On-demand shape and size purification of nanoparticle based on surface area

Nanoscale ◽  
2014 ◽  
Vol 6 (21) ◽  
pp. 13145-13153 ◽  
Author(s):  
Renming Liu ◽  
Jian-Hua Zhou ◽  
Zhang-Kai Zhou ◽  
Xueqin Jiang ◽  
Jiaming Liu ◽  
...  
Keyword(s):  
Metal Nanoparticles ◽  
Surface Area ◽  
Purification Method ◽  
On Demand ◽  
Different Shapes ◽  
Centrifugation Method ◽  
Shape And Size

To overcome the deficiencies of the traditional centrifugation method in on-demand purification of metal nanoparticles, we developed a surface-based purification method which can separate particles with the same mass but different shapes.

Catalysis with Transition Metal Nanoparticles of Different Shapes

2005 ◽  
Vol 900 ◽  
Author(s):  
Radha Narayanan ◽  
Mostafa A. El-Sayed
Keyword(s):  
Electron Transfer ◽  
Metal Nanoparticles ◽  
Palladium Nanoparticles ◽  
Transfer Reaction ◽  
Ostwald Ripening ◽  
Suzuki Reaction ◽  
Electron Transfer Reaction ◽  
Different Shapes ◽  
Colloidal Metal ◽  
Shape And Size

ABSTRACTColloidal metal nanoparticles have a high surface-to-volume ratio which makes them potentially attractive catalysts. Furthermore, atoms located at different facets, edges, or corners could show different catalytic activity. For this reason, different shapes could have different catalytic activities. In addition, surface atoms are so active that there could be significant changes in their shape and size during the course of nanocatalysis. As a result, a thorough examination on the effect of the catalytic process on the shape and size of colloidal metal nanoparticles after catalysis is necessary to fully evaluate their use in catalytic processes.In this paper, we briefly review our recent work on examining the shape dependence of nanocatalysis as well as the stability of platinum and palladium nanoparticles during the course of two reactions: the electron transfer reaction and the Suzuki reaction. It is found that nanocatalysis is indeed shape-dependent during the early stages of the electron transfer reaction. During the full course of the reaction, there are changes in the nanoparticle shape as well as changes in the activation energy that takes place. In the case of a relatively harsh reaction such as the Suzuki reaction, spherical palladium nanoparticles grow in size due to Ostwald ripening processes. Tetrahedral platinum nanoparticles catalyzing the Suzuki reaction transform into spherical shape and grow larger in size. We also conducted studies on the effect of individual reactants on the nanoparticle size and shape. In addition, the surface catalytic mechanisms of the reactions have been confirmed using spectroscopic tools such as FTIR and Raman spectroscopy. These kinds of studies will be very useful in the process of designing better nanocatalysts in the future.

scholarly journals Impact of Shape and Size of Catalysts on the Physical Properties and Pressure Drop in Fixed Bed Catalytic Systems

2020 ◽  
Vol 9 (6) ◽  
pp. 1103-1109
Keyword(s):  
Pressure Drop ◽  
Surface Area ◽  
Pore Volume ◽  
Fixed Bed ◽  
Catalyst Design ◽  
Fixed Bed Reactor ◽  
Bet Surface Area ◽  
Different Shapes ◽  
The Impact ◽  
Shape And Size

Catalyst shape and size selection is an important aspect of the industrial catalyst design. Shapes of different sizes were made using alumina and characterized using standard methods used in the industry. Tableting machine, extruder and granulating equipment were used for forming different catalytic shapes. The samples were characterized by BET surface area, pore volume (N2 adsorption and water pick-up) and the sphericity & voidage calculations were performed for different alumina shapes. The physical strength and bulk density of the shapes were analyzed using ASTM methods. Spheres exhibited highest pore volume as the forming process exert minimum external force to the material. BET Surface area of all the samples were found comparable. The impact of different shapes and sizes on the pressure drop across the bed was studied for different gas flow rates using a fixed bed reactor set-up. Sphericity & voidage were calculated for different shapes and sizes and a modified Ergun equation was used for theoretical evaluation of the pressure drop. The experimental & theoretical results were compared and the relative error was noted. The study showed how the theoretical and experimental values differ as non-ideality in the flow across the packed bed increases. For special shapes like trilobe extrusions, impro

A New Study of Shape and Size-dependent Properties of Nanocrystals Utilizing the Fractional Fourier Transform

2020 ◽  
Vol 5 (2) ◽  
pp. 165-174
Author(s):  
Aeshah Salem
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Surface Area ◽  
Fractional Fourier Transform ◽  
Fourier Transform Infrared ◽  
Chemical Dynamics ◽  
Znse Nanoparticles ◽  
Size Dependent ◽  
Shape And Size

Background: Possessions of components, described by their shape and size (S&S), are certainly attractive and has formed the foundation of the developing field of nanoscience. Methods: Here, we study the S&S reliant on electronic construction and possession of nanocrystals by semiconductors and metals to explain this feature. We formerly considered the chemical dynamics of mineral nanocrystals that are arranged according to the S&S not only for the big surface area, but also as a consequence of the considerably diverse electronic construction of the nanocrystals. Results: The S&S of models, approved by using the Fractional Fourier Transform Infrared Spectroscopy (FFTIR), indicate the construction of CdSe and ZnSe nanoparticles. Conclusion: In order to study the historical behavior of the nanomaterial in terms of S&S and estimate further results, the FFTIR was used to solve this project.

scholarly journals Nanopore design for exceptional rectification of DNA translocation

2021 ◽  
Author(s):  
Ngan Pham ◽  
Yao Yao ◽  
Chenyu Wen ◽  
Shiyu Li ◽  
Shuangshuang Zeng ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solid State ◽  
Surface Charge ◽  
Dna Translocation ◽  
Sensor Applications ◽  
Sensor Performance ◽  
On Demand ◽  
Dna Strands ◽  
Large Opening ◽  
Shape And Size

Abstract Solid-state nanopores (SSNPs) of on-demand shape and size can facilitate desired sensor performance. However, reproducible production of arrayed nanopores of predefined geometry is yet to demonstrate despite of numerous methods explored. Here, bowl-shape SSNPs combining unique properties of ultrathin membrane and tapering geometry are demonstrated. The bowl-SSNP upper opening is 100-120 nm in diameter, with the bottom opening reaching sub-5 nm. Numerical simulation reveals the formation of multiple electroosmotic vortexes (EOVs) originating from distributed surface charge around the pore-bowl. The EOVs determine, collaboratively with electrophoretic force, how nanoscale objects translocate the bowl-SSNPs. Exceptional rectification with higher frequencies, longer duration and larger amplitude is found when DNA strands translocate downwards from the upper large opening than upwards from the bottom smallest restriction. The rectification is a manifestation of the interplay between electrophoresis and electroosmosis. The resourceful silicon nanofabrication technology is ingeniously shown to enable innovative nanopore designs targeting unprecedented sensor applications.

Metal nanoparticles: ligand free approach towards coupling reactions

2021 ◽  
Vol 01 ◽  
Author(s):  
Sharwari K. Mengane ◽  
Ronghui Wu ◽  
Liyun Ma ◽  
Chhaya S. Panse ◽  
Shailesh N. Vajekar ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Metal Nanoparticles ◽  
Surface Area ◽  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Reaction Medium ◽  
Coupling Reactions ◽  
Research Activities ◽  
Ligand Free

: Catalysis is the multidisciplinary field involving many areas of chemistry, notably in organometallic chemistry and materials science. It has great applications in synthesis of many industrially applicable compounds such as fuels and fine chemicals. The activity and selectivity are a key issue in catalysis that generally allied to high surface area. The current research activities mainly deal with the homogeneous and heterogeneous catalysis. Homogeneous and heterogeneous catalysis have certain drawbacks which restricts their application to great extent but have their own advantages. Hence, it has a predominant concern of current research to find out an alternate to overcome their drawbacks. Therefore, it is highly desirable to find a catalytic protocol that offers high selectivity and excellent product yield with quick and easy recovery. Along with their various applications as alternatives to conventional bulk materials nanomaterial have established its great role in different industrial and scientific applications. Nanocatalysis has emerged as new alternative to the conventional homogeneous and heterogeneous catalysis. The nanomaterials are responsible to enhance surface area of the catalyst, which ultimately increases the catalyst reactants contacts. In addition, it acts as robust material and has high surface area like heterogeneous catalysts. Insolubility of such nanomaterial in reaction medium makes them easily separable, hence, catalyst can be easily separate from the product. Hence, it has been proven that nanocatalysts behave like homogeneous as well as heterogeneous catalysts which work as a bridge between the conventional catalytic systems. Considering these merits; researchers has paid their attention towards applications of nanocatalyst in several organic reactions. This review article focused on the catalytic applications of metal nanoparticles (MNPs) such as Pd, Ag, Au, Cu, Pt in ligand free coupling reactions. In addition, it covers applications of bimetallic and multimetallic nanoparticles in ligand free coupling reactions.

scholarly journals Metal Nanoparticles as Green Catalysts

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3602 ◽  
Author(s):  
Neel Narayan ◽  
Ashokkumar Meiyazhagan ◽  
Robert Vajtai
Keyword(s):  
Catalytic Activity ◽  
Composite Materials ◽  
Green Synthesis ◽  
Metal Nanoparticles ◽  
Surface Area ◽  
Significant Role ◽  
High Surface ◽  
High Surface Area ◽  
Catalytic Performance ◽  
Materials Development

Nanoparticles play a significant role in various fields ranging from electronics to composite materials development. Among them, metal nanoparticles have attracted much attention in recent decades due to their high surface area, selectivity, tunable morphologies, and remarkable catalytic activity. In this review, we discuss various possibilities for the synthesis of different metal nanoparticles; specifically, we address some of the green synthesis approaches. In the second part of the paper, we review the catalytic performance of the most commonly used metal nanoparticles and we explore a few roadblocks to the commercialization of the developed metal nanoparticles as efficient catalysts.

Numerical Investigation of Melt Jet Breakup With Different Shapes in Water Pool

2017 ◽  
Author(s):  
Hui Cheng ◽  
Jiyun Zhao
Keyword(s):  
Surface Area ◽  
Steam Explosion ◽  
Nuclear Power ◽  
3D Model ◽  
Severe Accident ◽  
Interface Surface ◽  
Jet Breakup ◽  
Different Shapes ◽  
Interface Surface Area ◽  
2D Model

During a severe accident in nuclear power plant, core damage may occur due to decay heat and molten fuel can pour into and interact with water resulting in steam explosion. The energetics of steam explosion strongly depends on the initial premixing stage during which the molten fuel undergoes a coarse fragmentation process, which determines the surface area for fuel-coolant contact and heat transfer. Extensive research has been done to understand the premixing stage, however, most of the studies are focused on the cylindrical jet interaction with water. In fact, during core melt, the molten fuel may pour near the edge of core, so the shapes and size of melt jet may differ significantly based on specific conditions. In this paper, numerically study on the melt jet breakup with different shapes in pool water are conducted, such as elliptical shape with VOF method. Firstly, the deformation of molten jet under the same conditions in 2D model is compared with 3D model and shows that the breakup of 3D model is quite different from 2D model, the integration of 3D model is maintained much better than 2D model. Then the characteristics of breakup of elliptic cylindrical melt jet are analyzed and compared with cylindrical melt jet. The results shows that the interface surface area of elliptic cylindrical jet is nearly twice the cylindrical jet.

Redefinition of Denisiella Folsom & Mills, 1938 (Collembola: Sminthurididae) with description of three new species from Brazil

Zootaxa ◽  
2018 ◽  
Vol 4434 (1) ◽  
pp. 111
Author(s):  
JOSÉ G. PALACIOS-VARGAS ◽  
AILA SOARES FERREIRA ◽  
DOUGLAS ZEPPELINI
Keyword(s):  
Electron Microscope ◽  
New Species ◽  
Scanning Electron Microscope ◽  
Antennal Segment ◽  
Different Shapes ◽  
Three New Species ◽  
New Diagnosis ◽  
Scanning Electron ◽  
Shape And Size

A new diagnosis of Denisiella is provided, based on the revision of most descriptions, including three new species from Brazil. New Brazilian taxa share the presence of 6 + 6 eyes, 4 + 4 serrate spine-like on tibiotarsi III and the polycarinate setae on tibiotarsi II but differ from each other by the shape and size of the sensilla of the tibiotarsi I. Denisiella rhizophorae sp. nov. has the combination of sensilla on tibiotarsi I of rhagidial type and C2 blunt on antennal segment III. Only D. betschi sp. nov. has barbulate spines on head and D. caatingae sp. nov. is the only which males present nasal organ. They are illustrated with drawings and scanning electron microscope photographs. Three different shapes of sensilla in the tibiotarsi I were observed and were compared with other species. 

Applications of Gold Nanoparticles in Biosensors

Nano LIFE ◽  
2016 ◽  
Vol 06 (02) ◽  
pp. 1642001 ◽  
Author(s):  
Xinjun Yu ◽  
Yang Jiao ◽  
Qinyuan Chai
Keyword(s):  
Heavy Metals ◽  
Gold Nanoparticles ◽  
Optical Properties ◽  
Metal Nanoparticles ◽  
Surface Area ◽  
Surface Functionalization ◽  
High Surface ◽  
High Surface Area ◽  
Synthetic Methods ◽  
Future Perspective

Gold nanoparticles (AuNPs) as one of the most stable metal nanoparticles have demonstrated extensive applications in recent years. This paper will give a focus on the AuNPs as biosensors, due to their inertness, unique optical properties, high surface area, and various surface functionalization methods. Synthesis of AuNps and the surface functionalization will be discussed in the first part. The size, shape, and stability can be controlled by different synthetic methods, while reductant usually needed. By surface functionalization with different molecules such as polymers, nucleic acids, and proteins, AuNPs will aggregate when specified molecule linkages showing up enables selective detections. The application in biosensing to detect proteins, oligonucleotide, glucose, and heavy metals will be exemplified, followed by the summary and future perspective part in the conclusion.

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