GNRs

Researchers at Nagoya University have synthesized a helical graphene nanoribbon (GNR) whose handedness can be switched on demand. The team built what they call a poly[4]helicene nanoribbon, a ladder-type polymer made entirely of [4]helicene subunits, and showed that dissolving it in a chiral solvent locks the ribbon into a single, uniform spiral direction, right- or left-handed depending on which mirror-image form of the solvent is used.

Helical GNRs have drawn interest as a route to chiral carbon materials for optical and electronic devices, but achieving a controllable, switchable twist has been an unsolved problem. [4]Helicene, a four-ring helicene unit, was considered too configurationally unstable for this purpose, since it flips its own handedness too quickly to hold a fixed twist on its own. The team took the opposite approach: rather than avoiding this instability, they built a long ladder-polymer chain entirely out of [4]helicene units, fusing them together through quantitative intramolecular multifold cyclization of a nonhelical precursor polymer. Because each subunit is mechanically coupled to its neighbors along the rigid, constrained framework, the helicity inversions of adjacent units became correlated, producing long, interconverting sequences of right- (P) and left- (M) handed [4]helicene subunits rather than random, uncorrelated flipping.

University of Arizona researchers have demonstrated that atomically precise graphene nanoribbons (GNRs) can function as highly sensitive gamma-radiation sensors, while maintaining their underlying structural integrity under exposure - an unusual combination that could be valuable for fusion energy systems and space electronics.

In a proof-of-concept study, the team fabricated field-effect transistors (FETs) based on nine-atom-wide armchair graphene nanoribbons (9-AGNRs), synthesized using a bottom-up, on-surface approach. The resulting structures were one atom thick and approximately 45 nanometers long on average, placing them in the quasi-one-dimensional regime where quantum transport effects dominate. These devices were characterized before and after gamma irradiation using Raman spectroscopy and electrical transport measurements.

Researchers from the Max Planck Institute, National Center for Nanoscience and Technology in Beijing, University of Warsaw, TUD Dresden University of Technology, University of Münster, Sichuan University, Friedrich-Alexander-Universität Erlangen-Nürnberg, Empa and Chinese Academy of Science have developed a cyclophane-based molecular shielding strategy that enables the isolation of individual graphene nanoribbons (GNRs) while simultaneously tuning their optoelectronic properties.

Graphene nanoribbons' practical use has long been limited by strong π–π stacking interactions that drive aggregation into bundles, masking intrinsic properties and preventing reliable integration into single-ribbon devices. To address this, the team designed cyclophane-type bridges that sterically shield the GNR backbone while introducing controlled internal strain. Three cyclophane-shielded GNRs (CsGNRs), labeled 1a–c, were synthesized with different tether lengths (benzene–C20–benzene for 1a, C20 for 1b, and C14 for 1c). These structures were derived from ethynyl-substituted cyclopentadienone-based cyclophane monomers, alongside model nanographenes (2a–c) based on a hexa-peri-hexabenzocoronene core.

Researchers from Pohang University of Science and Technology, Griffith University and King Khalid University have developed a graphene-based nanofiltration system that can selectively extract lithium ions from magnesium‑rich brines using sunlight as the driving force. The approach combines edge‑functionalized graphene nanoribbons (GNRs) with photothermally reduced graphene oxide (PrGO), forming sub‑nanometer ion‑coordination channels that enable efficient lithium transport while rejecting competing ions such as magnesium.

Recovering lithium from natural brines is difficult because lithium typically exists at much lower concentrations than other dissolved salts. In South American salt‑flat brines, for example, magnesium concentrations can exceed lithium by ratios of 20:1 or higher. The challenge arises from the similar chemical behavior of the ions, even though their hydration energies differ significantly. Magnesium ions bind water molecules roughly four times more strongly than lithium ions. The new membrane exploits this difference by creating functionalized transport pathways that encourage lithium ions to partially shed their hydration shells and migrate through the membrane while magnesium remains strongly hydrated and effectively blocked.

A recent review by researchers at the Catalan Institute of Nanoscience and Nanotechnology (ICN2) and the Universitu of Barcelona provides an overview of an emerging class of carbon nanomaterials: nanoporous graphenes (NPGs). The work highlights how these structures, conceived as two-dimensional arrays of laterally bonded graphene nanoribbons (GNRs), could transform the future of nanoelectronics and spintronics.

Built through bottom-up on-surface synthesis, this approach enables atomic precision in assembling carbon nanoarchitectures, offering tunable electronic and magnetic properties. While GNRs have long been central to nanoelectronics due to their semiconducting and π-conjugated characteristics, NPGs extend their functionality by providing an intrinsic platform to regulate electronic coupling between adjacent ribbons. This feature allows for the controlled emergence of quantum anisotropy, where electrical conduction varies according to direction.

Researchers from Empa, Chinese Academy of Sciences, the Chinese University of Hong Kong and Max Planck Institute for Polymer Research have developed a hybrid system in which porphyrins are attached to graphene nanoribbons (GNRs) in a precise and well-defined manner. 

Image credit: Credit: Swiss Federal Laboratories for Materials Science and Technology

Graphene nanoribbons with zigzag edges are promising materials for spintronic devices, owing to their tunable bandgaps and spin-polarized edge states. Porphyrins offer complementary optoelectronic benefits. In the new system, a graphene ribbon just one nanometer wide with zigzag edges is used as a molecular wire, along which porphyrin molecules are docked at perfectly regular intervals, alternating between the ribbon’s left and right sides.

Researchers from the National University of Singapore (NUS), working with teams from University of California, Kyoto University and others, have reported a breakthrough in the development of next-generation graphene-based quantum materials, opening new horizons for advancements in quantum electronics.

An atomic model of the Janus graphene nanoribbons (left) and its atomic force microscopic image (right). Image credit: NUS
 

The innovation involves a novel type of graphene nanoribbon (GNR) named Janus GNR (JGNR). The material has a unique zigzag edge, with a special ferromagnetic edge state located on one of the edges. This unique design enables the realization of one-dimensional ferromagnetic spin chain, which could have important applications in quantum electronics and quantum computing.

Van der Waals encapsulation of 2D materials in hBN stacks could be a promising way to create ultrahigh-performance electronic devices. However, current approaches for achieving van der Waals encapsulation, which involve artificial layer stacking using mechanical transfer techniques, are difficult to control, prone to contamination and unscalable. 

Researchers at Shanghai Jiao Tong University, Wuhan University, Ulsan National Institute of Science and Technology, National Institute for Materials Science and Tel Aviv University recently reported the transfer-free direct growth of high-quality graphene nanoribbons (GNRs) in hexagonal boron nitride (hBN) stacks. The as-grown embedded GNRs exhibited highly desirable features being ultralong (up to 0.25 mm), ultranarrow (<5 nm) and homochiral with zigzag edges. 

A team of scientists, led by David Serrate, CSIC scientist at the Instituto de Nanociencia y Materiales de Aragón, INMA (a joint institute of the CSIC and the University of Zaragoza), has imaged for the first time the magnetic behavior of a graphene nanostructure. The team has not only revealed the magnetic state of narrow graphene ribbons (~2 nm), but has also shown the method they developed to magnetically characterize any planar nanographene.

Starting with a specifically designed organic precursor, the researchers synthesized the ribbons directly onto a magnetic surface, obtaining atomically precise edges that contain an alternating sequence of zig-zag graphene segments. This geometry strongly confines the graphene electron cloud around the edge, which causes the instability responsible for the intrinsic magnetism of the graphene nanostructure –a remarkable fact taking into account that the ribbon is formed just by non-magnetic carbon and hydrogen atoms.

Researchers from the University of Illinois at Urbana─Champaign and the University of Nebraska─Lincoln have developed a method for "wiring up" graphene nanoribbons (GNRs). Using a direct-write scanning tunneling microscopy (STM) based process, the nanometer-scale metal contacts were fabricated on individual GNRs and could control the electronic character of the GNRs. 

The team says that this is the first demonstration of making metal contacts to specific GNRs with certainty and that those contacts induce device functionality needed for transistor function.