Rice University

Researchers at Rice University, together with collaborators from the University of Manchester, the University of Brighton, the South Dakota School of Mines and Technology, the University of Sussex, and Pennsylvania State University, have shown that sub-nanometer-scale wrinkles in graphene can generate a strong electrical polarization simply by bending, without any added chemistry or dopants. The effect, known as flexoelectricity, was predicted theoretically in graphene in 2008 but had not previously been directly measured at this scale.

Flexoelectricity describes polarization induced by a strain gradient, and it can occur even in materials that would otherwise show no polarization at all. In three-dimensional materials, competing electromechanical effects tend to mask it, but atomically thin two-dimensional materials offer a cleaner setting to isolate strain-driven polarization. In principle, bending a two-dimensional sheet tightly enough can perturb the out-of-plane orbitals that carry its electrons, generating a "quantum" flexoelectric response distinct from classical charge separation across a deformed membrane. Confirming this quantum contribution experimentally has been difficult, since most prior work accessed curvatures several orders of magnitude gentler than the atomic-scale bending needed to perturb individual orbitals.

MIT researchers, together with collaborators from Harvard University, Rice University, Yale University, MIT Lincoln Laboratory and Pohang University in South Korea, have developed a technique that uses graphene to grow air-stable, wafer-scale monolayer superconductors, addressing a longstanding barrier to using these ultrathin materials in practical quantum computing hardware.

The superconducting material (yellow/blue) grows in the tiny gap beneath a graphene layer (grey) placed atop a silicon dioxide substrate (purple). The graphene shields it from oxidation while guiding it into a smooth, uniform film over a large area. image credit: MIT

Two-dimensional superconductors are attractive for quantum circuits because their compact size and high crystallinity could enable far smaller quantum devices. However, they degrade almost immediately when exposed to air. Niobium diselenide (NbSe₂), a monolayer superconductor with especially high kinetic inductance - a property that lets it store large amounts of inductive energy in a very small area - has been particularly difficult to work with at scale: researchers have had to rely on small flakes produced by exfoliation, since large-area growth attempts oxidize and degrade before they can be protected.

Rice University researchers from the lab of James Tour have shown that Thomas Edison’s original 1879 carbon-filament light bulbs possibly included a graphene-forming regime, suggesting that one of history’s most iconic inventions may have inadvertently produced turbostratic graphene long before it was formally isolated.

Image from: ACS Nano

Turbostratic graphene can be produced by applying a voltage across a resistant carbon-based material and rapidly heating it to 2,000-3,000 degrees Celsius. In modern terms, that method is called flash Joule heating. But the method available to Edison in 1879 was simply turning on one of his newly patented, stable light bulbs. Unlike modern incandescent light bulbs that rely on tungsten filaments, early versions often used resistant carbon-based filaments like Japanese bamboo. Flipping a switch applied a voltage that rapidly heated the filaments, producing light. Or, perhaps, graphene....

Vacuum is perceived as empty, but in fact it is full of fleeting energy fluctuations - virtual photons popping in and out of existence that can interact with matter, giving rise to new, potentially useful properties. Researchers use optical cavities, structures made of mirrors facing one another, to confine these fluctuations, harnessing their effects to engineer new forms of matter. Conventional optical cavities boost fluctuations, or vacuum fields, for both right- and left-handed circularly polarized light. 

Researchers at Rice University, Harvard University and Max Planck Institute have developed a new cavity design that selectively enhances the quantum vacuum fluctuations of circularly polarized light in a single direction, achieving chirality - a feat that typically requires the use of a strong magnetic field. The team used lightly doped indium antimonide to construct the chiral cavity. The researchers also conducted comprehensive theoretical investigations to predict how the new cavity design would transform the properties of materials placed inside it.

Researchers from Rice University, University of Sussex, Pennsylvania State University and Federal University of Minas Gerais have created a 2D hybrid by chemically integrating two fundamentally different 2D materials - graphene and silica glass - into a single, stable compound called glaphene.

Synthesis and structure of glaphene. Credit: Advanced Materials
 

The team proposed a metastable hybrid structure based on first-principles calculations, synthesized it via scalable liquid precursor-based vapor-phase growth, and chemically validated the interlayer structure and hybridization using extensive optical and electron spectroscopy, mass spectrometry, and atomic-resolution electron microscopy.

Researchers from Rice University and US Army Engineer Research and Development Center have developed an innovative solution to a pressing environmental challenge: removing and destroying per- and polyfluoroalkyl substances (PFAS), commonly called “forever chemicals”. The team's method not only eliminates PFAS from water systems but also transforms waste into graphene

PFAS are synthetic compounds found in various consumer products, valued for their heat, water and oil resistance. However, their chemical stability has made them persistent in the environment, contaminating water supplies and posing significant health risks, including cancer and immune system disruptions. Traditional methods of PFAS disposal are costly, energy-intensive and often generate secondary pollutants, prompting the need for innovative solutions that are more efficient and environmentally friendly.

Advanced Material Development (AMD) has announced the first of its U.S university collaborations as it ramps up plans for a Texas-based Defense and Security business. 

A U.S Army program, managed by AMD’s Chief Science Advisor, Professor Alan Dalton, will now have a significant portion of the project developed at Rice University’s world-renowned Materials Science and Nano Engineering Department which is Chaired by world-leading material scientist Professor Pulickel Ajayan.

Rice University researchers have mapped out how bits of 2D materials move in liquid ⎯ which that could help scientists assemble macroscopic-scale materials with the same useful properties as their 2D counterparts.

In order to maintain these special properties in bulk form, sheets of 2D materials have to be properly aligned ⎯ a process that often occurs in solution phase. The Rice team focused on graphene and hexagonal boron nitride, a material with a similar structure to graphene but composed of boron and nitrogen atoms.

Rice University researchers have found that graphene derived from metallurgical coke, a coal-based product, could serve not only as a reinforcing additive in cement but also as a replacement for sand in concrete.

"This could have a major impact on one of the biggest industries in the world," said James Tour, Rice's T. T. and W. F. Chao Professor and a professor of chemistry, materials science and nanoengineering. "We compared concrete made using the graphene aggregate substitute with concrete made using suitable sand aggregates, and we found our concrete is 25% lighter but just as tough."

Rice University researchers have found a way to harvest hydrogen and graphene from plastic waste using a low-emissions method that could more than pay for itself.

“In this work, we converted waste plastics ⎯ including mixed waste plastics that don’t have to be sorted by type or washed ⎯ into high-yield hydrogen gas and high-value graphene,” said Kevin Wyss, a Rice doctoral alumnus and lead author of the recent study. “If the produced graphene is sold at only 5% of current market value ⎯ a 95% off sale! ⎯ clean hydrogen could be produced for free.”