degradation under UV Irradiation

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2139 ◽  
Author(s):  
Chukwuka Bethel Anucha ◽  
Ilknur Altin ◽  
Zekeriya Biyiklioglu ◽  
Emin Bacaksiz ◽  
Ismail Polat ◽  
...  
Keyword(s):  
Bisphenol A ◽  
Uv Irradiation ◽  
Photoelectron Spectroscopy ◽  
Photocatalytic Performance ◽  
Diffuse Reflectance Spectroscopy ◽  
Degradation Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uv Visible ◽  
Adsorption Desorption

ZnWO4MnPc was synthesized via a hydrothermal autoclave method with 1 wt.% manganese (iii) phthalocyanine content. The material was characterized for its structural and morphological features via X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, transmission emission microscopy (TEM), scanning electron microscopy-Energy dispersive X-ray spectroscopy (SEM-EDX), N2 adsorption–desorption at 77K, X-ray photoelectron spectroscopy (XPS), and UV-visible/diffuse reflectance spectroscopy(UV-vis/DRS). ZnWO4MnPc photocatalytic performance was tested on the degradation of bisphenol A (BPA). The ZnWO4MnPc material removed 60% of BPA after 4 h of 365 nm UV irradiation. Degradation process improved significantly to about 80% removal in the presence of added 5 mM H2O2 after 4 h irradiation. Almost 100% removal was achieved after 30 min under 450 nm visible light irradiation in the presence of same concentration of H2O2. The effect of ions and humic acid (HA) towards BPA removal was also investigated.

scholarly journals Vis-Responsive Copper-Modified Titania for Decomposition of Organic Compounds and Microorganisms

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1194
Author(s):  
Maya Endo-Kimura ◽  
Bariş Karabiyik ◽  
Kunlei Wang ◽  
Zhishun Wei ◽  
Bunsho Ohtani ◽  
...  
Keyword(s):  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Water Oxidation ◽  
Diffuse Reflectance Spectroscopy ◽  
Antimicrobial Properties ◽  
Localized Surface Plasmon ◽  
Intrinsic Activity ◽  
Ambient Conditions ◽  
Copper Species ◽  
X Ray

Seven commercial titania (titanium(IV) oxide; TiO2) powders with different structural properties and crystalline compositions (anatase/rutile) were modified with copper by two variants of a photodeposition method, i.e., methanol dehydrogenation and water oxidation. The samples were characterized by diffuse reflectance spectroscopy (DRS), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Although zero-valent copper was deposited on the surface of titania, oxidized forms of copper, post-formed in ambient conditions, were also detected in dried samples. All samples could absorb visible light (vis), due to localized surface plasmon resonance (LSPR) of zero-valent copper and by other copper species, including Cu2O, CuO and CuxO (x:1-2). The photocatalytic activities of samples were investigated under both ultraviolet (UV) and visible light irradiation (>450 nm) for oxidative decomposition of acetic acid. It was found that titania modification with copper significantly enhanced the photocatalytic activity, especially for anatase samples. The prolonged irradiation (from 1 to 5 h) during samples’ preparation resulted in aggregation of copper deposits, thus being detrimental for vis activity. It is proposed that oxidized forms of copper are more active under vis irradiation than plasmonic one. Antimicrobial properties against bacteria (Escherichia coli) and fungi (Aspergillus niger) under vis irradiation and in the dark confirmed that Cu/TiO2 exhibits a high antibacterial effect, mainly due to the intrinsic activity of copper species.

scholarly journals Noble metal-modified titania with visible-light activity for the decomposition of microorganisms

2018 ◽  
Vol 9 ◽  
pp. 829-841 ◽  
Author(s):  
Maya Endo ◽  
Zhishun Wei ◽  
Kunlei Wang ◽  
Baris Karabiyik ◽  
Kenta Yoshiiri ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Visible Light ◽  
Noble Metal ◽  
Visible Light Irradiation ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Light Irradiation ◽  
Localized Surface Plasmon ◽  
Mycelium Growth ◽  
X Ray

Commercial titania photocatalysts were modified with silver and gold by photodeposition, and characterized by diffuse reflectance spectroscopy (DRS), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM). It was found that silver co-existed in zero valent (core) and oxidized (shell) forms, whereas gold was mainly zero valent. The obtained noble metal-modified samples were examined with regard to antibacterial (Escherichia coli(E. coli)) and antifungal (Aspergillus niger(A. niger),Aspergillus melleus(A. melleus),Penicillium chrysogenum(P. chrysogenum),Candida albicans(C. albicans)) activity under visible-light irradiation and in the dark using disk diffusion, suspension, colony growth (“poisoned food”) and sporulation methods. It was found that silver-modified titania, besides remarkably high antibacterial activity (inhibition of bacterial proliferation), could also decompose bacterial cells under visible-light irradiation, possibly due to an enhanced generation of reactive oxygen species and the intrinsic properties of silver. Gold-modified samples were almost inactive against bacteria in the dark, whereas significant bactericidal effect under visible-light irradiation suggested that the mechanism of bacteria inactivation was initiated by plasmonic excitation of titania by localized surface plasmon resonance of gold. The antifungal activity tests showed efficient suppression of mycelium growth by bare titania, and suppression of mycotoxin generation and sporulation by gold-modified titania. Although, the growth of fungi was hardly inhibited through disc diffusion (inhibition zones around discs), it indicates that gold does not penetrate into the media, and thus, a good stability of plasmonic photocatalysts has been confirmed. In summary, it was found that silver-modified titania showed superior antibacterial activity, whereas gold-modified samples were very active against fungi, suggesting that bimetallic photocatalysts containing both gold and silver should exhibit excellent antimicrobial properties.

scholarly journals Growth Process and CQDs-modified Bi4Ti3O12 Square Plates with Enhanced Photocatalytic Performance

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 66 ◽  
Author(s):  
Xinxin Zhao ◽  
Hua Yang ◽  
Ziming Cui ◽  
Xiangxian Wang ◽  
Zao Yi
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Growth Process ◽  
Photocatalytic Performance ◽  
Simulated Sunlight ◽  
Hydrothermal Route ◽  
Electron Hole ◽  
X Ray ◽  
Photocurrent Spectroscopy

Bi4Ti3O12 square plates were synthesized via a hydrothermal route, and their growth process was systematically investigated. Carbon quantum dots (CQDs) were prepared using glucose as the carbon source, which were then assembled on the surface of Bi4Ti3O12 square plates via a hydrothermal route with the aim of enhancing the photocatalytic performance. XRD (X-ray powder diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), UV-vis DRS (diffuse reflectance spectroscopy), XPS (X-ray photoelectron spectroscopy), FTIR (Fourier transform infrared spectroscopy), PL (photoluminescence) spectroscopy, EIS (electrochemical impedance spectroscopy) and photocurrent spectroscopy were used to systematically characterize the as-prepared samples. It is demonstrated that the decoration of CQDs on Bi4Ti3O12 plates leads to an increased visible light absorption, slightly increased bandgap, increased photocurrent density, decreased charge-transfer resistance, and decreased PL intensity. Simulated sunlight and visible light were separately used as a light source to evaluate the photocatalytic activity of the samples toward the degradation of RhB in aqueous solution. Under both simulated sunlight and visible light irradiation, CQDs@Bi4Ti3O12 composites with an appropriate amount of CQDs exhibit obviously enhanced photocatalytic performance. However, the decoration of excessive CQDs gives rise to a decrease in the photocatalytic activity. The enhanced photocatalytic activity of CQDs-modified Bi4Ti3O12 can be attributed to the following reasons: (1) The electron transfer between Bi4Ti3O12 and CQDs promotes an efficient separation of photogenerated electron/hole pairs in Bi4Ti3O12; (2) the up-conversion photoluminescence emitted from CQDs could induce the generation of additional electron/hole pairs in Bi4Ti3O12; and (3) the photoexcited electrons in CQDs could participate in the photocatalytic reactions.

Synthesis of Hexahydroxy Strontium Stannate/Tin Dioxide Nanocomposites and Their Photocatalytic Properties for Gentian Violet

2021 ◽  
Vol 14 ◽  
Author(s):  
C.H. Yu ◽  
Z.Y. Xue ◽  
Y.J. Mao ◽  
J. F. Huang ◽  
F.H. Tao ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Photoelectron Spectroscopy ◽  
Tin Dioxide ◽  
Photocatalytic Performance ◽  
Diffuse Reflectance Spectroscopy ◽  
Irradiation Time ◽  
Gentian Violet ◽  
Human Beings ◽  
X Ray ◽  
Strontium Stannate

Background: Gentian violet dye released from industries into the environment has caused serious water pollution and is a significant environment pollutant to human beings owing to the toxicity. It is urgent to decrease the environmental pollution by removing gentian violet in the wastewater. Objective: The aim is to synthesize hexahydroxy strontium stannate/tin dioxide nanocomposites by a simple hydrothermal method without surfactants and research the photocatalytic performance for gentian violet degradation. Methods: Hexahydroxy strontium stannate/tin dioxide nanocomposites have been obtained via the hydrothermal method. The structure, size, morphology and photocatalytic performance were characterized by X-ray diffraction, electron microscopy, solid ultraviolet-visible diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. Results : The nanocomposites possess oven-shaped morphology with the size of less than 100 nm and are composed of hexagonal SrSn(OH)6 and tetragonal SnO2 phases. The band gap of the nanocomposites is 3.52 eV. 10 mg hexahydroxy strontium stannate/tin dioxide nanocomposites have the ability to completely degrade 10 mL gentian violet solution with the concentration of 10 mgL-1 under 6 h ultraviolet-visible light irradiation. Hydroxyl radical, hole and superoxide radical are main species for the gentian violet photocatalytic degradation using the nanocomposites. Conclusion: The hexahydroxy strontium stannate/tin dioxide nanocomposites show good photocatalytic performance for the GV degradation. The photocatalytic performance for gentian violet degradation using the hexahydroxy strontium stannate/tin dioxide nanocomposites depends on the irradiation time and content of the nanocomposites.

PREPARATION OF Au-LOADED TiO2 BY PHOTOCHEMICAL DEPOSITION AND OZONE PHOTOCATALYTIC DECOMPOSITION

2006 ◽  
Vol 13 (01) ◽  
pp. 51-55 ◽  
Author(s):  
PANKE HE ◽  
MIN ZHANG ◽  
DONGMEI YANG ◽  
JIANJUN YANG
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Au Nanoparticles ◽  
Diffuse Reflectance Spectroscopy ◽  
Removal Rate ◽  
Photocatalytic Decomposition ◽  
X Ray ◽  
Transmission Electron ◽  
Photocatalytic Removal ◽  
Photochemical Deposition

In this paper, Au -loaded TiO 2( Au/TiO 2) photocatalysts were prepared by photochemical deposition method and characterized by transmission electron microscopy, diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The results indicated the metallic Au nanoparticles were deposited on the surface of TiO 2 after the high-pressure mercury irradiation and regarded as an electronegative center. The photocatalytic decomposition of gaseous ozone was investigated on TiO 2 and Au -loaded TiO 2 at room temperature. Results indicated that the photocatalytic conversion of ozone can be improved by Au/TiO 2 and photocatalytic activity increased with the increase of the photodeposition time. The photocatalytic removal rate of ozone remained above 96% on the surface of 1% Au/TiO 2 with photodeposition for 120 min under black lamp irradiation for 20 h. Au cluster deposited on the surface of TiO 2 functioned not only as the electron trap center but also as the adsorption site of O 3 in photocatalytic reaction.

scholarly journals Design and fabrication of Ag3VO4/g-C3N4 heterostructure photocatalyst for enhanced visible light degradation of various organic pollutants

2021 ◽  
Author(s):  
N Sujatha ◽  
M Meenachi ◽  
S Mohammed Harshulkhanb ◽  
H.H Hegazy
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Light Irradiation ◽  
X Rays ◽  
Hydrothermal Route ◽  
X Ray ◽  
Visible Light Degradation

Abstract In later years, numerous viable photocatalysts have been created in order to illuminate the issues of natural toxins. In this work, heterostructured photocatalysts Ag3VO4/g-C3N4 were prepared by effortless hydrothermal route in order to anchor Ag3VO4 on the surface of the g-C3N4 nanosheets. The prepared samples were fairly characterized using X-ray diffraction (XRD), Energy dispersive analysis of X-rays (EDAX), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (UV-DRS), photoluminescence, and X-ray photoelectron spectroscopy (XPS) techniques. The photocatalytic activity of the samples was evaluated by degrading malachite green (MG) and 2,4 dimethyl phenol (DMP) in aqueous solution under visible light irradiation. Compared with Ag3VO4 and g-C3N4, the heterojuncted photocatalyst 50 wt% Ag3VO4/g-C3N4 exhibits the best activity such as high degradation efficiency (99%), high apparent constant (0.0923 min− 1) and long term stability towards DMP under visible light irradiation. The development of a phase scheme heterojunction between Ag3VO4 and g-C3N4 improved the photocatalytic efficiency of Ag3VO4/g-C3N4 composites. Furthermore, the porous structure of g-C3N4 and the effect of Ag surface plasmon resonance (SPR) speed up the isolation and transfer of electron-hole pairs, reducing the likelihood of recombination.

scholarly journals Preparation of Hollow Flower-Like Microspherical β-Bi2O3/BiOCl Heterojunction and High Photocatalytic Property for Tetracycline Hydrochloride Degradation

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 57 ◽  
Author(s):  
Shulin Kong ◽  
Zhaohui An ◽  
Wenwen Zhang ◽  
Zhihao An ◽  
Ming Yuan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Photocatalytic Performance ◽  
Diffuse Reflectance Spectroscopy ◽  
Physical Adsorption ◽  
Hollow Spheres ◽  
Photocatalytic Property ◽  
Photogenerated Electron ◽  
Tetracycline Hydrochloride ◽  
X Ray

Tetracycline cannot be effectively degraded in wastewater treatment. Therefore, the development of excellent photocatalysts is of significant importance for environmental protection. In this study, a β-Bi2O3/BiOCl heterojunction photocatalyst with hollow flower-like microspheres was successfully synthesized by the in-situ reaction of HCl and β-Bi2O3 hollow spheres. The prepared samples are characterized by Scanning electron microscopy, Transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 physical adsorption, UV-vis diffuse reflectance spectroscopy, and Photoluminescence. Then, research on the photocatalytic performance for the degradation of tetracycline hydrochloride was conducted. The results show that the photocatalytic performance of the β-Bi2O3/BiOCl composite is significantly better than the β-Bi2O3 and BiOCl. The increase in photocatalytic activity is due to the formation of a heterojunction between β-Bi2O3 and BiOCl, which effectively promotes the separation of photogenerated electron-hole pairs. Additionally, the heterojunction nanocomposite demonstrated the outstanding photocatalytic stability after five cycles, which indicates that the material can be used for water environment purification. This paper provides assistance for studying the photocatalytic mechanism of heterojunction photocatalytic materials.

scholarly journals AgBr/(Sr0.6Bi0.305)2Bi2O7 Heterostructured Composites: Fabrication, Characterization, and Significantly Enhanced Photocatalytic Activity

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 394 ◽  
Author(s):  
Xinling Wang ◽  
Di Zhu ◽  
Yan Zhong ◽  
Dianhui Wang ◽  
Chaohao Hu
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Photocatalytic Performance ◽  
Diffuse Reflectance Spectroscopy ◽  
Precipitation Method ◽  
Light Illumination ◽  
X Ray ◽  
Transmission Electron ◽  
Pyrochlore Type

The pyrochlore-type (Sr0.6Bi0.305)2Bi2O7 (SBO) containing Bi3+ and Bi5+ mixed valent states was first investigated as a photocatalyst in our very recent work. To further improve the photocatalytic performance, AgBr/SBO heterostructured composites were synthesized by using a deposition-precipitation method. The characterization of phase structure, morphology, microstructure, elemental composition, and optical properties of the obtained products were performed using X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM)TEM, X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic activity of samples was evaluated by degrading methylene blue under visible light illumination. AgBr/SBO composites possess high stability and significantly enhanced photocatalytic performance. The improvement of photocatalytic activity is due to the enhanced light absorption and the separation of photoinduced electrons and holes on the interface of AgBr/SBO heterostructured composites.

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