Related Experiment Video
Updated: May 15, 2026
11:42
Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
Free energy relationships in the electrical double layer over single-layer graphene
Jennifer L Achtyl1, Ivan V Vlassiouk, Pasquale F Fulvio
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
Journal of the American Chemical Society
|January 10, 2013
Summary
Single-layer graphene significantly reduces interfacial free energy at the fused silica/water interface by up to sevenfold. This finding is crucial for understanding interfacial processes in chemistry and materials science under flow conditions.
Area of Science:
- Materials Science
- Physical Chemistry
- Surface Science
Background:
- Fluid/solid interfaces with single-layer graphene are critical in various scientific disciplines.
- Experimental investigation of these interfaces, especially under flow and without labels, presents significant challenges.
Purpose of the Study:
- To quantify the interfacial free energy at the fused silica/single-layer graphene/water interface.
- To investigate the effect of flowing aqueous electrolyte solutions on this interface.
Main Methods:
- Utilized second harmonic generation (SHG) for label-free quantification.
- Studied interfaces under flowing aqueous electrolyte solutions with varying NaCl concentrations (10^-4 to 10^-1 M) at pH 7.
Main Results:
- Single-layer graphene was found to reduce the interfacial free energy density of the fused silica/water interface by a factor of up to 7.
- This reduction is substantial and impacts interfacial processes, including electrochemical ones.
Conclusions:
- Second harmonic generation provides a viable method for studying interfacial properties of graphene-based systems under flow.
- The significant reduction in interfacial free energy by graphene has broad implications for controlling interfacial phenomena in diverse applications.
Related Concept Videos
01:30The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...
01:16Electric Field of Parallel Conducting Plates
Gauss' law relates the electric flux through a closed surface to the net charge enclosed by that surface. Gauss's law can be applied to find the electric field and the charge enclosed in a region depending on its charge distribution.
Consider a cross-section of a thin, infinite conducting plate having a positive charge. For such a large thin plate, as the thickness of the plate tends to zero, the positive charges lie on the plate's two large faces. Without an external electric field, the...
Consider a cross-section of a thin, infinite conducting plate having a positive charge. For such a large thin plate, as the thickness of the plate tends to zero, the positive charges lie on the plate's two large faces. Without an external electric field, the...
01:16Electrostatic Boundary Conditions
Consider an external electric field propagating through a homogeneous medium. When the electric field crosses the surface boundary of the medium, it undergoes a discontinuity. The electric field can be resolved into normal and tangential components. The amount by which the field changes at any boundary is given by the difference between the field components above and below the surface boundary.
The surface integral of an electric field is given by Gauss's law in integral form and is related to...
The surface integral of an electric field is given by Gauss's law in integral form and is related to...
02:56Free Energy and Equilibrium
The free energy change for a process may be viewed as a measure of its driving force. A negative value for ΔG represents a driving force for the process in the forward direction, while a positive value represents a driving force for the process in the reverse direction. When ΔGrxn is zero, the forward and reverse driving forces are equal, and the process occurs in both directions at the same rate (the system is at equilibrium).
Recall that Q is the numerical value of the mass action expression...
Recall that Q is the numerical value of the mass action expression...
00:55Free Energy and Equilibrium
The free energy change for a process may be viewed as a measure of its driving force. A negative value for ΔG represents a driving force for the process in the forward direction, while a positive value represents a driving force for the process in the reverse direction. When ΔG is zero, the forward and reverse driving forces are equal, and the process occurs in both directions at the same rate (the system is at equilibrium).
The reaction quotient, Q, is a convenient measure of the status of an...
The reaction quotient, Q, is a convenient measure of the status of an...
01:21Energy Associated With a Charge Distribution
The work done to bring a charge through a distance r is given by the potential difference between the initial and the final position. To assemble a collection of point charges, the total work done can be expressed in terms of the product of each pair of charges divided by their separation distance, defined with respect to a suitable origin. Solving this expression gives the energy stored in a point charge distribution.