Size and shape dependency of the surface energy of metallic nanoparticles: unifying the atomic and thermodynamic approaches

2018 ◽  
Vol 20 (31) ◽  
pp. 20575-20587 ◽  
Author(s):  
Bastiaan Molleman ◽  
Tjisse Hiemstra
Keyword(s):  
Surface Energy ◽  
Metallic Nanoparticles ◽  
Size Dependency ◽  
Size And Shape ◽  
Surface Of Tension

We identify the surface of tension for faceted, metallic nanoparticles, revealing the thermodynamically consistent size dependency of the surface energy.

Preparation of tailor-made supported catalysts using asymmetric flow field flow fractionation and their application in hydrogenation

2014 ◽  
Vol 3 (1) ◽  
pp. 87-98 ◽  
Author(s):  
Jens Baumgard ◽  
Marga-Martina Pohl ◽  
Udo Kragl ◽  
Norbert Steinfeldt
Keyword(s):  
Particle Size ◽  
Flow Field ◽  
Metallic Nanoparticles ◽  
Size Range ◽  
Separation Process ◽  
Proton Nuclear Magnetic Resonance ◽  
Field Flow Fractionation ◽  
Asymmetric Flow ◽  
Size And Shape ◽  
Flow Fractionation

AbstractThe optical, chemical, and catalytic properties of metallic nanoparticles (NPs) depend strongly on their particle size and shape. Therefore, the preparation of monodisperse metallic NPs is very important for fundamental studies and practical applications. However, the isolation of the different structures by separation from a polydisperse sample, especially in the size range below 10 nm, is not well applied so far. Here, the asymmetric flow field flow fractionation (AF4) is adapted for the preparative separation of the Pd NPs regarding their size and shape in the sub-10-nm size range. To prove the efficiency of the applied method, small-angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (TEM) were utilized to determine the particle size distribution at different stages of the separation process. A major benefit of this method compared to most of the other separation techniques, the removal of impurities during the separation process, was proven by proton nuclear magnetic resonance (NMR). The obtained results demonstrate that the AF4 is well suited for the rapid preparation of the purified uniform precious metal NPs at the applied size range. Single fractions of the different-sized and -shaped Pd NPs were deposited on titania (TiO2) and tested in the catalytic hydrogenation of 2,5 hydroxymethylfurfural (HMF) in aqueous solution under mild conditions. While the spherical-shaped particles show a high activity, the separated agglomerated particles show a higher selectivity to the desired products.

Size and Shape Dependent Surface Free Energy of Metallic Nanoparticles

2011 ◽  
Vol 8 (12) ◽  
pp. 2477-2481 ◽  
Author(s):  
Shiyun Xiong ◽  
Weihong Qi ◽  
Baiyun Huang ◽  
Mingpu Wang ◽  
Yajuan Cheng ◽  
...  
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Metallic Nanoparticles ◽  
Size And Shape

scholarly journals Synthesis, characterization and applications of chitosan based metallic nanoparticles: A review

2021 ◽  
Vol 13 (2) ◽  
pp. 544-551
Author(s):  
Devendra Kumar Verma ◽  
Rajdeep Malik ◽  
Jagram Meena ◽  
Rashmi Rameshwari
Keyword(s):  
Metallic Nanoparticles ◽  
Synthesis Methods ◽  
Controlled Synthesis ◽  
Metallic Nanoparticle ◽  
Size And Shape ◽  
Degree Of Acetylation ◽  
Important Host ◽  
The Subject ◽  
Medium Method ◽  
Reaction Degree

Chitosan as a natural biopolymer has been produced to be the important host for the preparation of metallic nanoparticles (MNPs) because of its excellent characteristics like:- good stabilizing and capping ability, biocompatibility, biodegradability, eco-friendly and non-toxicity properties. Chitosan can play a very important role for synthesis of metallic nanoparticles, as chitosan is a cationic polymer. It attracts metal ions and reduces them and also Capps and stabilizes. So basically chitosan can be responsible for the controlled synthesis of metallic nanoparticle. Chitosan has a very good chelating property. This property is due to its –NH2 and –OH functional groups. Size and shape of metallic nanoparticles are much affected by chitosan concentration, molecular weight, time of reaction, degree of acetylation of chitosan, pH of the medium, method of synthesis and type of derivative of chitosan etc. Metallic nanoparticles`s properties and applications are much associated with their size and shape. Optimization of the metallic nanoparticle size and shape has been the subject of curiosity for nanotechnology scientist. Chitosan can solve this problem by applying the optimization conditions. But a very little work is reported about: - how chitosan can affect the size and shape of metallic nanoparticles and how can it reduce metal salts to prepare metallic nanoparticle, stablilized in chitosan metrics. This is very first report as a review article highlighting the effect of chitosan on synthesis of metallic nanoparticles and optimization conditions. This review will also be beneficial for scientist working on food sensing application of nanoparticles.  Various synthesis methods and applications of chitosan based metallic nanoparticles have also been reported in details.

The Habit Plate Shift and the Morphology of ∝" Nitride Precipitate in ∝-Fe*

1982 ◽  
Vol 40 ◽  
pp. 728-729
Author(s):  
Y. C. Shih ◽  
J. W. Morris
Keyword(s):  
Surface Energy ◽  
Habit Plane ◽  
Elastic Strain ◽  
Strain Energy ◽  
Lattice Mismatch ◽  
Parent Phase ◽  
Elastic Strain Energy ◽  
Size And Shape ◽  
Linear Elastic ◽  
New Phase

A new phase which precipitates from a parent matrix has a size and shape which reflects its difference from parent phase. If the lattice mismatch is significant, the elastic strain energy is more important than the surface energy in determining the morphology and the preferred habit plane. The preferred habit of a tetragonal inclusion in a cubic matrix has been predicted by minimizing the elastic strain energy as from the Ktachaturyan linear elastic formula.

scholarly journals Surface Energy of Au Nanoparticles Depending on Their Size and Shape

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 484 ◽  
Author(s):  
David Holec ◽  
Phillip Dumitraschkewitz ◽  
Dieter Vollath ◽  
Franz Dieter Fischer
Keyword(s):  
Surface Energy ◽  
Surface Area ◽  
Complex Structure ◽  
Characteristic Size ◽  
Bulk Crystals ◽  
Size And Shape ◽  
Nanoparticle Shape ◽  
Universal Power Law ◽  
Atomistic Study ◽  
Surface Facet

Motivated by often contradictory literature reports on the dependence of the surface energy of gold nanoparticles on the variety of its size and shape, we performed an atomistic study combining molecular mechanics and ab initio calculations. We show that, in the case of Au nanocubes, their surface energy converges to the value for ( 0 0 1 ) facets of bulk crystals. A fast convergence to a single valued surface energy is predicted also for nanospheres. However, the value of the surface energy is larger in this case than that of any low-index surface facet of bulk Au crystal. This fact can be explained by the complex structure of the surface with an extensive number of broken bonds due to edge and corner atoms. A similar trend was obtained also for the case of cuboctahedrons. Since the exact surface area of the nanoparticles is an ill-defined quantity, we have introduced the surface-induced excess energy and discuss this quantity as a function of (i) number of atoms forming the nano-object or (ii) characteristic size of the nano-object. In case (i), a universal power-law behaviour was obtained independent of the nanoparticle shape. Importantly, we show that the size-dependence of the surface energy is hugely reduced, if the surface area correction is considered due to its expansion by the electronic cloud, a phenomenon specifically important for small nanoparticles.

Effects of Nanoparticles’ Size and Shape on the Thermodynamic Properties of PI/SiO2 Nanocomposites

NANO ◽  
2020 ◽  
Vol 15 (03) ◽  
pp. 2050041
Author(s):  
Mengfan Liang ◽  
An’ni Yang ◽  
Yan Zhu ◽  
Shuhong Sun
Keyword(s):  
Type System ◽  
Silica Nanoparticle ◽  
Interfacial Area ◽  
Dynamics Simulation ◽  
Spherical Type ◽  
Size Dependency ◽  
Size And Shape ◽  
Filler Size ◽  
Interaction Interface ◽  
Sio2 Nanocomposites

In this paper, the effects of SiO2 size (ranging from 5.7[Formula: see text]Å to 7.50[Formula: see text]Å) and shape (spherical, cylindrical and rod) on the interface structure and the thermodynamic performance of polyimide (PI)/SiO2 composites were investigated by molecular dynamics simulation. Also, whether the nanofiller with isocyanate propyl triethoxysilane (ICTOS) can highly enhance interaction in PI/SiO2 (bonded PI/SiO[Formula: see text] was investigated by experiment. To enhance the interfacial intensity efficiency, the coupling agent ICTOS was used to modify the surface of the silica nanoparticle. The results showed that the size and shape of SiO2 not only affect the interfacial number of hydrogen bonds and the interfacial area, but also impact on the glass transition temperature of the composites. As the radius of the embedded nanosilica increased, the bonded energy and [Formula: see text] gradually decreased, showing a prominent filler size effect. At the same time, the [Formula: see text] of spherical-type system was significantly greater than the nanosystems of other shapes. This is because as the number of surface atoms and superficial area of the spherical filler are higher than the nanofillers of other shapes, the combination between spherical-type silica and the PI chains is more compact than those between cylindrical and rod-like silica and the PI chains. The contributions of different nanofillers to the filler size dependency of [Formula: see text] of the nanocomposites can be elucidated by comparing the interfacial interaction and net structure between the PI matrix and silica which exhibit prominent filler shape and size dependency. Finally, the results were confirmed by the nonbonded interaction energy and reduced radial distribution function (RRDF), and the highly interaction interface is found to bring about a greater reinforcing effect.

scholarly journals Green and Cost-Effective Synthesis of Metallic Nanoparticles by Algae: Safe Methods for Translational Medicine

2020 ◽  
Vol 7 (4) ◽  
pp. 129
Author(s):  
Bushra Uzair ◽  
Ayesha Liaqat ◽  
Haroon Iqbal ◽  
Bouzid Menaa ◽  
Anam Razzaq ◽  
...  
Keyword(s):  
Metallic Nanoparticles ◽  
Molecular Mechanisms ◽  
Cost Effective ◽  
Trisodium Citrate ◽  
Synthesis Methods ◽  
Metallic Ions ◽  
Size And Shape ◽  
Potential Applications ◽  
Spr Effect ◽  
Physical And Chemical

Metal nanoparticles (NPs) have received much attention for potential applications in medicine (mainly in oncology, radiology and infectiology), due to their intriguing chemical, electronical, catalytical, and optical properties such as surface plasmon resonance (SPR) effect. They also offer ease in controlled synthesis and surface modification (e.g., tailored properties conferred by capping/protecting agents including N-, P-, COOH-, SH-containing molecules and polymers such as thiol, disulfide, ammonium, amine, and multidentate carboxylate), which allows (i) tuning their size and shape (e.g., star-shaped and/or branched) (ii) improving their stability, monodispersity, chemical miscibility, and activity, (iii) avoiding their aggregation and oxidation over time, (iv) increasing their yield and purity. The bottom-up approach, where the metal ions are reduced in the NPs grown in the presence of capping ligands, has been widely used compared to the top-down approach. Besides the physical and chemical synthesis methods, the biological method is gaining much consideration. Indeed, several drawbacks have been reported for the synthesis of NPs via physical (e.g., irradiation, ultrasonication) and chemical (e.g., electrochemisty, reduction by chemicals such as trisodium citrate or ascorbic acid) methods (e.g., cost, and/ortoxicity due to use of hazardous solvents, low production rate, use of huge amount of energy). However, (organic or inorganic) eco-friendly NPs synthesis exhibits a sustainable, safe, and economical solution. Thereby, a relatively new trend for fast and valuable NPs synthesis from (live or dead) algae (i.e., microalgae, macroalgae and cyanobacteria) has been observed, especially because of its massive presence on the Earth’s crust and their unique properties (e.g., capacity to accumulate and reduce metallic ions, fast propagation). This article discusses the algal-mediated synthesis methods (either intracellularly or extracellularly) of inorganic NPs with special emphasis on the noblest metals, i.e., silver (Ag)- and gold (Au)-derived NPs. The key factors (e.g., pH, temperature, reaction time) that affect their biosynthesis process, stability, size, and shape are highlighted. Eventually, underlying molecular mechanisms, nanotoxicity and examples of major biomedical applications of these algal-derived NPs are presented.

Obtaining NiHCF Nanoparticles Using a Reverse Micellar System

2010 ◽  
Vol 644 ◽  
pp. 47-50
Author(s):  
Alberto Gutiérrez Becerra ◽  
Tanya Vega Venegas ◽  
Maximiliano Bárcena Soto ◽  
Norberto Casillas ◽  
José Inés Escalante
Keyword(s):  
Particle Size ◽  
Reverse Micelles ◽  
Metallic Nanoparticles ◽  
Reverse Microemulsion ◽  
Ammonium Bromide ◽  
Micellar System ◽  
Nickel Hexacyanoferrate ◽  
Size And Shape ◽  
Reverse Micellar System ◽  
Reverse Micellar

The synthesis of metallic nanoparticles using a reverse microemulsion medium brings controlled size and shape. In this study, reverse micelar system was employed for the synthesis of nickel hexacyanoferrate nanoparticles, NiHCF, by direct encapsulation in the water pools of reverse micelles formed in a pseudoternary system that consist of a mixture of 95 %wt. cetyltrimetyl ammonium bromide (CTAB) and 5 %wt. of a novel modified surfactant cetyltrimetyl ammonium ferrocyanate (CTA[Fe(CN6)]4-, CTAFe)/n-butanol/Hexane/Water. These NiHCF nanoparticles were produced with particle size ranging with 20 – 60 nm.

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