Rapid synthesis of gold nanorods by the combination of chemical reduction and photoirradiation processes; morphological changes depending on the growing processes

It is known that the reactivity of the nanocatalytic systems is related to the particle size and shape and also to the features of the capping agents on the nanostructures. In this study, gold nanorods (AuNRs) were synthesized by the seed-mediated method using different tetraalkylammonium bromide salts as capping agents, that are, cetyltrimethylammonium (CTABr), N,N-dimethyl-N‑cetyl-N-(2-hydroxyethyl)ammonium (HEA16Br), and N,N-dimethyl-N-cetyl- N-(2-hydroxypropyl)ammonium (HPA16Br), and used as catalyst for the chemical reduction of p-nitrophenol (PNP) in the presence of NaBH4. The catalytic systems were characterized by ultraviolet-visible (UV-Vis) absorption spectroscopy and transmission electron microscopy (TEM). The effect of the ammonium bromide-based capping agent on the catalytic activity of AuNRs was evaluated by performing the chemical reduction of p-nitrophenol in the presence of excess NaBH4 in aqueous medium. Under the reaction conditions employed, the catalytic systems displayed detectable subtle differences in terms of induction times and apparent activation energy (Ea) values. These results show that slight changes carried out in the chemical structure of the capping agent are able to imprint even slightly modification of the kinetic parameter of the catalytic reaction.

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Electrochemical Reduction of CO2 using Copper Oxide Nanoparticles supported on Glassy Carbon Electrodes

MRS Proceedings ◽

10.1557/opl.2014.557 ◽

2014 ◽

Vol 1677 ◽

Cited By ~ 3

Author(s):

Gregory L. Griffin ◽

Joel Bugayong

Keyword(s):

Electrochemical Reduction ◽

Glassy Carbon ◽

Morphological Changes ◽

Chemical Reduction ◽

Product Distribution ◽

Product Formation ◽

Copper Oxide Nanoparticles ◽

Carbon Fiber Paper ◽

Cu Foil ◽

Reduction Of Co2

ABSTRACTWe have studied the electrochemical reduction of CO2 using Cu2O nanoparticles deposited on planar electrodes. Nanoparticles are prepared in aqueous solution by chemical reduction of CuCl2 using ascorbic acid with polyethylene glycol surfactant. The particles are then re-suspended in ethanol with added Nafion binder and brush-coated onto glassy carbon substrates. The CO2 electroreduction activity is measured in KHCO3 electrolyte under flowing CO2 using a two-compartment electrochemical cell. Product formation rates are determined using gas chromatography; major gas phase products include CO, H2, C2H4, and CH4, while liquid phase products include C2H5OH and 1-C3H5OH. The observed product distribution agrees with results obtained previously using similar Cu2O particles deposited on carbon fiber paper supports, as well as Cu2O catalysts prepared by electrodeposition or thermal oxidation. In particular, the catalysts produce a much higher ratio of C2H4 to CH4 than observed using polycrystalline Cu foil. The potential dependence of the formation rates for hydrocarbon and alcohol products is roughly two times greater than for H2 and CO formation. Both XRD and SEM measurements confirm the Cu2O nanoparticles undergo at least partial reduction to Cu metal under CO2 reduction conditions, accompanied by significant surface morphological changes. Thus the kinetic results are consistent with current models that the increased C2H4/CH4 ratio is due to the presence of a more open atomic structure on the freshly reduced Cu surfaces.

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Effect of a Silver Nanoparticles Solution onStaphylococcus aureusandCandidaspp.

Journal of Nanomaterials ◽

10.1155/2014/545279 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 12

Author(s):

Amanda Fucci Wady ◽

Ana Lucia Machado ◽

Camila Cristina Foggi ◽

Camila Andrade Zamperini ◽

Valtencir Zucolotto ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Activity ◽

Candida Glabrata ◽

Morphological Changes ◽

Chemical Reduction ◽

Total Biomass ◽

Systemic Diseases ◽

Planktonic Cells ◽

Sem Images ◽

Scanning Electron

An AgNPs solution was synthesized by chemical reduction, characterized, and tested againstCandida glabrata,Candida tropicalis,Staphylococcus aureus, and methicillin-resistantStaphylococcus aureus(MRSA). Minimum inhibitory (MICs) and minimum fungicidal/bactericidal concentrations (MFC/MBC) were determined on planktonic cells. Also, total biofilm mass was determined by crystal violet (CV) staining and morphological changes by scanning electron microscope (SEM). MICs forC. glabrata,C. tropicalis,S. aureus, and MRSA were 15.63, 3.91, 1.95, and 1.95 µg/mL, respectively. MFC forC. glabratawas 62.5 µg/mL and forC. tropicalis15.63 µg/mL The same MBC (3.91 µg/mL) was observed forS. aureusand MRSA. CV assay showed that the AgNPs (1000 μg/mL) promoted reductions in biofilm mass of ~60% forC. glabrataand ~35% forC. tropicalis. A reduction of ~20% inC. tropicalisbiomass was also observed at the concentration of 3.91 µg/mL. No significant effect on total biomass was found forS. aureusand MRSA. SEM images revealed thatC. glabrataandC. tropicalisbiofilm cells, exposed to the AgNPs (1000 μg/mL), had an irregular and shriveled appearance. AgNPs solution exhibited considerable antimicrobial activity against important fungal and bacterial pathogens, associated with several oral and systemic diseases, and has potential as an antimicrobial agent.

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Monitoring the death of single BaF3 cells under plasmonic photothermal heating induced by ultrasmall gold nanorods

Journal of Materials Chemistry B ◽

10.1039/c8tb03135e ◽

2019 ◽

Vol 7 (22) ◽

pp. 3582-3589 ◽

Cited By ~ 1

Author(s):

Lisa Prisner ◽

Phillip Witthöft ◽

Lan Vi Ngoc Nguyen ◽

Thomas Tsangas ◽

Tobias Gefken ◽

...

Keyword(s):

Optical Microscopy ◽

Gold Nanorods ◽

Trypan Blue ◽

Morphological Changes ◽

Single Cells ◽

Blue Staining ◽

Trypan Blue Staining ◽

Photothermal Heating

Morphological changes and trypan-blue staining are temporally tracked in single cells via optical microscopy after plasmonic photothermal heating.

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Preparation of Au@Ag Core-Shell Nanorods and Investigation of its Surface Plasmon

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.535-537.446 ◽

2012 ◽

Vol 535-537 ◽

pp. 446-449

Author(s):

Wei Yuan ◽

Pei Jie Wang ◽

Yan Fang

Keyword(s):

Aspect Ratio ◽

Surface Plasmon ◽

Gold Nanorods ◽

Chemical Reduction ◽

Silver Ions ◽

Blue Shift ◽

Core Shell ◽

Transverse Modes ◽

Growth Method ◽

Length Width

Different aspect ratio (length/width) gold nanorods were prepared in aqueous solution by seeding growth method. Aspect ratio of the nanorods was controlled accurately by changing the silver ions concentration. Ultraviolet-visible (UV-vis) spectra demonstrate the regularation that longitudinal plasmon resonance absorption wavelength of gold nanorods reveal red shift with the increase of aspect ratio. Gold nanorods were wrapped with Ag shells by chemical reduction silver ions on its surface. Different from gold nanorods, the transverse modes of the Au@Ag core-shell nanorods have two bands which contributed from the Ag and Au, respectively. On the other hand, centers of longitudinal surface plasmon of the core-shell nanorods exhibit blue shift with the Ag shell thickness increasing.

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