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

Researchers at Rice University have used their flash Joule heating technique to turn plastic into valuable carbon nanotubes and hybrid nanomaterials. The plastic, which does not need to be sorted or washed as in traditional recycling, is “flashed” at temperatures over 3,100 kelvins (about 5,120 degrees Fahrenheit). “Recycling plastic costs more than just producing new plastic,” said Kevin Wyss, a Rice graduate student and lead author of the study. “That's why we turned to upcycling, or turning low-value waste materials into something with a higher monetary or use value.” A lifecycle analysis of the production process revealed that flash Joule heating was considerably more energy-efficient and environmentally friendly than existing nanotube production processes.

Scientists at Rice University have created carbon nanotubes and other hybrid nanomaterials out of plastic waste using an energy-efficient, low-cost, low-emissions process that could also be profitable. "Waste plastic is rarely recycled because it costs a lot of money to do all the washing, sorting, and melting down of the plastics to turn it into a material that can be used by a factory," said Kevin Wyss, the lead author on the study. "We were able to make a hybrid carbon nanomaterial that outperformed both graphene and commercially available carbon nanotubes.”

Physicists from the University of Wisconsin-Madison and the National Institute for Materials Science in Tsukuba, Japan, have directly measured the fluid-like flow of electrons in graphene – an atom-thick sheet of #carbon arranged in a honeycomb pattern – at nanometer resolution for the first time. The researchers used a technique known as scanning tunneling potentiometry (STP) and graphene. They intentionally introduced obstacles in the graphene sheet (spaced at controlled distances) and then applied a current across the sheet. Using STP, they measured the voltage with nanometer resolution at all points on the graphene, producing a two-dimensional map of the electron flow pattern.

Researchers from The Ohio State University, the University of Texas at Dallas, and the National Institute for Materials Science in Tsukuba, Japan, have shown that quantum geometry plays a key role in allowing graphene, when twisted to a precise angle – called the magic angle – to become a superconductor, moving electricity with no loss of energy. In a conventional metal, high-speed electrons are responsible for conductivity. But twisted bilayer graphene has a type of electronic structure in which the electrons move very slowly – in fact, at a speed that approaches zero if the angle is exactly at the magic one. "We can't use the speed of electrons to explain how the twisted bilayer graphene is working," said Marc Bockrath, one of the scientists involved in this study. "Instead, we had to use quantum geometry."

Chemists at Northwestern University have designed a new photonic lattice with properties never before seen in nature. In solid materials, atoms must be equally spaced apart and close enough together to interact effectively. The new architectures are based on stacked lattices of nanoparticles that show interactions across unprecedentedly large distances. Because the nanoparticles can communicate across ultralong distances, the stacked architecture offers potential applications in remote sensing and detection. “This is an entirely new class of engineered materials that have no counterpart or analogue in nature," said Teri Odom, a senior author of the study.

Scientists at the University of Pennsylvania have developed a lipid nanoparticle that can target and deliver messenger RNA (mRNA) to cells in the placenta. Once these cells receive the mRNA, they create vascular endothelial growth factor, a protein that helps expand the blood vessels in the placenta to reduce the mother's blood pressure and restore adequate circulation to the fetus. The researchers' successful trials in mice may lead to promising treatments for preeclampsia in humans. "This treatment would be administered intravenously,” said Kelsey Swingle, the lead author on this study. “That means a pregnant woman would be able to be treated via a simple, non-invasive, and pain-free IV drip."

Despite advancements in cooling solutions, the interface between an electronic chip and its cooling system has remained a barrier for thermal transport due to the materials' intrinsic roughness. Now, researchers from Carnegie Mellon University and the Massachusetts Institute of Technology have built a flexible, powerful, and highly reliable material to efficiently fill the gap. The material is composed of two thin copper films with a graphene-coated copper nanowire array sandwiched in between. The sandwich material consists of a thermal interface material that has twice the thermal conductance of current state-of-the-art thermal interface materials.

Researchers from Florida State University and BNNT Materials (Newport News, VA) have completed the first-ever study on how purified boron nitride nanotubes remain stable in extreme temperatures in inert environments. Boron nitride nanotubes are stronger and more resistant to high temperatures than carbon nanotubes, but manufacturing these materials is challenging. The researchers found that boron nitride nanotubes are fully stable at up to 1,800 degrees Celsius in an inert environment, the chemically inactive atmosphere in which they are manufactured. 

Researchers from Pennsylvania State University and McMaster University in Canada have created two-dimensional oxides, materials with special properties that can serve as an atomically thin insulating layer between layers of electrically conducting materials. The oxides showed good properties for use in stacked materials called heterostructures that can enable electrons to travel vertically through the structure instead of horizontally like conventional electronic devices.

Researchers from the Massachusetts Institute of Technology, the Georgia Institute of Technology, the University of Virginia, Washington University in St. Louis, Sejong University (Seoul, South Korea), Yonsei University (Seoul, South Korea) have developed a new process based on two-dimensional (2D) materials to create light-emitting diode (LED) displays with smaller and thinner pixels. The study shows that the world's thinnest and smallest pixeled displays can be enabled by an active layer separation technology using 2D materials, such as graphene and boron, to enable high array density micro-LEDs.