scholarly journals Metal Nanoparticles as Free-Floating Electrodes

Encyclopedia ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 551-565
Author(s):  
Johann Michael Köhler ◽  
Jonas Jakobus Kluitmann ◽  
Peter Mike Günther
Keyword(s):  
Metal Nanoparticles ◽  
Particle Interaction ◽  
Particle Growth ◽  
Metal Electrodes ◽  
Molecular Systems ◽  
Electrochemically Active ◽  
Assembly Behavior ◽  
Shell Particles ◽  
Electrically Charged ◽  
Electrode Systems

Colloidal metal nanoparticles in an electrolyte environment are not only electrically charged but also electrochemically active objects. They have the typical character of metal electrodes with ongoing charge transfer processes on the metal/liquid interface. This picture is valid for the equilibrium state and also during the formation, growth, aggregation or dissolution of nanoparticles. This behavior can be understood in analogy to macroscopic mixed-electrode systems with a free-floating potential, which is determined by the competition between anodic and cathodic partial processes. In contrast to macroscopic electrodes, the small size of nanoparticles is responsible for significant effects of low numbers of elementary charges and for self-polarization effects as they are known from molecular systems, for example. The electrical properties of nanoparticles can be estimated by basic electrochemical equations. Reconsidering these fundamentals, the assembly behavior, the formation of nonspherical assemblies of nanoparticles and the growth and the corrosion behavior of metal nanoparticles, as well as the formation of core/shell particles, branched structures and particle networks, can be understood. The consequences of electrochemical behavior, charging and self-polarization for particle growth, shape formation and particle/particle interaction are discussed.

scholarly journals The Mixed-Electrode Concept for Understanding Growth and Aggregation Behavior of Metal Nanoparticles in Colloidal Solution

2018 ◽  
Vol 8 (8) ◽  
pp. 1343
Author(s):  
Johann Köhler ◽  
Andrea Knauer
Keyword(s):  
Metal Nanoparticles ◽  
Colloidal Solution ◽  
Particle Growth ◽  
Open Circuit ◽  
Aggregation Behavior ◽  
Nanoparticle Growth ◽  
Aspect Ratios ◽  
Spherical Metal Nanoparticles ◽  
High Yields ◽  
And Behavior

The growth and aggregation behavior of metal nanoparticles can be modulated by surfactants and different other additives. Here the concept of how open-circuit mixed electrodes helps to understand the electrical aspects of nanoparticle growth and the consequences for the particle geometries is discussed. A key issue is the self-polarization effect of non-spherical metal nanoparticles, which causes a local decoupling of anodic and partial processes and asymmetry in the local rates of metal deposition. These asymmetries can contribute to deciding to the growth of particles with high aspect ratios. The interpretation of electrochemical reasons for particle growth and behavior is supported by experimental results of nanoparticle syntheses supported by microfluidics which can supply high yields of non-spherical nanoparticles and colloidal product solutions of high homogeneity.

Controllable assembly of two types of metal nanoparticles onto block copolymer nanospheres with ordered spatial distribution

2015 ◽  
Vol 3 (7) ◽  
pp. 3382-3389 ◽  
Author(s):  
Shilin Mei ◽  
Jie Cao ◽  
Yan Lu
Keyword(s):  
Spatial Distribution ◽  
Block Copolymer ◽  
Metal Nanoparticles ◽  
Catalytic Properties ◽  
Reduction Process ◽  
Template Method ◽  
Core Shell ◽  
Aao Template ◽  
Shell Particles

Pd@PS-P2VP @DT–Au core–shell particles are fabricated based on the modified AAO template method and anin situreduction process, showing efficient optical and catalytic properties.

scholarly journals Plasticized PVC Membrane Modified Electrodes: Voltammetry of Highly Hydrophobic Compounds

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 202 ◽  
Author(s):  
Ernő Lindner ◽  
Marcin Guzinski ◽  
Bradford Pendley ◽  
Edward Chaum
Keyword(s):  
Chemical Sensor ◽  
Modified Electrodes ◽  
Pvc Membrane ◽  
Plasticized Pvc ◽  
Hydrophobic Compounds ◽  
Voltammetric Measurement ◽  
Electrochemically Active ◽  
Highly Hydrophobic ◽  
Electrically Charged ◽  
Voltammetric Measurements

In the last 50 years, plasticized polyvinyl chloride (PVC) membranes have gained unique importance in chemical sensor development. Originally, these membranes separated two solutions in conventional ion-selective electrodes. Later, the same membranes were applied over a variety of supporting electrodes and used in both potentiometric and voltammetric measurements of ions and electrically charged molecules. The focus of this paper is to demonstrate the utility of the plasticized PVC membrane modified working electrode for the voltammetric measurement of highly lipophilic molecules. The plasticized PVC membrane prevents electrode fouling, extends the detection limit of the voltammetric methods to sub-micromolar concentrations, and minimizes interference by electrochemically active hydrophilic analytes.

scholarly journals Preparation, Properties, and Self-Assembly Behavior of PTFE-Based Core-Shell Nanospheres

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Katia Sparnacci ◽  
Diego Antonioli ◽  
Simone Deregibus ◽  
Michele Laus ◽  
Giampaolo Zuccheri ◽  
...  
Keyword(s):  
Particle Size ◽  
Self Assembly ◽  
Colloidal Crystal ◽  
Colloidal Crystals ◽  
Direct Consequence ◽  
Core Shell ◽  
Precise Control ◽  
Assembly Behavior ◽  
Shell Particles ◽  
High Degree

Nanosized PTFE-based core-shell particles can be prepared by emulsifier-free seed emulsion polymerization technique starting from spherical or rod-like PTFE seeds of different size. The shell can be constituted by the relatively high Tg polystyrene and polymethylmethacrylate as well as by low Tg polyacrylic copolymers. Peculiar thermal behavior of the PTFE component is observed due to the high degree of PTFE compartmentalization. A very precise control over the particle size can be exerted by properly adjusting the ratio between the monomers and the PTFE seed. In addition, the particle size distribution self-sharpens as the ratio monomer/PTFE increases. Samples with uniformity ratios suited to build 2D and 3D colloidal crystals are easily prepared. In particular, 2D colloidal crystal of spheres leads to very small 2D nanostructuration, useful for the preparation of masks with a combination of nanosphere lithography and reactive ion etching. 3D colloidal crystals were also obtained featuring excellent opal quality, which is a direct consequence of the monodispersity of colloids used for their growth.

scholarly journals Growth kinetics of metal nanoparticles on solid surfaces

2014 ◽  
Vol 70 (a1) ◽  
pp. C1176-C1176
Author(s):  
Ezzeldin Metwalli
Keyword(s):  
Block Copolymer ◽  
Metal Nanoparticles ◽  
Growth Kinetics ◽  
Particle Growth ◽  
Polymer Surfaces ◽  
Particle Mobility ◽  
Metal Interactions ◽  
Metal Metal ◽  
Kinetics Of

Dispersed metal nanoparticles (nps) in a polymer matrix are essential for many technological applications, including biological imaging, thin film technology, magnetic recording media, optoelectronics and sensors. Real time investigation of the evolution of nps size and shape during the in-situ metal deposition on polymer thin films enables a fine tune of magnetic and electric properties. Metals in their atomic state are deposited on several homopolymer and block copolymer films by DC magnetron system (Metwalli et al., 2013, Metwalli et al., 2008, Buffet et al., 2011). With the unprecedented time resolution of 10 milliseconds, the growth kinetics of the metal nps on the polymer surfaces is monitored using in-situ GISAXS. An exponential growth of nps size on all polymer surfaces is observed. Below a certain critical nps size, an initial fast particle growth is due to high particle mobility. A slower kinetics at concentrated metal dispersion is due to the strong metal-metal interactions. The metal growth kinetics study for many chemically different homopolymer films explains the long-time debated high selectivity characteristics of metals towards one block in block copolymer based nano-templates.

scholarly journals Formation of Star-Like and Core-Shell AuAg Nanoparticles during Two- and Three-Step Preparation in Batch and in Microfluidic Systems

2007 ◽  
Vol 2007 ◽  
pp. 1-7 ◽  
Author(s):  
J. Michael Köhler ◽  
H. Romanus ◽  
U. Hübner ◽  
J. Wagner
Keyword(s):  
Early Stage ◽  
Silver Ions ◽  
Particle Growth ◽  
Core Shell ◽  
Time Interval ◽  
Silver Deposition ◽  
Shell Nanoparticles ◽  
Spherical Core ◽  
Flow Through ◽  
Shell Particles

Regular dendrit-like metal nanoparticles and core-shell nanoparticles were formed by the reduction of mixtures of tetrachloroaurate and silver nitrate solutions with ascorbic acid at room temperature in two- and three-step procedures. The formation of these particles was found in batch experiments as well as in micro flow-through processes using static micromixers. The characteristic diameters of 4-branched star particles were in the range between 60 and 100 nm. The typical particles consist of four metal cores which are embedded in a common shell. Additionally, particles with five and more metallic cores were formed, to some extent, and aggregates of the 4-branched particles also were formed. Larger aggregates and network-like structures of connected star particles were formed after sedimentation. The properties of the formed particles are dependent on the educt concentrations as well as on the order of mixing steps and on the time interval between them. Obviously, the relation of nucleation and particle growth in relation to the concentrations of metal ions determines the composition and the properties of formed nanoparticles. So, star-like particles are observed in case of nucleation of Au in absence of silver ions but with silver deposition after short nucleation time. Spherical core shell particles are formed in case of silver salt addition after complete reduction of tetrachloroaurate in flow-through experiments with sufficient residence time between both mixing steps. Polymer layers are always found in the form of a second outer shell even if the polymer solutions are added in an early stage of particle formation.

Organic Thin Film Transistors with Contacts Printed from Metal Nanoparticles

2005 ◽  
Vol 871 ◽  
Author(s):  
Yiliang Wu ◽  
Yuning Li ◽  
Sandra Gardner ◽  
Beng S. Ong
Keyword(s):  
Thin Film ◽  
Metal Nanoparticles ◽  
Thin Film Transistors ◽  
Electronic Device ◽  
Organic Thin Film Transistors ◽  
Organic Thin Film ◽  
Metal Electrodes ◽  
Gold And Silver Nanoparticles ◽  
Stencil Printing ◽  
Device Applications

AbstractMetal nanoparticles were studied as solution printable precursors to highly conductive elements for electronic device applications. Dispersions of gold and silver nanoparticles stabilized respectively with butanethiol and hexadecylamine in organic solvents were used to prepare electrode features for organic thin film transistors (OTFTs) via stencil printing. The printed features, annealed at a relatively low temperature of 140-160°C, yielded metal electrodes with conductivities resembling those of vacuum-evaporated pure metals. The OTFTs with the source and drain electrodes of this nature exhibited field effect transistor performance identical to those of devices having vacuum-evaporated metal electrodes.

scholarly journals Conducting materials as building blocks for electronic textiles

MRS Bulletin ◽  
2021 ◽  
Author(s):  
Anja Lund ◽  
Yunyun Wu ◽  
Benji Fenech-Salerno ◽  
Felice Torrisi ◽  
Tricia Breen Carmichael ◽  
...  
Keyword(s):  
Conducting Polymers ◽  
2D Materials ◽  
Building Blocks ◽  
Elastic Fibers ◽  
Electronic Textiles ◽  
Metal Electrodes ◽  
Active Materials ◽  
Textile Materials ◽  
Conducting Materials ◽  
Electrochemically Active

Abstract To realize the full gamut of functions that are envisaged for electronic textiles (e-textiles) a range of semiconducting, conducting and electrochemically active materials are needed. This article will discuss how metals, conducting polymers, carbon nanotubes, and two-dimensional (2D) materials, including graphene and MXenes, can be used in concert to create e-textile materials, from fibers and yarns to patterned fabrics. Many of the most promising architectures utilize several classes of materials (e.g., elastic fibers composed of a conducting material and a stretchable polymer, or textile devices constructed with conducting polymers or 2D materials and metal electrodes). While an increasing number of materials and devices display a promising degree of wash and wear resistance, sustainability aspects of e-textiles will require greater attention. Graphical abstract

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