Technical / Research

Researchers from Helmholtz-Zentrum Dresden-Rossendorf, Universität Duisburg-Essen, CENTERA Laboratories, Indian Institute of Technology, University of Maryland and the U.S. Naval Research Laboratory have used graphene disks to demonstrate light-induced transient magnetic fields from a plasmonic circular current with extremely high efficiency. 

The effective magnetic field at the plasmon resonance frequency of the graphene disks (3.5 THz) is evidenced by a strong ( ~ 1°) ultrafast Faraday rotation ( ~ 20 ps). In accordance with reference measurements and simulations, the team estimated the strength of the induced magnetic field to be on the order of 0.7 T under a moderate pump fluence of about 440 nJ cm⁻².

Purdue researchers have examined graphene's thermal properties and found they may not be as revolutionary as previously thought. 

Graphene is often touted as the world's best heat conductor, surpassing diamond - which was previously thought to be able to transfer the most heat the quickest. Diamond’s thermal conductivity is generally understood to be about 2,000 W/(m K). But when scientists started measuring graphene’s thermal conductivity, early estimates reached above 5,000 W/(m K). However, subsequent experimental measurements and modeling have refined graphene’s thermal conductivity and brought the number down to around 3,000, which is still quite better than diamond. The Purdue team focused n this graphene property and found something altogether different.

Researchers at the National University of Singapore (NUS), University of Science and Technology of China and the National Institute for Materials Science in Japan have developed a way to induce and directly quantify spin splitting in two-dimensional materials.

Using this concept, they have experimentally achieved large tunability and a high degree of spin-polarization in graphene. This research achievement can potentially advance the field of two-dimensional (2D) spintronics, with applications for low-power electronics.

Researchers from Peking University, Beijing Normal University and KU Leuven recently reported a novel method to substantially reinforce large-area graphene membranes. Their work provides a facile method to fabricate large-area graphene membranes and paves the road to practical application in the membrane separation field. 

Nanoporous graphene membranes are attractive for molecular separations, but it remains challenging to maintain sufficient mechanical strength during scalable fabrication and module development. In this work, the team drew inspiration from the composite structure of cell membranes and cell walls, and designed a large-area atomically thin nanoporous graphene membrane supported by a fiber-reinforced structure with strong interlamellar adhesion. It was found that factors like fracture stress, fracture strength, and tensile stiffness of the composite membranes can be enhanced compared with other graphene-based membranes of large scale.

Researchers from the University of Hyderabad (UoH) and the Tata Institute of Fundamental Research (TIFR) have developed electrode materials made of Tin antimony alloy based reduced graphene oxide composite which has the potential to enhance energy storage for sodium-ion batteries.

Sodium-ion batteries could offer enhanced energy efficiency, rapid charging capabilities, resilience to extreme temperatures, and safeguards against overheating or thermal runaway incidents. They exhibit reduced toxicity due to their lack of reliance on lithium, cobalt, copper, or nickel, which have the potential to emit environmentally harmful gases in the event of fire, according to a recent official release.

A research team, led by The University of Manchester, have reported a way to use light to accelerate proton transport through graphene, which could advance hydrogen generation technologies.

Proton transport is a key step in many renewable energy technologies, such as hydrogen fuel cells and solar water splitting, and it was also previously shown to be permeable to protons. The recent study has shown that light can be used to accelerate proton transport through graphene, despite the fact that it was previously thought that graphene was impermeable to protons. The researchers found that when graphene is illuminated with light, the electrons in the graphene become excited. These excited electrons then interact with protons, accelerating their transport through the material.

Researchers at Spain's IMDEA Nanoscience, Donostia International Physics Center, Ikerbasque and Poland's University of Opole have developed an analytical method to explain the formation of a quasi-perfect 1D moiré pattern in twisted bilayer graphene. The pattern, naturally occurring in piled 2D materials when a strain force is applied, represents a set of channels for electrons.

The team studied the effects of strain in moiré systems composed of honeycomb lattices. The scientists elucidated the formation of almost perfect one-dimensional moiré patterns in twisted bilayer systems. The formation of such patterns is a consequence of an interplay between twist and strain which gives rise to a collapse of the reciprocal space unit cell. As a criterion for such collapse, they found a simple relation between the two quantities and the material specific Poisson ratio. The induced one-dimensional behavior is characterized by two, usually incommensurate, periodicities.

Researchers at Graphenea, University of Utah and Kairos Sensors have examined a perovskite-based graphene field effect transistor (P-GFET) device for X-ray detection. 

The device architecture consisted of a commercially available GFET-S20 chip, produced by Graphenea, with a layer of methylammonium lead iodide (MAPbI₃) perovskite spin coated onto the top of it. This device was exposed to the field of a molybdenum target X-ray tube with beam settings between 20 and 60 kVp (X-ray tube voltage) and 30–300 μA (X-ray tube current). Dose measurements were taken with an ion-chamber and thermo-luminescent dosimeters and used to determine the sensitivity of the device as a function of the X-ray tube voltage and current, as well as source-drain voltage. 

Researchers at Texas A&M University recently discovered that when charging a supercapacitor, it stores energy and responds by stretching and expanding. This insight could be help design new materials for flexible electronics or other devices that need to be both strong and store energy efficiently.

The team measured stresses that developed in graphene-based supercapacitor electrodes and correlated the stresses to how ions move in and out of the material. For example, when a capacitor is cycled, each electrode stores and releases ions that can cause it to swell and contract. According to the team, this repeated motion can cause the build-up of mechanical stresses, resulting in device failure. To combat this, the research looks to create an instrument that measures mechanical stresses and strains in energy storage materials as they charge and discharge.

A team of scientists, led by David Serrate, CSIC scientist at the Instituto de Nanociencia y Materiales de Aragón, INMA (a joint institute of the CSIC and the University of Zaragoza), has imaged for the first time the magnetic behavior of a graphene nanostructure. The team has not only revealed the magnetic state of narrow graphene ribbons (~2 nm), but has also shown the method they developed to magnetically characterize any planar nanographene.

Starting with a specifically designed organic precursor, the researchers synthesized the ribbons directly onto a magnetic surface, obtaining atomically precise edges that contain an alternating sequence of zig-zag graphene segments. This geometry strongly confines the graphene electron cloud around the edge, which causes the instability responsible for the intrinsic magnetism of the graphene nanostructure –a remarkable fact taking into account that the ribbon is formed just by non-magnetic carbon and hydrogen atoms.