Band gap

Researchers at India's Cochin University of Science and Technology have developed a bifunctional polyaniline/reduced graphene oxide (PRGO) interlayer integrated into a lithium-sulfur (Li-S) battery separator, demonstrating a practical route to mitigating polysulfide shuttling while improving electrochemical performance.

Li-S systems offer a theoretical specific capacity of 1675 mAh g⁻¹ and energy density approaching 2600 Wh kg⁻¹, but their commercialization has been hindered by sulfur’s extremely low conductivity (~5×10⁻³⁰ S cm⁻¹) and the dissolution and migration of lithium polysulfides (LiPSs). These soluble intermediates form during discharge - initially at 2.1–2.4V (long-chain polysulfides, ~25% of capacity, 418 mAh g⁻¹) and then at 1.6–2.1V (short-chain species, ~75%, 1257 mAh g⁻¹) - and readily diffuse toward the lithium anode, causing active material loss and rapid capacity fading.

Researchers from CSIC-UPV/EHU, the University of the Basque Country (UPV/EHU), the Technical University of Munich, the University of Nebraska–Lincoln, Al-Azhar University, and the Donostia International Physics Center (DIPC) have reported the creation of a previously unrealized two-dimensional (2D) carbon allotrope that integrates graphene’s structure with precisely engineered nanopores and biphenylene segments.

This new material bridges the gap between ideal graphene sheets and more complex, functional carbon architectures, opening promising avenues for next-generation applications in nanoelectronics and chemical sensing.

Researchers from IMDEA Nanociencia, Autonomous University of Madrid and INFN recently announced a breakthrough in the engineering of graphene - they found a way to open a bandgap in the material, that allows the flow of electricity in graphene to be controlled - an essential step for advanced technological applications.

The achievement is based on the controlled intercalation of tellurium (Te) atoms between layers of graphene deposited on an iridium base. Using spectroscopy, microscopy and electron diffraction techniques, the researchers observed that tellurium arranges itself into two different structures, depending on the amount used. Beyond this structure, the modified graphene exhibits an energy gap of up to 240 millielectron volts at room temperature, something the says was never before observed in a stable and adjustable form.

Researchers at the Swiss École Polytechnique Fédérale de Lausanne (EPFL) and National Institute for Materials Science in Japan have developed a new technique to directly measure energy gaps and bandwidths in multilayer graphene systems, paving the way for deeper insights into exotic quantum states and future electronic devices.

When layers of graphene are stacked on top of each other and slightly rotated, the atomic lattices create a periodic interference pattern known as a moiré pattern. This pattern significantly changes the electronic behavior of the material, sometimes leading to exotic quantum phenomena like superconductivity and magnetism. However, directly probing the fine details of these quantum states has been a challenge. Understanding how electrons behave in these stacked graphene systems is crucial for designing future electronic and quantum devices. But conventional techniques struggle to precisely measure energy gaps and bandwidth—the parameters that dictate how electrons move and interact in these systems. Without a reliable method to extract this data, researchers have been piecing together the puzzle through indirect observations.

Researchers at the Georgia Institute of Technology and China's Tianjin University have created a novel functional semiconductor made from graphene, potentially opening the door to various next-gen electronics. 

This discovery comes at a time when silicon, the material from which nearly all modern electronics are made, is reaching its limit in the face of increasingly faster computing and smaller electronic devices. The semiconductor made from graphene is compatible with conventional microelectronics processing methods – a necessity for any viable alternative to silicon.

Researchers from Germany's RWTH Aachen University, Forschungszentrum Jülich and Japan's National Institute for Materials Science (NIMS) have found that bilayer graphene allows the realization of electron–hole double quantum dots that exhibit near-perfect particle–hole symmetry. Moreover, They showed that particle–hole symmetric spin and valley textures lead to a protected single-particle spin-valley blockade that will allow robust spin-to-charge and valley-to-charge conversion, which are essential for the operation of spin and valley qubits.

Quantum dots in semiconductors such as silicon or gallium arsenide are considered great candidates for hosting quantum bits in future quantum processors. The recent study essentially shows that bilayer graphene has even more to offer than other materials. The double quantum dots the researchers have created are characterized by a nearly perfect electron-hole-symmetry that allows a robust read-out mechanism – one of the necessary criteria for quantum computing. 

An international research team, that included researchers from the Harbin Institute of Technology in China, INRS in France and more, has demonstrated a novel process to modify the structure and properties of graphene. This process relied on a chemical reaction known as photocycloaddition, that modifies the bonds between atoms using ultraviolet (UV) light.

"No other material has properties similar to graphene, yet unlike semiconductors used in electronics, it lacks a band gap. In electronics, this gap is a space in which there are no energy levels that can be occupied by electrons. Yet it is essential for interacting with light," explains Professor Federico Rosei of INRS's Énergie Matériaux Télécommunications Research Centre.

A new collaborative study has reported a 17-carbon wide graphene nanoribbon and found that it has the tiniest bandgap observed so far among familiar graphene nanoribbons prepared through a bottom-up approach.

(a) Bottom-up synthesis scheme of 17-AGNR on Au(111), (b) high-resolution STM image, and (c) nc-AFM image of 17-AGNR. Image Credit: Junichi Yamaguchi, Yasunobu Sugimoto, Shintaro Sato, Hiroko Yamada.

The study is part of a project of CREST, JST Japan including Nara Institute of Science and Technology (NAIST), the University of Tokyo, Fujitsu Laboratories and Fujitsu.

A team led by Boston College researchers has used a sheet of graphene to track the electronic signals inherent in biological structures, in order to develop a platform to selectively identify deadly strains of bacteria. This effort could lead to more accurate targeting of infections with appropriate antibiotics, according to the team.

The prototype demonstrates the first selective, rapid, and inexpensive electrical detection of the pathogenic bacterial species Staphylococcus aureus and antibiotic resistant Acinetobacter baumannii on a single platform, said Boston College Professor of Physics Kenneth Burch, a lead co-author of the paper.

This is a sponsored article by Dr Richard Collins, IDTechEx

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