Related Experiment Video
Updated: Jul 6, 2025
10:28
Probing the Structure and Dynamics of Interfacial Water with Scanning Tunneling Microscopy and Spectroscopy
Published on: May 27, 2018
8.8K
Controllable van der Waals gaps by water adsorption.
Chang Liu1,2, Xuming Zou3, Yawei Lv1
1Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha, China.
Nature Nanotechnology
|January 4, 2024
Summary
Researchers developed a new method to precisely control the height of van der Waals (vdW) gaps using preadsorbed water molecules. This technique allows for fine-tuning of material properties and device performance in two-dimensional (2D) materials.
Area of Science:
- Materials Science
- Surface Science
- Nanotechnology
Background:
- Van der Waals (vdW) gaps at the ångström scale can confine molecules or ions, offering unique ways to tune material properties and investigate microscopic phenomena.
- Precisely controlling the height of vdW gaps between two-dimensional (2D) materials is difficult due to strong vdW interactions.
Purpose of the Study:
- To introduce a general approach for controlling vdW gap height through molecular preadsorption.
- To demonstrate the tunability of vdW gap heights in 2D material systems.
Main Methods:
- Utilizing preadsorption of water molecules on material surfaces to modulate vdW gap height.
- Controlling the saturation vapor pressure of water vapor to precisely manage water molecule adsorption levels.
- Applying the technique to molybdenum disulfide (MoS2) homojunctions to vary vdW gap heights from 5.5 Å to 53.6 Å.
Main Results:
- Demonstrated precise control over vdW gap heights by adjusting water vapor pressure.
- Successfully varied MoS2 homojunction vdW gaps across a significant range (5.5–53.6 Å).
- Showcased the applicability of this method to various homo- and heterojunctions, including 2D artificial superlattices and 2D/3D and 3D/3D heterojunctions.
Conclusions:
- Molecular preadsorption offers a versatile strategy for engineering vdW gaps in diverse material systems.
- Controlled vdW gaps can significantly modulate device performance, as shown by vdW-gap-dependent diode characteristics.
- This technique enhances tunability and variability in vdW material systems, opening new avenues for material design.
Related Concept Videos
01:24Van der Waals Interactions
64.0K
Atoms and molecules interact with each other through intermolecular forces. These electrostatic forces arise from attractive or repulsive interactions between particles with permanent, partial, or temporary charges. The intermolecular forces between neutral atoms and molecules are ion–dipole, dipole–dipole, and dispersion forces, collectively known as van der Waals forces.
64.0K
01:10Van der Waals Equation
4.1K
The ideal gas law is an approximation that works well at high temperatures and low pressures. The van der Waals equation of state (named after the Dutch physicist Johannes van der Waals, 1837−1923) improves it by considering two factors.
First, the attractive forces between molecules, which are stronger at higher densities and reduce the pressure, are considered by adding to the pressure a term equal to the square of the molar density multiplied by a positive coefficient a. Second, the volume...
First, the attractive forces between molecules, which are stronger at higher densities and reduce the pressure, are considered by adding to the pressure a term equal to the square of the molar density multiplied by a positive coefficient a. Second, the volume...
4.1K
02:56Intermolecular Forces and Physical Properties
20.8K
20.8K
04:01Real Gases: Effects of Intermolecular Forces and Molecular Volume Deriving Van der Waals Equation
34.6K
Thus far, the ideal gas law, PV = nRT, has been applied to a variety of different types of problems, ranging from reaction stoichiometry and empirical and molecular formula problems to determining the density and molar mass of a gas. However, the behavior of a gas is often non-ideal, meaning that the observed relationships between its pressure, volume, and temperature are not accurately described by the gas laws.
34.6K
03:13Intermolecular Forces
58.4K
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen...
58.4K
01:07Cohesion
54.3K
Cohesion is the attraction between molecules of the same type, such as water molecules. Water molecules have an overall neutral charge but are polar molecule. An oxygen atom in one water molecule has a partial negative charge that can bind to a hydrogen atom with a partial positive charge in a second water molecule, forming a hydrogen bond. Each water molecule can form up to four hydrogen bonds with other water molecules. Hydrogen bonds are responsible for water's cohesive nature.
On a...
On a...
54.3K