Contact Potentials, Fermi Level Equilibration, and Surface Charging

Abstract

This article focuses on contact electrification from thermodynamic equilibration of the electrochemical potential of the electrons of two conductors upon contact. The contact potential difference generated in bimetallic macroand nanosystems, the Fermi level after the contact, and the amount and location of the charge transferred from one metal to the other are discussed. The three geometries considered are spheres in contact, Janus particles, and core−shell particles. In addition, the force between the two spheres in contact with each other is calculated and is found to be attractive. A simple electrostatic model for calculating charge distribution and potential profiles in both vacuum and an aqueous electrolyte solution is described. Immersion of these bimetallic systems into an electrolyte solution leads to the formation of an electric double layer at the metal−electrolyte interface. This Fermi level equilibration and the associated charge transfer can at least partly explain experimentally observed different electrocatalytic, catalytic, and optical properties of multimetallic nanosystems in comparison to systems composed of pure metals. For example, the shifts in the surface plasmon resonance peaks in bimetallic core−shell particles seem to result at least partly from contact charging.

Artificial Solid‐Electrolyte Interphase Enabled High‐Capacity and Stable Cycling Potassium Metal Batteries

“…Schematic of the ASEI design and monitoring the interaction between a CNT film and a K foil. This finding is consistent with the studies on contact potential [20] that the difference of work functions of K (≈2.29 eV) and C (5.0 eV) [21] yields an electrochemical potential between the two conductors and thus drives the potassiation of CNT [22] and the reduction of electrolyte. b) Top-view SEM images of pristine CNT film (left) and the CNT film in the K/CNT after contact for 20 h (right).…”

Contact electrification induced interfacial reactions and direct electrochemical nanoimprint lithography in n-type gallium arsenate wafer

“…The machining tolerance is caused by the mobility of positive holes on n-GaAs, which is predicted to be not beyond the Debye length. 46 The results prove that the anodic dissolution of n-GaAs is confined at the Pt/n-GaAs/electrolyte 3-phase interface. The optimization of technical parameters such as imprinting pressure and working temperature are described in the ESI (Fig.…”

Do surfaces of positive electrostatic potential on different halogen derivatives in molecules attract? like attracting like!

“…n), all other geometries are formed due to the attraction between the positive σ‐holes on the halogen atoms of the interacting monomers, providing the answer to the question raised already above. Indeed, these complexes are representative examples that can be used as prototypes for rationalizing the claims of Lekner, and a few others . The F 3 CF•••FCH 3 dimer, conversely, can be understood as a consequence of attraction between the negative (σ‐hole) region on the fluorine in H 3 CF described by the V s,max of −23.19 kcal mol −1 and the positive σ‐hole on the fluorine in FCF 3 described by the V s,max of +1.82 kcal mol −1 .…”

“…However, we focus only on a specific type of attraction between the aforementioned monomers that can be relevant to the question raised and answered by Lekner (see above) . The main aim of this study is thus to show whether the electrostatic model explanation alone, as those provided by Zhao et al, Lekner, and others, can account for the attraction between similarly charged covalently‐bound halogens, especially when the small regions on the halogen atoms of similar but unequal electrostatic potential in different molecules are in close proximity. If they do so, can such an attraction lead to the formation of intermolecular complexes?…”

“…The calculations by Lekner demonstrate that in practice neither wins; the spheres will continue to repel each other . After Lekner published the aforesaid counterintuitive results, there has been an upsurge of scientific interest to understand the underlying phenomena . The possibility of the attraction between likely charged species is also demonstrated experimentally, in which, there are certain types of charged particles that can undergo such a counterintuitive electrostatic interaction, such as assisting in aerosol growth in the atmosphere of Titan …”