Graphene-Adsorbate van der Waals bonding memory inspires 'smart' graphene sensors

July 16, 2020

Monolayer graphene, an atomic-layer thick sheet of carbon has found immense applications in diverse fields including chemical sensors, detecting single molecule adsorption events electronically. Therefore, monitoring physisorbed molecule induced changes of the electrical response of graphene has become ubiquitous in graphene based sensors. Electric field tuning of the physisorbed molecule-graphene interaction results in enhanced gas sensing due to unique electric field dependent charge-transfer between the adsorbed gas and graphene. Molecular identification in graphene sensors was predicted based on this unique electrically tunable charge-transfer, which is a signature for different adsorbed molecules. Nevertheless, to achieve molecular identification functionality in graphene sensors, an understanding of the gas adsorption/desorption events and retention of the graphene-gas molecule interaction after turning off the electric field is desired. Until now, the graphene-gas molecule bonding interactions were considered randomized by ambience thermal energy after the electric field is turned off, which is not surprising since these interactions are van der Waals (vdW) bonding and so inherently weak. Nevertheless, this assumed thermal randomization of the graphene-gas molecule vdW bonding was unverified experimentally and a major drawback towards electrically tunable charge-transfer based molecular identification in graphene gas sensors.

To clarify the bonding retention of adsorbed gas molecules on graphene with and without electric field tuning, Osazuwa Gabriel Agbonlahor (current doctoral student), Tomonori Imamura (graduated master's student), Dr. Manoharan Murugananthan (Senior Lecturer), and Professor Hiroshi Mizuta of Mizuta Laboratory at the Japan Advanced Institute of Science and Technology (JAIST) monitored the time-dependent vdW interaction decay of adsorbed CO2 molecules on graphene at different electric fields. Using the electric field to tune the interaction between the adsorbed gas and graphene, the charge-transfer between the adsorbed CO2 molecules and graphene was monitored while the tuning electric field was turned on and after it was turned off. Remarkably, the graphene-gas molecule van der Waals interactions were retained hours after the electric field was turned off, demonstrating both charge-transfer and carrier scattering retention characteristic of the previously applied electric field magnitude and direction i.e. the adsorbed CO2 molecules demonstrated a 'vdW bonding memory'. Due to this bonding memory, the charge-transfer and scattering properties of the adsorbed gas molecules on graphene can be studied hours after the electric field is turned off which is critical for identifying adsorbed molecules based on their signature charge-transfer response to an applied electric field. Furthermore, the long bonding retention time (over 2h) of these electrically tuned adsorbed molecules, sets graphene-based sensors apart as platforms for developing 'smart' sensors suitable for 'beyond-sensing' applications in memory devices and conformational switches.
-end-


Japan Advanced Institute of Science and Technology

Related Graphene Articles from Brightsurf:

How to stack graphene up to four layers
IBS research team reports a novel method to grow multi-layered, single-crystalline graphene with a selected stacking order in a wafer scale.

Graphene-Adsorbate van der Waals bonding memory inspires 'smart' graphene sensors
Electric field modulation of the graphene-adsorbate interaction induces unique van der Waals (vdW) bonding which were previously assumed to be randomized by thermal energy after the electric field is turned off.

Graphene: It is all about the toppings
The way graphene interacts with other materials depends on how these materials are brought into contact with the graphene.

Discovery of graphene switch
Researchers at Japan Advanced Institute of Science and Technology (JAIST) successfully developed the special in-situ transmission electron microscope technique to measure the current-voltage curve of graphene nanoribbon (GNR) with observing the edge structure and found that the electrical conductance of narrow GNRs with a zigzag edge structure abruptly increased above the critical bias voltage, indicating that which they are expected to be applied to switching devices, which are the smallest in the world.

New 'brick' for nanotechnology: Graphene Nanomesh
Researchers at Japan advanced institute of science and technology (JAIST) successfully fabricated suspended graphene nanomesh (GNM) by using the focused helium ion beam technology.

Flatter graphene, faster electrons
Scientists from the Swiss Nanoscience Institute and the Department of Physics at the University of Basel developed a technique to flatten corrugations in graphene layers.

Graphene Flagship publishes handbook of graphene manufacturing
The EU-funded research project Graphene Flagship has published a comprehensive guide explaining how to produce and process graphene and related materials (GRMs).

How to induce magnetism in graphene
Graphene, a two-dimensional structure made of carbon, is a material with excellent mechani-cal, electronic and optical properties.

Graphene: The more you bend it, the softer it gets
New research by engineers at the University of Illinois combines atomic-scale experimentation with computer modeling to determine how much energy it takes to bend multilayer graphene -- a question that has eluded scientists since graphene was first isolated.

How do you know it's perfect graphene?
Scientists at the US Department of Energy's Ames Laboratory have discovered an indicator that reliably demonstrates a sample's high quality, and it was one that was hiding in plain sight for decades.

Read More: Graphene News and Graphene Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.