Graphene News and Discussions

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Don't underestimate undulating graphene: Unique electronics made possible by wavy patterns that channel electrons
https://phys.org/news/2022-03-dont-unde ... nique.html
by Mike Williams, Rice UniversityHenry Yu/Rice University

Lay some graphene down on a wavy surface, and you'll get a guide to one possible future of two-dimensional electronics.

Rice University scientists put forth the idea that growing atom-thick graphene on a gently textured surface creates peaks and valleys in the sheets that turn them into "pseudo-electromagnetic" devices.

The channels create their own minute but detectable magnetic fields. According to a study by materials theorist Boris Yakobson, alumnus Henry Yu and research scientist Alex Kutana at Rice's George R. Brown School of Engineering, these could facilitate nanoscale optical devices like converging lenses or collimators.

Their study appears in the American Chemical Society's Nano Letters.

They also promise a way to achieve a Hall effect — a voltage difference across the strongly conducting graphene —that could facilitate valleytronics applications that manipulate how electrons are trapped in "valleys" in an electronic band structure.

Valleytronics are related to spintronics, in which a device's memory bits are defined by an electron's quantum spin state. But in valleytronics, electrons have degrees of freedom in the multiple momentum states (or valleys) they occupy. These can also be read as bits.

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Graphene gets enhanced by flashing
https://phys.org/news/2022-03-graphene.html
by Mike Williams, Rice University

Flashing graphene into existence from waste was merely a good start. Now Rice University researchers are customizing it.

The Rice lab of chemist James Tour has modified its flash Joule heating process to produce doped graphene that tailors the atom-thick material's structures and electronic states to make them more suitable for optical and electronic nanodevices. The doping process adds other elements to graphene's 2D carbon matrix.

The process reported in the American Chemical Society journal ACS Nano shows how graphene can be doped with a single element or with pairs or trios of elements. The process was demonstrated with single elements boron, nitrogen, oxygen, phosphorus and sulfur, a two-element combination of boron and nitrogen, and a three-element mix of boron, nitrogen and sulfur.

The process takes about one second, is both catalyst- and solvent-free, and is entirely dependent on "flashing" a powder that combines the dopant elements with carbon black.

Doping graphene is possible through bottom-up approaches like chemical vapor deposition or synthetic organic processes, but these usually yield products in trace amounts or produce defects in the graphene. The Rice process is a promising route to produce large quantities of "heteroatom-doped" graphene quickly and without solvents, catalysts or water.
Rice University chemists have created a catalyst- and solvent-free flash Joule heating process for manufacturing b

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In a sea of magic angles, 'twistons' keep electrons flowing through three layers of graphene
https://phys.org/news/2022-04-sea-magic ... trons.html
by Ellen Neff, Columbia University Quantum Initiative

The discovery of superconductivity in two ever-so-slightly twisted layers of graphene made waves a few years ago in the quantum materials community. With just two atom-thin sheets of carbon, researchers had discovered a simple device to study the resistance-free flow of electricity, among other phenomena related to the movement of electrons through a material.

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Researcher uses graphene for same-time, same-position biomolecule isolation and sensing
https://phys.org/news/2022-07-graphene- ... ation.html
by University of Massachusetts Amherst

New research led by University of Massachusetts Amherst assistant professor Jinglei Ping has overcome a major challenge to isolating and detecting molecules at the same time and at the same location in a microdevice. The work, recently published in ACS Nano, demonstrates an important advance in using graphene for electrokinetic biosample processing and analysis, and could allow lab-on-a-chip devices to become smaller and achieve results faster.

The process of detecting biomolecules has been complicated and time-consuming. "We usually first have to isolate them in a complex medium in a device and then send them to another device or another spot in the same device for detection," says Ping, who is in the College of Engineering's Mechanical and Industrial Engineering Department and is also affiliated with the university's Institute of Applied Life Sciences. "Now we can isolate them and detect them at the same microscale spot in a microfluidic device at the same time—no one has ever demonstrated this before."

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Ancient graphene formed 3 billion years before humans discovered it

Graphene, an atom-thick form of carbon, was discovered in 2004 using sticky tape and pencil graphite, but now researchers have found the first ever natural graphene in a gold mine

18 July 2023

Naturally formed graphene has been discovered for the first time, in 3.2-billion-year old rocks underneath a South African gold mine. The find could lead to more energy-efficient ways to produce the material, which has a number of useful electronic properties.

Graphene, a one-atom-thick sheet of carbon, was first discovered in 2004 by scientists using sticky tape to take layers off pencil graphite, but scaling up its production has proved difficult. Current industrial methods to make large quantities of graphene require temperatures exceeding 1000°C (1800°F).

https://www.newscientist.com/article/23 ... overed-it/

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Novel method to construct all-graphene macrostructures
https://phys.org/news/2023-08-method-al ... tures.html
by Li Yuan, Chinese Academy of Sciences

Researchers from Hefei Institutes of Physical Science (HFIPS), Chinese Academy of Sciences (CAS), have proposed a laser-assisted layer-by-layer covalent growth method to prepare highly crystalline all-graphene macrostructures (AGMs). The study was published in Advanced Functional Materials.

Graphene is a two-dimensional carbon material known for its exceptional mechanical, electrical, thermal, and optical properties. To facilitate its large-scale applications, it is crucial to efficiently prepare and assemble graphene at the macroscopic level.

However, conventional methods such as liquid phase self-assembly, 3D printing, and catalytic template techniques can only achieve non-covalent weak interactions between graphene sheets, resulting in discontinuities in the crystal structure. This limitation hampers electrical properties of graphene macrostructures.

In this study, a covalently interconnected AGM with micro-to-macro scalable electrical properties was prepared by lamination of microporous polyethersulfone (PES) membrane. Each stack layer of PES membrane was completely carbonized and seamless interlayer boding was achieved in an air environment using a laser.

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