Publications

Gold and silver mineralogy is studied in ores of the Biksizak base-metal deposit (South Urals, Russia). This is a skarn-related carbonate replacement mineralization typical for marginal zones of porphyry-epithermal systems. The variability of precious metals minerals is established. Native gold (fineness 853 to 939) in assemblage with chalcopyrite and sphalerite is the most abundant. A telluride assemblage (tetradymite, hessite, stützite, petzite, galena, tellurobismuthite, rucklidgeite, altaite and native gold with a fineness of 830–900) and a silver–pearceite–acanthite assemblage (acanthite/argentite, pearceite–polybasite and gold–silver alloy from native gold with fineness of 747 to native silver) are identified. It is shown the exhibited variability is controlled by decreasing the temperature and variations in the tellurium and sulfur fugacities.

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.

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.

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.

Graphene/hBN/graphene tunnel devices offer promise as sensitive mid-infrared photodetectors but the microscopic origin underlying the photoresponse in them remains elusive. In this work, we investigated the photocurrent generation in graphene/hBN/graphene tunnel structures with localized defect states under mid-IR illumination. We demonstrate that the photocurrent in these devices is proportional to the second derivative of the tunnel current with respect to the bias voltage, peaking during tunneling through the hBN impurity level. We revealed that the origin of the photocurrent generation lies in the change of the tunneling probability upon radiation-induced electron heating in graphene layers, in agreement with the theoretical model that we developed. Finally, we show that at a finite bias voltage, the photocurrent is proportional to either of the graphene layers heating under the illumination, while at zero bias, it is proportional to the heating difference. Thus, the photocurrent in such devices can be used for accurate measurements of the electronic temperature, providing a convenient alternative to Johnson noise thermometry.

2D hexagonal boron nitride (hBN) is a wide-bandgap van der Waals crystal with a unique combination of properties, including exceptional strength, large oxidation resistance at high temperatures, and optical functionalities. Furthermore, in recent years hBN crystals have become the material of choice for encapsulating other 2D crystals in a variety of technological applications, from optoelectronic and tunneling devices to composites. Monolayer hBN, which has no center of symmetry, is predicted to exhibit piezoelectric properties, yet experimental evidence is lacking. Here, by using electrostatic force microscopy, this effect is observed as a strain-induced change in the local electric field around bubbles and creases, in agreement with theoretical calculations. No piezoelectricity is found in bilayer and bulk hBN, where the center of symmetry is restored. These results add piezoelectricity to the known properties of monolayer hBN, which makes it a desirable candidate for novel electromechanical and stretchable optoelectronic devices, and pave a way to control the local electric field and carrier concentration in van der Waals heterostructures via strain. The experimental approach used here also shows a way to investigate the piezoelectric properties of other materials on the nanoscale by using electrostatic scanning probe techniques.

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.

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.

Dataset and codes for the manuscript "Topological engineering of terahertz light using electrically tuneable exceptional point singularities".

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.