Energy

Researchers from North Carolina State University and the U.S. Department of Energy’s Brookhaven National Laboratory have developed and demonstrated a technique that allows them to engineer a class of materials called layered hybrid perovskites down to the atomic level, which dictates precisely how the materials convert electrical charge into light. Layered hybrid perovskites can be laid down as thin films consisting of multiple sheets of perovskite and organic spacer layers.

Researchers from the University of Virginia, the University of California-Berkeley, the University of Florida, the University of Tennessee-Knoxville, the University of Michigan, and the U.S. Department of Energy’s Sandia National Laboratories and Center for Integrated Nanotechnologies have developed an innovative technique to better determine the nanoscale effects of radiation on materials.

Researchers from the U.S. Department of Energy’s National Renewable Energy Laboratory have developed a trilayer of semiconductors to enable the dissociation of electron-hole pairs, also called excitons – a fundamental process for the performance of photovoltaic systems. The trilayer, which consists of single-walled carbon nanotubes sandwiched between two semiconductors, enables a photo-induced charge transfer cascade, in which electrons move in one direction, while holes move in the other direction.

Researchers from Cornell University have used solubility rather than entropy to overcome thermodynamic constraints and create high-entropy oxide nanocrystals at lower temperatures. High-entropy materials are formed by mixing five or more elements within the structure of a crystal.

Researchers from the University of Michigan, the U.S. Department of Energy’s SLAC National Accelerator Laboratory, Carnegie Mellon University, and Harvard University have discovered that the electrical conductivity of three layers of graphene, in a twisted stack, is similar to that of “magic angle” bilayer graphene. Stacking three layers of graphene introduced an additional twist angle, creating non-repeating patterns, at small-angle twists – unlike bilayer graphene which forms repeating patterns.

Researchers from the U.S. Department of Energy's Argonne National Laboratory and Universidad de Zaragoza in Spain have discovered that how calcite is synthesized, or chemically transformed, can dramatically change the internal structure of individual mineral particles. The scientists compared the external shape and internal structure of calcite particles grown by two synthesis approaches. For one synthesis approach, calcite crystals were grown slowly, and a 3D map of the crystal structure inside the calcite particles showed the orderly, repeating patterns scientists expected to see.

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.

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 from the U.S. Department of Energy’s Lawrence Livermore National Laboratory, Columbia University, and the University of California, Irvine, have discovered a new mechanism that could boost the efficiency of hydrogen production through water splitting. This process relies on hydrated ion-permeable ultrathin coatings (such as porous oxide materials), which are used to select chemical species. Using advanced simulations, the scientists revealed that water confined within nanopores smaller than 0.5 nanometers shows significantly altered reactivity and proton transfer mechanisms.

Imaging the hot turbulence of aircraft propulsion systems may now be possible with sturdy sheets of composite materials that twist light beams, according to researchers from the University of Michigan, the Air Force Research Laboratory, ARCTOS Technology Solutions (Beavercreek, OH), the Brazilian Center for Research in Energy and Materials in Campinas, Brazil, and the Federal University of São Carlos in Brazil. The key is arranging nanomaterials that don't twist light on their own onto layers that turn light waves into either left- or right-handed spirals, known as circular polarizations.