News from the NNI Community - Research Advances Funded by Agencies Participating in the NNI

Scientists from the U.S. Department of Energy’s Pacific Northwest National Laboratory have discovered that reducing graphene oxide membranes with ultraviolet light alters the oxygen functional groups on the graphene oxide surface. This modification results in a novel separation mechanism that is selective for charge rather than size. Exposure to ultraviolet light selectively removed hydroxyl groups from the graphene oxide planes, leading to enhanced interactions of metal cations with functional groups located at the edges of the graphene oxide. This, in turn, resulted in a lower ratio of free mobile lithium cations in solution compared to calcium cations. 

To function, quantum computers need to be kept very cold – just a few degrees above absolute zero. Now, researchers at Northeastern University, the University of California, Berkeley, the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, and the National Institute for Materials Science in Tsukuba, Japan, have shown that one day, it might be possible to run quantum computers at room temperature. The researchers identified novel van der Waals heterostructures (created by combining layers of atomically thin materials, including graphene) that allow control of the coherent movements of atoms out of their equilibrium positions – also called acoustic phonons – at terahertz frequencies. With current quantum computer transistors, the control of acoustic phonons is limited to the gigahertz range. So, increasing the range of these transistors into terahertz frequencies – an increase by a factor of a thousand – opens the possibility of running quantum computers at room temperature.

Researchers from The University of Texas at El Paso and the Connecticut Agricultural Experiment Station have shown that nanoplastics and per- and polyfluoroalkyl substances (PFAS) – commonly known as forever chemicals – can alter proteins found in human breast milk and infant formulas. While nanoplastics originate primarily from the degradation of larger plastic materials, like water bottles and food packaging, forever chemicals are found in various products, such as cookware and clothing.

Researchers from the U.S. Department of Energy’s SLAC National Accelerator Laboratory and Argonne National Laboratory; Stanford University; Harvard University; Columbia University; Florida State University; and the University of California, Los Angeles, have discovered new behavior in an 50-nanometer-thick two-dimensional material, which offers a promising approach to manipulating light that will be useful for devices that detect, control or emit light, collectively known as optoelectronic devices. Optoelectronic devices are used in light-emitting diodes (LEDs), optical fibers, and medical imaging. The researchers found that when oriented in a specific direction and subjected to linearly polarized terahertz radiation, an ultrathin film of tungsten ditelluride circularly polarizes the incoming light.

Researchers from the U.S. Department of Energy's Princeton Plasma Physics Laboratory and the University of Delaware have provided new insights into the variations that can occur in the atomic structure of two-dimensional materials called transition metal dichalcogenides (TMDs). The researchers found that one of the defects, which involves hydrogen, provides excess electrons. The other type of defect, called a chalcogen vacancy, is a missing atom of oxygen, sulfur, selenium, or tellurium. By shining light on the TMD, the researchers showed unexpected frequencies of light coming from the TMD, which could be explained by the movement of electrons related to the chalcogen vacancy.

Researchers from the University of Illinois Urbana-Champaign have identified how gold nanoparticles transfer charge to a connecting semiconductor and quantified how much charge is transferred using different colors of light. The researchers theorized that by using light to excite collective electronic oscillations (also called a plasmon) in gold nanoparticles, they would get a boost in charge transfer to the semiconductor material. And their study confirmed their theory.

Researchers at Michigan State University have developed a new technique that combines atomic-scale imaging with extremely short laser pulses to detect single-atom defects that manufacturers add to semiconductors to tune their electronic performance. “This is particularly relevant for components with nanoscale structures,” said Tyler Cocker, a scientist who led this study. The technique is straightforward to implement with the right equipment, he added, and his team is already applying it to atomically thin materials, such as graphene nanoribbons.

Researchers from Drexel University, California State University Northridge, and the U.S. Department of Energy’s Lawrence Berkeley National Laboratory have provided the first clear look at the chemical structure of the surface of a two-dimensional (2D) material called titanium carbide MXene. MXenes form a family of 2D materials that have shown promise for water desalination, energy storage, and electromagnetic shielding. "Getting the first atomic-scale look at their surface, using scanning tunneling microscopy, is an exciting development that will open new possibilities for controlling the material surface and enabling applications of MXenes in advanced technologies,” said Yury Gogotsi, the researcher who led this study.

Researchers from The University of Texas at Austin, Baylor University, Penn State, the University of California, Berkeley, the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, and Tohoku University in Japan have developed a way to blast the molecules in plastics and other materials with a laser to break them down into their smallest parts for future reuse. The discovery, which involves laying these materials on top of two-dimensional (2D) materials and then lighting them up, has the potential to improve how we dispose of plastics that are nearly impossible to break down with today's technologies. "By harnessing these unique reactions, we can explore new pathways for transforming environmental pollutants into valuable, reusable chemicals, contributing to the development of a more sustainable and circular economy," said Yuebing Zheng, one of the researchers involved in this study.

Researchers from Purdue University and the University of Illinois Urbana-Champaign have created a process to develop ultrahigh-strength aluminum alloys that are suitable for additive manufacturing. The researchers produced the aluminum alloys by using several transition metals, including cobalt, iron, nickel and titanium. "These intermetallics have crystal structures with low symmetry and are known to be brittle at room temperature," said Anyu Shang, one of the researchers involved in this study. "But our method forms the transitional metal elements into colonies of nanoscale, intermetallics lamellae that aggregate into fine rosettes. The nanolaminated rosettes can largely suppress the brittle nature of intermetallics."