scholarly journals Boundary layer friction of solvate ionic liquids as a function of potential

2017 ◽  
Vol 199 ◽  
pp. 311-322 ◽  
Author(s):  
Hua Li ◽  
Mark W. Rutland ◽  
Masayoshi Watanabe ◽  
Rob Atkin
Keyword(s):  
Boundary Layer ◽  
Energy Dissipation ◽  
Pyrolytic Graphite ◽  
Stick Slip ◽  
Friction Forces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Highly Ordered Pyrolytic Graphite ◽  
Cation Layer ◽  
Layer Composition

Atomic force microscopy (AFM) has been used to investigate the potential dependent boundary layer friction at solvate ionic liquid (SIL)–highly ordered pyrolytic graphite (HOPG) and SIL–Au(111) interfaces. Friction trace and retrace loops of lithium tetraglyme bis(trifluoromethylsulfonyl)amide (Li(G4) TFSI) at HOPG present clearer stick-slip events at negative potentials than at positive potentials, indicating that a Li+ cation layer adsorbed to the HOPG lattice at negative potentials which enhances stick-slip events. The boundary layer friction data for Li(G4) TFSI shows that at HOPG, friction forces at all potentials are low. The TFSI− anion rich boundary layer at positive potentials is more lubricating than the Li+ cation rich boundary layer at negative potentials. These results suggest that boundary layers at all potentials are smooth and energy is predominantly dissipated via stick-slip events. In contrast, friction at Au(111) for Li(G4) TFSI is significantly higher at positive potentials than at negative potentials, which is comparable to that at HOPG at the same potential. The similarity of boundary layer friction at negatively charged HOPG and Au(111) surfaces indicates that the boundary layer compositions are similar and rich in Li+ cations for both surfaces at negative potentials. However, at Au(111), the TFSI− rich boundary layer is less lubricating than the Li+ rich boundary layer, which implies that anion reorientations rather than stick-slip events are the predominant energy dissipation pathways. This is confirmed by the boundary friction of Li(G4) NO3 at Au(111), which shows similar friction to Li(G4) TFSI at negative potentials due to the same cation rich boundary layer composition, but even higher friction at positive potentials, due to higher energy dissipation in the NO3− rich boundary layer.

scholarly journals Self-assembly and wetting properties of gold nanorod–CTAB molecules on HOPG

2019 ◽  
Vol 10 ◽  
pp. 696-705 ◽  
Author(s):  
Imtiaz Ahmad ◽  
Floor Derkink ◽  
Tim Boulogne ◽  
Pantelis Bampoulis ◽  
Harold J W Zandvliet ◽  
...  
Keyword(s):  
Self Assembly ◽  
Cetyltrimethylammonium Bromide ◽  
Pyrolytic Graphite ◽  
The Self ◽  
Gold Nanorod ◽  
Force Microscopy ◽  
Wetting Properties ◽  
Atomic Force ◽  
Highly Ordered Pyrolytic Graphite ◽  
Self Assembled

The formation of self-assembled superstructures of cetyltrimethylammonium bromide (CTAB) after drying on a nonwetting highly ordered pyrolytic graphite (HOPG) surface have been investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Although SEM did not reveal coverage of CTAB layers, AFM showed not only CTAB assembly, but also the dynamics of the process on the surface. The self-assembled layers of CTAB molecules on the HOPG terraces prior to nanorod deposition were shown to change the wettability of the surface, and as a result, gold nanorod deposition takes place on nonwetting HOPG terraces.

scholarly journals Nanostructure of [Li(G4)] TFSI and [Li(G4)] NO3solvate ionic liquids at HOPG and Au(111) electrode interfaces as a function of potential

2015 ◽  
Vol 17 (1) ◽  
pp. 325-333 ◽  
Author(s):  
Ben McLean ◽  
Hua Li ◽  
Ryan Stefanovic ◽  
Ross J. Wood ◽  
Grant B. Webber ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Double Layer ◽  
Pyrolytic Graphite ◽  
Force Measurements ◽  
Force Microscopy ◽  
Electrode Surfaces ◽  
Atomic Force ◽  
Highly Ordered Pyrolytic Graphite

Atomic force microscopy (AFM) force measurements have been used to study the solvate ionic liquid (IL) double layer nanostructure at highly ordered pyrolytic graphite (HOPG) and Au(111) electrode surfaces as a function of potential.

Self-assembled phthalocyanine derivatives on highly ordered pyrolytic graphite

2014 ◽  
Vol 18 (08n09) ◽  
pp. 771-777 ◽  
Author(s):  
S. Gokhan Colak ◽  
Mine Ince
Keyword(s):  
Spin Coating ◽  
Pyrolytic Graphite ◽  
Hydroxyl Group ◽  
Supramolecular Organization ◽  
Reference Compound ◽  
Force Microscopy ◽  
Atomic Force ◽  
Highly Ordered Pyrolytic Graphite ◽  
Self Assembled ◽  
Symmetric Derivative

A novel unsymmetrically substituted hydroxy-functionalized Zn ( II ) phthalocyanine (Pc) 1, bearing long aliphatic chains, namely, dodecyloxy units, has been designed and synthesized to investigate the influence of the terminal hydroxyl group on the formation of self-assembled nanostructures. The symmetric derivative, octadodecyloxy- Zn ( II ) Pc (2) has been also synthesized and used as reference compound for comparison purposes. The supramolecular organization of the Pcs has been carried out by spin-coating on a highly ordered pyrolytic graphite (HOPG) surface and has been investigated by atomic force microscopy (AFM) and scanning electron microscopy (STM). AFM and STM studies showed that unsymmetrically substituted hydroxy-functionalized Zn ( II ) Pc 1 gives rise to the formation of wire-like structures in different lengths from nanometer to micrometer scales, whereas in the case of the symmetrical Zn ( II ) Pc 2 the formation of the wires on HOPG was less pronounced.

MOBILITY OF ADSORBED POLYMER CHAINS

2010 ◽  
Vol 83 (4) ◽  
pp. 323-330 ◽  
Author(s):  
D. Goeritz ◽  
R. W. P. Hofmann ◽  
H. H. Bissem
Keyword(s):  
Pyrolytic Graphite ◽  
Polymer Chains ◽  
Glass Layer ◽  
Layer System ◽  
Force Microscopy ◽  
Glass State ◽  
Atomic Force ◽  
Highly Ordered Pyrolytic Graphite ◽  
Adsorbed Polymer ◽  
Thin Polymer

Abstract The behavior of thin polymer films adsorbed on a graphite surface was investigated by means of atomic force microscopy. Via force–distance curves, which were recorded for layers of polyisoprene adsorbed on graphite [highly ordered pyrolytic graphite (HOPG)], a two-layer system was found. The upper layer proved to be soft and not in the glass state. No indications supporting the supposition of an additional glasslike polyisoprene layer underneath this soft layer could be found. Thus, if such a glass layer exists on the HOPG surface, the upper limit of its thickness is set to 3 nm. On the other hand, polystyrene adsorbed on graphite is in the glass state independent of thickness.

In Operando Detection of the Physical Properties Change of the Interfacial Electrolyte during Li-Metal Electrode Reaction by Atomic Force Microscopy

2020 ◽  
Author(s):  
Mitsunori Kitta
Keyword(s):  
Atomic Force Microscopy ◽  
Energy Dissipation ◽  
Physical Properties ◽  
Electrode Surface ◽  
Electrode Reaction ◽  
Metal Electrode ◽  
Ion Concentration ◽  
Force Microscopy ◽  
Atomic Force ◽  
Discharge Reaction

This manuscript propose the operando detection technique of the physical properties change of electrolyte during Li-metal battery operation.The physical properties of electrolyte solution such as viscosity (η) and mass densities (ρ) highly affect the feature of electrochemical Li-metal deposition on the Li-metal electrode surface. Therefore, the operando technique for detection these properties change near the electrode surface is highly needed to investigate the true reaction of Li-metal electrode. Here, this study proved that one of the atomic force microscopy based analysis, energy dissipation analysis of cantilever during force curve motion, was really promising for the direct investigation of that. The solution drag of electrolyte, which is controlled by the physical properties, is directly concern the energy dissipation of cantilever motion. In the experiment, increasing the energy dissipation was really observed during the Li-metal dissolution (discharge) reaction, understanding as the increment of η and ρ of electrolyte via increasing of Li-ion concentration. Further, the dissipation energy change was well synchronized to the charge-discharge reaction of Li-metal electrode.This study is the first report for direct observation of the physical properties change of electrolyte on Li-metal electrode reaction, and proposed technique should be widely interesting to the basic interfacial electrochemistry, fundamental researches of solid-liquid interface, as well as the battery researches.

scholarly journals Dynamic friction energy dissipation and enhanced contrast in high frequency bimodal atomic force microscopy

Friction ◽  
2021 ◽  
Author(s):  
Xinfeng Tan ◽  
Dan Guo ◽  
Jianbin Luo
Keyword(s):  
Atomic Force Microscopy ◽  
Energy Dissipation ◽  
Contact Friction ◽  
Measuring Instruments ◽  
Dynamic Friction ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Friction Energy ◽  
New Applications

AbstractDynamic friction occurs not only between two contact objects sliding against each other, but also between two relative sliding surfaces several nanometres apart. Many emerging micro- and nano-mechanical systems that promise new applications in sensors or information technology may suffer or benefit from noncontact friction. Herein we demonstrate the distance-dependent friction energy dissipation between the tip and the heterogeneous polymers by the bimodal atomic force microscopy (AFM) method driving the second order flexural and the first order torsional vibration simultaneously. The pull-in problem caused by the attractive force is avoided, and the friction dissipation can be imaged near the surface. The friction dissipation coefficient concept is proposed and three different contact states are determined from phase and energy dissipation curves. Image contrast is enhanced in the intermediate setpoint region. The work offers an effective method for directly detecting the friction dissipation and high resolution images, which overcomes the disadvantages of existing methods such as contact mode AFM or other contact friction and wear measuring instruments.

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