Electro-Orientation of Silver Nanowires in Alternating Fields

Abstract

In this work, we analyze the orientation of silver nanowires immersed in aqueous solutions, under the effect of alternating electric fields in a broad frequency range covering from a few Hz to several MHz. The degree of orientation is experimentally determined by electro-optical techniques, which present the advantage of measuring multiple particles at the same time. In the electro-orientation spectrum, we observe frequency dispersion in the kHz range and provide a theoretical explanation for this behavior: at high frequencies, charge separation in the nanoparticles leads to a large induced dipole responsible for strong orientation. On the other hand, at low frequencies, redistribution of the ions in solution gives rise to an induced double layer that screens the dipolar fields, and as a consequence, the degree of orientation decreases. Moreover, we measure the transient response when the electric field is switched off, from which the size distribution of the polydisperse sample is obtained. The results match those given by electron microscopy determinations.

Light and electric field induced unusual large-scale charge separation in hybrid semiconductor objects

“…for the purpose of functional material synthesis and related topics. [18][19][20][21] In this case, a conducting substrate is placed in a cell filled with electrolyte together with two feeder electrodes, allowing to apply a potential difference. The presence of a potential gradient in the electrolyte will polarize the substrate with respect to the surrounding solution and if this polarization is big enough it will act as a bipolar electrode with two opposite redox reactions (oxidation and reduction) occurring at the polarized extremities.…”

“…The presence of a potential gradient in the electrolyte will polarize the substrate with respect to the surrounding solution and if this polarization is big enough it will act as a bipolar electrode with two opposite redox reactions (oxidation and reduction) occurring at the polarized extremities. 18,20,[22][23][24] This break of symmetry results in the generation of anisotropic Janus objects by a site selective electrodeposition process. However, this concept works best for good conductors, having a lower resistance than the solution, and cannot be applied directly to semiconductors, especially metal oxides, due to their low conductivity.…”

Electro-Orientation and Electro-Rotation of Metallodielectric Janus Particles

“…Solving the EOR problem analytically can be checked against actual JP electro-orientation measurements. A similar method has been also used before to determine the real part of the induced dipole of other particles. ,, …”

“…A similar method has been also used before to determine the real part of the induced dipole of other particles. 11,13,16 The theoretical methodology of the current problem is based on solving the linearized Poisson−Nernst−Planck (PNP) equations and applying the relevant boundary conditions imposed on the two hemispheres, using the "standard" model based on assuming a "weak-field", thin double layer and ignoring surface conductance effects (small Dukhin number). The above approach can be effectively used to explicitly determine both EROT and EOR spectra of a spherical MD-JP.…”

Electric Birefringence of Gold Nanorods: Effect of Surfactant Coating

“…This technique has been successfully used to study dielectric materials, but has only recently been applied to conducting particles in aqueous suspension, namely silver nanowires. ,− In these reports, the authors find that the polarization of metallic particles, and hence their electro-orientation, increases with the frequency of the applied field, contrary to what is observed in the case of insulating particles. This is justified by the induced volume charge, which screens the particle polarization.…”