Visible light-induced degradation of amoxicillin antibiotic by novel CuI/FePO4 p-n heterojunction photocatalyst and photodegradation mechanism

In this work, we report the fabrication of the new heterojunction of two 2D hybrid layered semiconductors—ZnO (stearic acid)/V2O5 (hexadecylamine)—and its behavior in the degradation of aqueous methylene blue under visible light irradiation. The optimal photocatalyst efficiency, reached at a ZnO (stearic acid)/V2O5 (hexadecylamine) ratio of 1:0.25, results in being six times higher than that of pristine zinc oxide. Reusability test shows that after three photocatalysis cycles, no significant changes in either the dye degradation efficiency loss, nor the photocatalyst structure, occur. Visible light photocatalytic performance observed indicates there is synergetic effect between both 2D nanocomposites used in the heterojunction. The visible light absorption enhancement promoted by the narrower bandgap V2O5 based components; an increased photo generated charge separation favored by extensive interface area; and abundance of hydrophobic sites for dye adsorption appear as probable causes of the improved photocatalytic efficiency in this hybrid semiconductors heterojunction. Estimated band-edge positions for both conduction and valence band of semiconductors, together with experiments using specific radical scavengers, allow a plausible photodegradation mechanism.

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Enhancement Photocatalytic Activity of the Heterojunction of Two-Dimensional Hybrid Semiconductors ZnO/V2O5

10.20944/preprints201807.0583.v1 ◽

2018 ◽

Author(s):

Juan Aliaga ◽

Nasla Cifuentes ◽

Guillermo Gonzalez ◽

Clivia Sotomayor-Torres ◽

Eglantina Benavente

Keyword(s):

Stearic Acid ◽

Visible Light ◽

Photocatalytic Performance ◽

Dye Degradation ◽

Synergetic Effect ◽

Dye Adsorption ◽

Absorption Enhancement ◽

Interface Area ◽

Photodegradation Mechanism ◽

Hybrid Semiconductors

In this work, we report the fabrication of the new heterojunction of two 2D hybrid layered semiconductors, ZnO(stearic acid)/V2O5(hexadecylamine), and its behavior in the degradation of aqueous methylene blue under visible light irradiation. The optimal photocatalyst efficiency, reached at a ZnO(stearic acid)/ V2O5(hexadecylamine) ratio of 1:0.25, results to be about six times higher than that of pristine zinc oxide. Reusability test shows that after three photocatalysis cycles no significant changes in neither the dye degradation efficiency loss nor photocatalyst structure occur. Visible light photocatalytic performance observed indicates there is synergetic effect between both 2D nanocomposites used in the heterojunction. The visible light absorption enhancement promoted by the narrower bandgap V2O5 based components; an increased photo generated charge separation favored by extensive interface area; and abundance of hydrophobic sites for dye adsorption appear as probable causes of the improved photocatalytic efficiency in this hybrid semiconductors heterojunction. Estimated band-edge positions for both conduction and valence band of semiconductors together with experiments using specific radical scavengers allow a plausible photodegradation mechanism.

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Studies of metaphase chromosomes in the scanning transmission x-ray microscope: Image fidelity, radiation damage and specimen preparation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129826 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1038-1039

Author(s):

Shawn Williams ◽

Xiaodong Zhang ◽

Susan Lamm ◽

Jack Van’t Hof

Keyword(s):

Visible Light ◽

Radiation Damage ◽

Cross Section ◽

Imaging Techniques ◽

Dose Range ◽

Specimen Preparation ◽

X Rays ◽

Metaphase Chromosomes ◽

X Ray ◽

Scanning Transmission

The Scanning Transmission X-ray Microscope (STXM) is well suited for investigating metaphase chromosome structure. The absorption cross-section of soft x-rays having energies between the carbon and oxygen K edges (284 - 531 eV) is 6 - 9.5 times greater for organic specimens than for water, which permits one to examine unstained, wet biological specimens with resolution superior to that attainable using visible light. The attenuation length of the x-rays is suitable for imaging micron thick specimens without sectioning. This large difference in cross-section yields good specimen contrast, so that fewer soft x-rays than electrons are required to image wet biological specimens at a given resolution. But most imaging techniques delivering better resolution than visible light produce radiation damage. Soft x-rays are known to be very effective in damaging biological specimens. The STXM is constructed to minimize specimen dose, but it is important to measure the actual damage induced as a function of dose in order to determine the dose range within which radiation damage does not compromise image quality.

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Scanning luminescence x-ray microscopy: Progress toward selective staining using microspheres

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168104 ◽

1994 ◽

Vol 52 ◽

pp. 74-75

Author(s):

C. Jacobsen ◽

J. Fu ◽

S. Mayer ◽

Y. Wang ◽

S. Williams

Keyword(s):

Visible Light ◽

Active Sites ◽

Light Emission ◽

Chinese Hamster ◽

Polystyrene Spheres ◽

Good Resistance ◽

X Ray ◽

Selective Staining ◽

Visible Light Emission ◽

Specific Labelling

In scanning luminescence x-ray microscopy (SLXM), a high resolution x-ray probe is used to excite visible light emission (see Figs. 1 and 2). The technique has been developed with a goal of localizing dye-tagged biochemically active sites and structures at 50 nm resolution in thick, hydrated biological specimens. Following our initial efforts, Moronne et al. have begun to develop probes based on biotinylated terbium; we report here our progress towards using microspheres for tagging.Our initial experiments with microspheres were based on commercially-available carboxyl latex spheres which emitted ~ 5 visible light photons per x-ray absorbed, and which showed good resistance to bleaching under x-ray irradiation. Other work (such as that by Guo et al.) has shown that such spheres can be used for a variety of specific labelling applications. Our first efforts have been aimed at labelling ƒ actin in Chinese hamster ovarian (CHO) cells. By using a detergent/fixative protocol to load spheres into cells with permeabilized membranes and preserved morphology, we have succeeded in using commercial dye-loaded, spreptavidin-coated 0.03μm polystyrene spheres linked to biotin phalloidon to label f actin (see Fig. 3).

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Photocatalyst-free decarboxylative aminoalkylation of imidazo[1,2-a]pyridines with N-aryl glycines enabled by visible light

Organic Chemistry Frontiers ◽

10.1039/c9qo00935c ◽

2019 ◽

Vol 6 (21) ◽

pp. 3693-3697 ◽

Cited By ~ 11

Author(s):

Jiu-Jian Ji ◽

Zhi-Qiang Zhu ◽

Li-Jin Xiao ◽

Dong Guo ◽

Xiao Zhu ◽

...

Keyword(s):

Visible Light

A novel, green and efficient visible-light-promoted decarboxylative aminoalkylation reaction of imidazo[1,2-a]pyridines with N-aryl glycines has been described.

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