Researchers at the UK's University of Leicester, Russia's Skolkovo Institute of Science and Technology and Kemerovo State University, TerraVox Global in Cyprus, National University of Singapore and the University of Twente in the Netherlands have gained better understanding of superlubricity, where surfaces experience extremely low levels of friction.

The team addressed a longtime mystery in the principles of superlubricity – a state in which two surfaces experience little to almost no friction when sliding across one another. Superlubricity is associated with molecular smooth surfaces such as graphene and has only been observed in a laboratory environment where these surfaces can be synthesized. In various technological applications, this phenomenon could potentially reduce friction up to 1000 – 10000 times, as compared to conventional friction in machines and mechanisms.

Researchers at the University of Sussex and the University of Brighton have presented their recent work on thermoelectric capture, using highly conductive graphene sheets, which aims to improve technologies that capture and convert heat into electricity and tackle the barriers standing before these methods. The aims to advance the possibility of cheap, sustainable technologies for heat capture and conversion – as well as reach a new understanding of how conductivity in graphene-based nanomaterials can be best exploited.

The team assembled nanomaterial networks of varying density and size, from few to many layers of graphene sheets, then measured electrical conductivity as the different arrays were exposed to heat. Their expectation was that the assemblies of larger, thicker sheets would exhibit the highest levels of conductivity but in fact, the opposite outcome was observed, where the smaller, thinner sheets spontaneously formed dense-packed arrays, and performed better than the many-layered samples. 

Researchers at China's Hunan University, Chinese Academy of Sciences and the University of Washington in the U.S have developed a metal-free nanozyme based on graphene quantum dots (GQDs) for highly efficient tumor chemodynamic therapy (CDT).

GQDs have potential as a cost-effective means of addressing the toxicity concerns associated with metal-based nanozymes in tumor CDT. However, the limited catalytic activity of GQDs has posed significant challenges for their clinical application, particularly under challenging catalytic conditions. "The obtained GQDs, which are made from red blood cell membranes, are highly effective in treating tumors with few side effects," said Liu Hongji, a member of the research team. "One of the advantages is that they are metal-free. In addition, they function as excellent peroxidase-like biocatalysts."

Researchers at the University of Hong Kong, National Center for Nanoscience and Technology in Beijing, Harvard University and the University of Stuttgart have advanced the field of molecular sensing by developing a novel method to improve the sensitivity of surface-enhanced infrared absorption (SEIRA). SEIRA uses plasmonic nanostructures to amplify the infrared signals of molecules adsorbed on their surface. Graphene is a particularly promising material for SEIRA because of its high sensitivity and tunability. However, the interaction between graphene and molecules is weakened by intrinsic molecular damping.

The new approach employs synthesized complex-frequency waves (CFW) to amplify the molecular signals detected by graphene-based sensors by at least an order of magnitude. It also applies to molecular sensing in different phases.

Researchers at the University of Bologna have introduced and considered a single layer of brucite Mg(OH)₂, a 2D material that can be easily produced by exfoliation (like graphene from graphite), for the creation of van der Waals composites (known as heterostructures, or heterojunctions), where two monolayers of different materials are stacked and held together by dispersive interactions. 

First principles simulations showed that brucite/graphene composites can modify the electronic properties (position of the Dirac cone with respect to the Fermi level and band gap) according to the crystallographic stacking and the presence of point defects. This could be meaningful for various applications, such as electronics. 

Researchers at Northwestern University, MIT, Harvard University, CIFAR Azrieli Global Scholars Program and Japan's National Institute for Materials Science have developed a graphene-based synaptic transistor capable of higher-level thinking.

The device simultaneously processes and stores information just like the human brain. In new experiments, the researchers demonstrated that the transistor goes beyond simple machine-learning tasks to categorize data and is capable of performing associative learning.

Researchers at North Carolina State University and Pacific Northwest National Laboratory have found that graphene can enhance an important property of metals called the temperature coefficient of resistance. 

They showed that mixing graphene in just the right proportion with copper could lead to improved electrical wires for more efficient electricity distribution to homes and businesses, as well as more efficient motors to power electric vehicles and industrial equipment. The team has applied for a patent for the work, which was supported by the Department of Energy (DOE) Advanced Materials and Manufacturing Technologies Office.

Researchers at the University of Kansas’ Ultrafast Laser Lab have observed the ballistic movement of electrons in graphene in real time. 

Image credit: University of Kansas

“Generally, electron movement is interrupted by collisions with other particles in solids,” said lead author Ryan Scott, a doctoral student in KU’s Department of Physics & Astronomy. “This is similar to someone running in a ballroom full of dancers. These collisions are rather frequent — about 10 to 100 billion times per second. They slow down the electrons, cause energy loss and generate unwanted heat. Without collisions, an electron would move uninterrupted within a solid, similar to cars on a freeway or ballistic missiles through air. We refer to this as ‘ballistic transport.’”

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.