Publications

Stacking Order in Graphite Films Controlled by van der Waals Technology

In graphite crystals, layers of graphene reside in three equivalent, but distinct, stacking positions typically referred to as A, B, and C projections. The order in which the layers are stacked defines the electronic structure of the crystal, providing an exciting degree of freedom which can be exploited for designing graphitic materials with unusual properties including predicted high-temperature superconductivity and ferromagnetism. However, the lack of control of the stacking sequence limits most research to the stable ABA form of graphite. Here we demonstrate a strategy to control the stacking order using van der Waals technology. To this end, we first visualise the distribution of stacking domains in graphite films and then perform directional encapsulation of ABC-rich graphite crystallites with hexagonal boron nitride (hBN). We found that hBN-encapsulation which is introduced parallel to the graphite zigzag edges preserves ABC stacking, while encapsulation along the armchair edges transforms the stacking to ABA. The technique presented here should facilitate new research on the important properties of ABC graphite.

Enhanced CO₂ Hydrogenation to Methanol Using out‐of‐Plane Grown MoS₂ Flakes on Amorphous Carbon Scaffold

The conversion of excess carbon dioxide (CO2) into valuable chemicals is critical for achieving a sustainable society. Among various catalysts, molybdenum disulfide (MoS2) has demonstrated potential for CO2 hydrogenation to methanol. However, its catalytic activity has yet to be fully optimized, and scalable, industrially viable production methods remain underdeveloped. In this work, a chemical vapor deposition (CVD) approach is introduced to grow vertically oriented MoS2 crystals on an amorphous carbon template. This method enhances the exposure of vacancy-rich basal planes, which are crucial for stable catalytic performance. The 2H-MoS2 flakes, supported on a conductive carbon scaffold, exhibit catalytic activity, achieving a net space-time yield of 2.68 gMeOH gcat⁻¹ h⁻¹ with a selectivity of 82.5% under mild conditions (264 °C, 10 bar). This work highlights a significant step toward the industrial application of MoS2-based catalysts for CO2 conversion, bridging the gap between fundamental research and scalable implementation.

Graphene bubbles with controllable curvature

Raised above the substrate and elastically deformed areas of graphene in the form of bubbles are found on different substrates. They come in a variety of shapes, including those which allow strong modification of the electronic properties of graphene. We show that the shape of the bubble can be controlled by an external electric field. This effect can be used to make graphene-based adaptive focus lenses.

Control of Gas Selectivity and Permeability Through Cof-Go Composite Membranes for Sustainable Decarbonization and Hydrogen Production

The most promising way to address modern environmental and energy supply challenges is via rapid implementation of decarbonization and hydrogen production technologies. Development of gas separation membranes with high selectivity and permeability is essential for these processes. Traditional polymeric membranes often struggle to strike the right balance between these properties due to their structural and chemical limitations. Our research focuses on achieving precise control of gas diffusion pathways through on-demand regulation of material interactions in nanometer-thick composite membranes. We combine covalent organic frameworks (COFs) and graphene oxide (GO) to create COF-GO composite membranes. These materials offer enhanced gas separation performance and tailor-made selectivity. By pH-assisted self-assembly, we fine-tune material interactions, achieving a balance between selectivity and permeability by regulating the surface charge density of COF and GO. Our work presents a novel approach to gas separation by manipulating inter-layer interactions between COF and GO, paving the way for tailored gas separation. Through these efforts, we fabricate COF-GO composite membranes with controlled thickness and gas pathways. Compared to bare GO and COF membranes, the composite structure offers an optimal transport performance, enhanced selectivity in thicker membranes without losing permeability, and superior long-term stability. This enables the unique 2D transport mechanism to be utilized under real practical conditions. Our research offers a strategy for the design of composite membranes from two-dimensional (2D) materials for gas separation technologies. It contributes to sustainable decarbonization and hydrogen production solutions, bringing us closer to a greener, more environmentally friendly future.

Condensed Matter Science / High Field Magnet Laboratory (HFML)

No abstract is provided for this article.

Beyond the wonder material

When nature had to choose an element as the basis for life, it chose carbon. If I had to guess why, I would say the reason was carbon's extraordinary versatility. Bonding between carbon atoms is exceptionally strong; indeed, the strongest materials on Earth are all made of carbon. However, bonding between carbon and other elements, though stable, can easily be changed by chemical reactions. The resulting compounds are often surprisingly different from one another. For example, a pair of carbon atoms bonded together can accept one, two or three hydrogen atoms, forming ethyne, ethene and ethane – chemicals used in welding, anaesthesia and vodka-making, respectively.

Multiscale structural and electronic control of molybdenum disulfide foam for highly efficient hydrogen production

Hydrogen production through water splitting has been considered as a green, pure and high-efficient technique. As an important half-reaction involved, hydrogen evolution reaction is a complex electrochemical process involving liquid-solid-gas three-phase interface behaviour. Therefore, new concepts and strategies of material design are needed to smooth each pivotal step. Here we report a multiscale structural and electronic control of molybdenum disulfide foam to synergistically promote the hydrogen evolution process. The optimized three-dimensional molybdenum disulfide foam with uniform mesopores, vertically aligned two-dimensional layers and cobalt atoms doping demonstrated a high hydrogen evolution activity and stability. In addition, density functional theory calculations indicate that molybdenum disulfide with moderate cobalt doping content possesses the optimal activity. This study demonstrates the validity of multiscale control in molybdenum disulfide via overall consideration of the mass transport, and the accessibility, quantity and capability of active sites towards electrocatalytic hydrogen evolution, which may also be extended to other energy-related processes.

Visualization and transport properties of complex graphene moiré superlattices

Milli-Tesla quantization enabled by tuneable Coulomb screening in large-angle twisted graphene

Metamorphism of volcanogenic massive sulphide deposits in the Urals. Ore geology

The Urals VMS province comprises a broad spectrum of variably metamorphosed deposits, from unmetamorphosed to those without any primary ore textures, which are the results of high-grade metamorphic processes. Contact metamorphism near large granite and granodiorite plutons caused the most significant changes of ores, with coarse-grained to pegmatoidal ores with magnetite closest to its contact with the intrusion, followed by pyrrhotite-enriched copper ores, and more distal zinc (±Pb±Ag) mineralisation. Koktau, Tarnyer and Vesenneye deposits are metamorphosed to the hornblende-hornfels and pyroxene-hornfels facies (t =400–800°C, P =1–6kbar). Metamorphism of Tash-Yar, Dzhusinskoe and Krasnogvardeiskoe deposits corresponds to the greenschist and albite-epidote-hornfels facies (t =250–450°C, P =1–4kbar). The regional metamorphism of VMS ores varies from prehnite-pumpellyite facies (t =150–300°C, P =0.5–4kbar) in the South Urals to the epidote-amphibolite and amphibolite facies (t =400–600°C (up to 700°C), P =1–6kbar) in the Karabash area in the Middle Urals. In the Magnitogorsk zone, the metamorphism of host rocks and VMS bodies increases to the north, reaching its peak near the Ufa promontory of the East European platform. With increased metamorphism, the morphology of orebodies evolves from gently dipping thick lenses (Alexandrinskoe and Uzelga fields), to subvertical and folded (Uchaly and Novo-Uchaly deposits) and pseudomonoclinal steeply-dipping vein-like bodies (Karabash district). The massive sulphide transformation in PTX-gradient fields led to partial redistribution of ore material. An enrichment in Cu, Zn, Ag and Au, ±Pb occur in the uppermost parts of large steeply-dipping massive sulphide lenses in wide tectonic zones (e.g., Gai deposit) or as gold-sulphide disseminated bodies near large metamorphosed VMS lenses, distal to a granite pluton (Tarnyer deposit). Partial melting probably occurred in some highly metamorphosed deposits (Tarnyer, Koktau and Mauk). Redeposition of base metals sulphides (chalcopyrite, tennantite, sphalerite, ±bornite, galena), as well as the presence of “visible” gold and tellurides, took place during retrograde metamorphism, which produced a transfer of ore matter towards the low stress areas, such as the outer parts of shear zones, the uppermost parts of steeply-dipping ore lenses, pressure shadows, hinge zones of small folds, and small extension fractures (i.e., Alpine-type veins) in deformed ore body or its immediate surroundings.

<title>Quenching of the hall effect in localised high magnertic field region</title>

We report the suppression of the Hall effect in a mesoscopic Hall cross with a strong magnetic field only in the center and vanishingly small outside. The local magnetic field is produced by placing Dy pillar on top of a structure with high-mobility two-dimensional electron gas (2DEG). The effect is found to be due to a sharp increase of the number of back-scattered and quasi-localized electron orbits. The possibility of localizing electrons inside the magnetic inhomogeneity region is discussed.

Enhanced Self‐Healing in Dual Network Entangled Hydrogels by Macromolecular Architecture and Alignent of Surface Functionalized hBN Nanosheets

Hydrogels have shown great promise as versatile biomaterials for various applications, ranging from tissue engineering to flexible electronics. Among their notable attributes, self‐healing capabilities stand out as a significant advantage, facilitating autonomous repair of mechanical damage and restoration of structural integrity. In this work, a dual network macromolecular biphasic composite is designed using an anisotropic structure which facilitates unidirectional chain diffusion and imparts superior self‐healing and mechanical properties. The resulting nanocomposite demonstrates significantly higher self‐healing efficiency (92%) compared to traditional polyvinyl alcohol (PVA) hydrogels, while also improving the tensile strength and elastic modulus, which typically compete with each other in soft materials. This improvement is attributed to enhanced barrier properties within the matrix due to the alignment of surface‐functionalized 2D hBN nanosheets along the biopolymer scaffold. The insights gained from this research can be leveraged to develop advanced self‐healing materials by using 2D nanofillers as “safety barriers” to define the movement of polymeric chains.

Chlorosulfuric acid-assisted production of functional 2D materials

The use of two-dimensional materials in bulk functional applications requires the ability to fabricate defect-free 2D sheets with large aspect ratios. Despite huge research efforts, current bulk exfoliation methods require a compromise between the quality of the final flakes and their lateral size, restricting the effectiveness of the product. In this work, we describe an intercalation-assisted exfoliation route, which allows the production of high-quality graphene, hexagonal boron nitride, and molybdenum disulfide 2D sheets with average aspect ratios 30 times larger than that obtained via conventional liquid-phase exfoliation. The combination of chlorosulfuric acid intercalation with in situ pyrene sulfonate functionalisation produces a suspension of thin large-area flakes, which are stable in various polar solvents. The described method is simple and requires no special laboratory conditions. We demonstrate that these suspensions can be used for fabrication of laminates and coatings with electrical properties suitable for a number of real-life applications.

Graphene: Electronic Properties

No abstract is provided for this article.

Femtosecond carrier dynamics in bulk graphite and graphene paper

Femtosecond white-light continuum probe transient absorption and reflectivity measurements of bulk graphite and graphene paper are reported. In graphite, the relaxation of photoinduced electron–hole pairs happens through in-plane electron–electron and electron–phonon scattering in ≃200fs, while the ps dynamics is due to the modulation of the electronic structure by out-of-plane structural motions. The ps dynamics of the optical signal is strongly reduced in graphene paper, where the out-of-plane bond is disrupted, while the short component of the dynamics is identical in both materials. These results show that in 2D-graphene, the carrier relaxation occurs in ≃200fs.

Electrically controlled water permeation through graphene oxide membranes

No abstract is provided for this article.

Mind the gap

No abstract is provided for this article.

Performance Improvement by Ozone Treatment of 2D PdSe₂

Atomic-scale defects in two-dimensional transition metal dichalcogenides (TMDs) often dominate their physical and chemical properties. Introducing defects in a controllable manner can tailor properties of TMDs. For example, chalcogen atom defects in TMDs were reported to trigger phase transition, induce ferromagnetism, and drive superconductivity. However, reported strategies to induce chalcogen atom defects including postgrowth annealing, laser irradiation, or plasma usually require high temperature (such as 500 °C) or cause unwanted structural damage. Here, we demonstrate low-temperature (60 °C) partial surface oxidation in 2D PdSe2 with low disorder and good stability. The combination of scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations provide evidence of atomic-scale partial oxidation with both atomic resolution and chemical sensitivity. We also experimentally demonstrate that this controllable oxygen incorporation effectively tailors the electronic, optoelectronic, and catalytic activity of PdSe2. This work provides a pathway toward fine-tuning the physical and chemical properties of 2D TMDs and their applications in nanoelectronics, optoelectronics, and electrocatalysis.