Charge behavior in a plasmonic photocatalyst composed of Au and TiO2

2018 ◽  
Vol 8 (7) ◽  
pp. 1813-1818 ◽  
Author(s):  
G. Kawamura ◽  
T. Arai ◽  
H. Muto ◽  
A. Matsuda
Keyword(s):  
Redox Reaction ◽  
Au Nanoparticle ◽  
Plasmonic Photocatalyst ◽  
Microanalytical Technique

Redox reaction sites on a Au nanoparticle-deposited TiO2 (Au/TiO2) plasmonic photocatalyst are visualized using a chemical microanalytical technique for investigating charge behaviors in Au/TiO2.

Some Aspects of Exelfs Analysis in the Electron Microscope

1980 ◽  
Vol 38 ◽  
pp. 118-119
Author(s):  
D. E. Johnson ◽  
S. Csillag
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Energy Loss ◽  
Analytical Electron Microscopy ◽  
Interference Effects ◽  
Interatomic Distances ◽  
X Ray ◽  
Structure Information ◽  
Microanalytical Technique ◽  
Analytical Electron

Recently, the applications area of analytical electron microscopy has been extended to include the study of Extended Energy Loss Fine Structure (EXELFS). Modulations past an ionization edge in the energy loss spectrum (EXELFS), contain atomic fine structure information similar to Extended X-ray Absorbtion Fine Structure (EXAFS). At low momentum transfer the main contribution to these modulations comes from interference effects between the outgoing excited inner shell electron waves and electron waves backscattered from the surrounding atoms. The ability to obtain atomic fine structure information (such as interatomic distances) combined with the spatial resolution of an electron microscope is unique and makes EXELFS an important microanalytical technique.

An Effort to Making a Colorimitric Nano-Biosensor for Vibrio cholera Detection

2020 ◽  
Vol 16 (5) ◽  
pp. 793-804
Author(s):  
Naimeh Mahheidari ◽  
Jamal Rashidiani ◽  
Hamid Kooshki ◽  
Khadijeh Eskandari
Keyword(s):  
Gold Nanoparticles ◽  
Colorimetric Assay ◽  
Au Nanoparticle ◽  
Bacteria Detection ◽  
Great Promise ◽  
Bacterial Cells ◽  
Vibrio Cholera ◽  
Minimum Concentration ◽  
Vis Spectroscopy ◽  
Fast Procedure

Background: Today, nanoparticles hold great promise in biomedical researches and applications including bacteria detection. The rapid and sensitive outcomes of bacteria detection strategies using nanoparticle conjugates become determinative, especially in bacterial outbreaks. In the current research, we focused on detecting V. cholera bacteria and its toxin using a thiocyanate/Au nanoparticle. Thiocyanate adsorbed strongly on the surface of gold nanoparticles and changed the surface by enhancing surface plasmon resonance of gold nanoparticles. Objective: This method is tried to introduce a simple and fast procedure to assay vibrio cholera. So, it is observed by the naked eyes as well. Methods: We used two antibodies (Ab) for V. cholera detection: a) a primary antibody conjugated to magnetic nanoparticles (MNPs) for trapping V. cholera bacterial cells, and b) a secondary Abconjugated thiocyanate-GNPs as a colorimetric detector. Then, an immuno-magnetic separation system connected to a colorimetric assay was designed based on the GNPs. The results were measured by ultraviolet-visible (UV-Vis) spectroscopy. Results: The results showed that gold nanoparticles are an appropriate optical assay for detecting biological samples in a minimum concentration and also it can be easily seen by the naked eyes. The linear range of this biosensor is 3.2×104 to 28×104 cells per ml. Conclusion: In this research, a colorimetric immune assay based on gold nanoparticles was designed to improve the sensitivity of V. cholera detection. Also, this method can be used for the detection of other biological agents.

Tuning the Photocatalytic Performance of Plasmonic Nanocomposites (ZnO/Aux) Driven in Visible Light

2019 ◽  
Vol 8 (1) ◽  
pp. 56-61
Author(s):  
Aneeya K. Samantara ◽  
Debasrita Dash ◽  
Dipti L. Bhuyan ◽  
Namita Dalai ◽  
Bijayalaxmi Jena
Keyword(s):  
Electron Transfer ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Transfer Rate ◽  
Photocatalytic Performance ◽  
Light Exposure ◽  
Au Nanoparticle ◽  
Electron Transfer Rate ◽  
Au Nps ◽  
Zno Nanostructure

: In this article, we explored the possibility of controlling the reactivity of ZnO nanostructures by modifying its surface with gold nanoparticles (Au NPs). By varying the concentration of Au with different wt% (x = 0.01, 0.05, 0.08, 1 and 2), we have synthesized a series of (ZnO/Aux) nanocomposites (NCs). A thorough investigation of the photocatalytic performance of different wt% of Au NPs on ZnO nanosurface has been carried out. It was observed that ZnO/Au0.08 nanocomposite showed the highest photocatalytic activity among all concentrations of Au on the ZnO surface, which degrades the dye concentration within 2 minutes of visible light exposure. It was further revealed that with an increase in the size of plasmonic nanoparticles beyond 0.08%, the accessible surface area of the Au nanoparticle decreases. The photon absorption capacity of Au nanoparticle decreases beyond 0.08% resulting in a decrease in electron transfer rate from Au to ZnO and a decrease of photocatalytic activity. Background: Due to the industrialization process, most of the toxic materials go into the water bodies, affecting the water and our ecological system. The conventional techniques to remove dyes are expensive and inefficient. Recently, heterogeneous semiconductor materials like TiO2 and ZnO have been regarded as potential candidates for the removal of dye from the water system. Objective: To investigate the photocatalytic performance of different wt% of Au NPs on ZnO nanosurface and the effect of the size of Au NPs for photocatalytic performance in the degradation process. Methods: A facile microwave method has been adopted for the synthesis of ZnO nanostructure followed by a reduction of gold salt in the presence of ZnO nanostructure to form the composite. Results: ZnO/Au0.08 nanocomposite showed the highest photocatalytic activity which degrades the dye concentration within 2 minutes of visible light exposure. The schematic mechanism of electron transfer rate was discussed. Conclusion: Raspberry shaped ZnO nanoparticles modified with different percentages of Au NPs showed good photocatalytic behavior in the degradation of dye molecules. The synergetic effect of unique morphology of ZnO and well anchored Au nanostructures plays a crucial role.

Non-Cottrell Behavior of the Dopamine Redox Reaction Observed on the Carbon Fibre Microelectrode by the Double-Step Voltcoulometry

2004 ◽  
Vol 69 (2) ◽  
pp. 419-425 ◽  
Author(s):  
Katarína Gmucová ◽  
Jozef Orlický ◽  
Juraj Pavlásek
Keyword(s):  
Carbon Fibre ◽  
Redox Reaction ◽  
Measured Data ◽  
The Other ◽  
Diffusion Current ◽  
Double Step ◽  
Dopamine Concentration ◽  
Living Body ◽  
Carbon Fibre Microelectrode ◽  
Experimental Errors

The redox reaction of the neurotransmitter dopamine at the carbon fibre microelectrode was studied by several electrochemical methods. It was found that under conditions usual in a living body, the diffusion current fullfils, within experimental errors, the behavior theoretically predicted by the Cottrell equation. Nevertheless, attention should be paid to the fact that unsupported or weakly supported conditions give rise to a non-Cottrell response of diffusion current. Moreover, similar changes were observed if the dopamine concentration was either lower such as several units of μmol l-1, or about 100 μmol l-1 or higher. The non-Cottrell behavior of diffusion current involves the nonlinearity of the dopamine calibration curve obtained by pulse techniques. The present work is aimed at pointing out that such behavior of the measured data could lead to misinterpretation of the obtained dopamine concentration. Similar features could be also achieved for the other catecholamines.

scholarly journals Effects of Au Nanoparticle Addition to Hole Transfer Layer in Organic Photovoltaic Cells Based on Phthalocyanines and Fullerene

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Akihiko Nagata ◽  
Takeo Oku ◽  
Tsuyoshi Akiyama ◽  
Atsushi Suzuki ◽  
Yasuhiro Yamasaki ◽  
...  
Keyword(s):  
Energy Levels ◽  
Photovoltaic Cells ◽  
Organic Photovoltaic ◽  
Au Nanoparticle ◽  
Molecular Orbital Calculations ◽  
Organic Photovoltaic Cells ◽  
Transfer Layer ◽  
Hole Transfer ◽  
Transmission Electron ◽  
Conversion Efficiencies

Phthalocyanines/fullerene organic photovoltaic cells were fabricated and characterized. Effects of Au nanoparticle addition to a hole transfer layer were also investigated, and power conversion efficiencies of the photovoltaic cells were improved after blending the Au nanoparticle into PEDOT:PSS. Nanostructures of the Au nanoparticles were investigated by transmission electron microscopy and X-ray diffraction. Energy levels of molecules were calculated by molecular orbital calculations, and the nanostructures and electronic property were discussed.

Tailored Design of Au Nanoparticle-siRNA Carriers Utilizing Reversible Addition−Fragmentation Chain Transfer Polymers∥

2010 ◽  
Vol 11 (4) ◽  
pp. 1052-1059 ◽  
Author(s):  
Stacey Kirkland-York ◽  
Yilin Zhang ◽  
Adam E. Smith ◽  
Adam W. York ◽  
Faqing Huang ◽  
...  
Keyword(s):  
Chain Transfer ◽  
Au Nanoparticle ◽  
Reversible Addition ◽  
Tailored Design
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