Alexander N. Grigorenko

Creating direct pathways that transform dissolved metal waste into functional architecture is central to sustainable nanomanufacturing and circular materials design. Here, we report a redox-driven strategy for the direct conversion of gold (Au) ions from electronic waste into spatially organized Au/MXene nanoarchitectures and electrocatalytic membranes. Ti3C2Tx MXene nanosheets exhibit an Au uptake capacity of 3720 mg g–1 at 1 ppm, together with high selectivity in the presence of excess competing metal ions. Mechanistic studies reveal that the Au capture is coupled with spontaneous interfacial redox conversion, where ∼91% of Au(III) ions are reduced in situ into metallic Au nanoparticles on the MXene surface. Importantly, performing the recovery process in a dispersed colloidal state enables recovery-induced interlayer assembly, producing homogeneous Au distributions throughout the MXene framework after vacuum-assisted membrane formation. In contrast to surface-confined deposition in conventional filtration architectures, the interlayer nanoarchitecture preserves ion-transport pathways and maximizes catalytic accessibility. We further show that ultratrace Au concentrations promote the formation of highly dispersed confined Au domains, enabling efficient electrocatalytic membranes despite substantially lower gold loading. The resulting membranes function directly as flexible binder-free electrodes without additional refining, metal stripping, or catalyst deposition steps. This work establishes a recovery-as-fabrication strategy in which dissolved metal ions are directly transformed into functional nanoarchitectures through coupled redox reduction, confined nucleation, and interlayer assembly.

Photocatalytic water splitting by semiconductors is elucidated in many important works. At the same time, mechanisms of plasmonic enhancement of photocatalytic water splitting by metals are still debated. Here, we study hybrid photocatalysts in which a main metallic catalyst, AlB ₂ , is combined with a co‐catalyst made of either a metal, a semiconductor or a dielectric (FeSe, WS ₂ and ZrO ₂ ). These catalysts are fabricated from AlB ₂ and relevant powders by a low‐cost, high‐yield and scalable rolling mill technique. They demonstrate photocatalytic water/seawater splitting under solar‐like radiation with high efficiency. We show that the reasons for efficiency enhancement are connected to optical impedance matching in hybrid photoanodes, reasonable light absorption that allowed total light absorption in 300 nm films, and matching the absorption spectrum of photoanodes to the spectrum of solar light. Using hybrid photoanodes composed of AlB ₂ and FeSe nanostructures, we achieved a maximum applied bias photon‐to‐current efficiency of ∼10% under simulated solar illumination with an applied bias of 0.3 V, which brings our approach within values for the commercial viability benchmark. We also demonstrate seawater splitting using stable AlB ₂ ‐FeSe and AlB ₂ ‐WS ₂ photoanodes attaining current densities of ∼5 mA/cm ² by solar illumination raising efficiency of seawater splitting to ∼5%. Bifunctionality of studied hybrid photoanodes is established.

Thick-walled cylindrical shell structures are essential components of various modern engineering systems, including pipelines, storage tanks, reactor installations, and aerospace bodies. The operation of such structures under complex mechanical or thermal loading requires reliable analysis of their stress–strain state, particularly in the presence of distributed loads varying along the circumferential direction. Such effects may arise from non-uniform working medium pressure, for example, asymmetric turbulent flow in pipelines or asymmetric aerodynamic loads acting on aerospace hulls. These factors can significantly influence the strength, stability, and service life of the structures. This study presents a three-dimensional approach to the analysis of the stress–strain state of an anisotropic thick-walled cylindrical boroplastic shell subjected to distributed pressure periodically varying in the circumferential direction. The anisotropy of the elastic properties of the material is determined by the misalignment of its orthotropy axes with the curvilinear coordinate system of the cylindrical shell. To derive the three-dimensional system of differential equations, a modification of the Hu – Washizu variational principle is applied. The resulting system is solved using the analytical Bubnov – Galerkin method. Within this framework, all stress–strain components are expanded into double Fourier series, ensuring that the longitudinal coordinate satisfies boundary conditions at the shell ends, while circumferential periodicity is preserved. The final system of nonhomogeneous differential equations is solved numerically using the discrete orthogonalization method. The proposed approach provides accurate results for structures operating under complex loading conditions and can be effectively applied to improve their reliability and safety.

Low-symmetry crystals have emerged as a platform for exploring unique light-matter interactions in the form of hyperbolic shear polaritons. These excitations exhibit unique properties such as frequency-dispersive optical axes and asymmetric light propagation and energy dissipation. However, only non-vdW materials have been demonstrated to support hyperbolic shear polaritons, limiting their exotic properties and potential applications. Here, we introduce shear phenomena in low symmetry crystals by demonstrating elliptical and canalized shear phonon polaritons in gypsum, an exfoliable monoclinic sulphate mineral. Our results unveil a topological transition from hyperbolic shear to elliptical shear polaritons, passing through a canalization regime with strong field confinement. We observe a notable slowdown of group velocity, reaching values as low as 0.0005 c . These findings expand the application scope of low-symmetry crystals with the benefits that an exfoliable material provides, such as stronger field confinement, tunability, and versatility for its incorporation in complex photonic devices.

Periodic plasmonic arrays, making possible excitations of surface lattice resonances (SLRs) or quasi-resonant features, are of great importance for biosensing and other applications. Fabrication of such arrays over a large area is typically very costly and time-consuming when performed using conventional electron beam lithography and other methods, which reduce application prospects. Here, we propose a technique of double femtosecond pulse (∼170 fs) laser-assisted structuring of thin (∼32 nm) Au films deposited on a glass substrate and report a single-step fabrication of homogeneous and highly ordered Au-based laser-induced periodic surface structures (LIPSS) over a large area. Our experimental results unveil the key importance of the interpulse delay as the determining factor rendering possible the homogeneity of laser-induced structures and confirm that highly ordered, functional LIPSS occurs solely upon double pulse irradiation under a specific interpulse delay range. A theoretical investigation complements experimental results, providing significant insights into the structure formation mechanism. Ellipsometric measurements show that such LIPSS structures can exhibit highly valuable plasmonic features in light reflection. In particular, we observed ultranarrow resonances associated with diffraction-coupled SLRs, which are of paramount importance for biosensing and other applications. The presented data suggest that femtosecond double pulse structuring of thin metal films can serve as a valuable and low-cost tool for large-scale fabrication of highly ordered functional elements and structures.

2D assemblies of resonant dielectric particles constitute promising materials for the next generation of photonic devices, thanks to their low optical losses and intense electromagnetic response. However, bottom‐up synthesis methods present many difficulties when targeting metasurface applications, particularly due to the high degree of positional disorder and the size dispersion of the resonant particles. This work presents the fabrication of core–shell silicon@silica particles with multipolar resonances in the visible and near‐infrared. These resonant particles are then assembled at an air–water interface into a semi‐ordered array with islands of crystallinity. The assembly is deposited on quartz and the optical properties are characterized with ellipsometry and optical microscopy. The effective medium of this material appears to display a magnetic resonance with a high‐quality factor at ≈945 nm, as demonstrated by a Lorentzian resonance in the permeability. Thus, this is the first bottom‐up synthesis of silicon particle assemblies known to generate optical magnetism, giving promise for the scalable production of high‐performance metasurfaces, in spite of the imperfections associated with bottom‐up fabrication.

Hydrogen bonding plays a crucial role in biology and technology, yet it remains poorly understood and quantified despite its fundamental importance. Traditional models, which describe hydrogen bonds as electrostatic interactions between electropositive hydrogen and electronegative acceptors, fail to quantitatively capture bond strength, directionality, or cooperativity, and cannot predict the properties of complex hydrogen-bonded materials. Here, we introduce a concept of hydrogen bonds as elastic dipoles in an electric field, which captures a wide range of hydrogen bonding phenomena in various water systems. Using gypsum, a hydrogen bond heterostructure with two-dimensional structural crystalline water, we calibrate the hydrogen bond strength through an externally applied electric field. We show that our approach quantifies the strength of hydrogen bonds directly from spectroscopic measurements and reproduces a wide range of key properties of confined water reported in the literature. Using only the stretching vibration frequency of confined water, we can predict hydrogen bond strength, local electric field, O-H bond length, and dipole moment. Our work also introduces hydrogen bond heterostructures – a class of electrically and chemically tunable materials that offer stronger, more directional bonding compared to van der Waals heterostructures, with potential applications in areas such as catalysis, separation, and energy storage.

Due to large anisotropy and tunable exciton transitions observed in visible light, transition metal dichalcogenides could become platform materials for on-chip next-generation photonics and nano-optics. For this to happen, one needs to be able to nanostructure transition metal dichalcogenides without losing their optical properties. However, both our understanding of the physics of such nanostructures and their technology are still at infancy and, therefore, experimental works on optics of transition metal dichalcogenides nanostructures are urgently required. Here, we study optical characteristics of bilayer MoS₂ nanoribbons by measuring reflection and photoluminescence of nanostructured bilayer MoS₂ flakes near exciton transitions. We show that there exist optically inactive “exciton-free” regions near the edges of nanoribbons with sizes of around 10 nm. We demonstrate that the “exciton-free” regions can be controlled by external electrical gating. These results are important for nanostructured optoelectronic devices made of MoS₂ and other transition metal dichalcogenides.

We study systems that approach a state possessing discrete symmetry due to different degenerate realizations for the system. For concreteness, we consider fractionally filled systems where degeneracy comes from the presence of identical sub-lattices. We show that such systems possess a new type of quasiparticles with fractional charges, which we refer to as fractyons. We discuss static and dynamic properties of these quasiparticles.