Alina Gorbunova

Plasmonic microchannels are patterned by laser-induced in situ Au NPs reduction on MOF-functionalized PET for reducing fabrication steps and costs towards plasmon-active microfluidic chips design.

Plasmon-assisted catalysis offers an attractive route for solar-to-chemical energy conversion, yet its practical integration into scalable flow systems remains limited by complex fabrication steps and poor nanoparticle stability. Here, we report a one-step laser-assisted method for simultaneously forming gold nanoparticles (Au NPs) and patterning microchannels on metal-organic framework (MOF)-functionalized polyethylene terephthalate (PET) substrates derived from waste plastic. Using a 405 nm laser, the in-situ reduction of HAuCl₄ within a UiO-66 matrix deposited on PET enables homogeneous Au NPs formation (≈5.4 nm) and precise microchannel definition without the need for additional reagents or post-processing. The resulting PET@Au composites exhibit strong plasmon resonance at 550 nm and catalytic activity for the degradation of methylene blue under visible light, confirming their functional performance. This approach combines plasmonic functionality, low-cost materials, and sustainable processing into a scalable platform for the development of integrated microfluidic and photocatalytic devices.

The progress in plasmonic chemistry requires research on energy transfer, mechanisms, and materials discovery. In this pursuit, there are >3000 papers applying the azo coupling of 4-nitrothiophenol (PNTP) as a model reaction. Here, we challenge the status of this reaction as a model due to experimental evidence of thiol desorption during plasmon excitation using laser irradiation monitored by X-ray photoelectron spectroscopy (XPS) as an analytic technique. The azo coupling was performed on commonly used Au nanoparticles (NPs) coated with PNTP and confirmed by Raman spectroscopy and XPS. Changes in the N 1s and S 2p spectral regions indicated the cleavage of the Au–S bond, accompanied by thiol oxidation. Based on XPS data, we hypothesized a chemical pathway and a kinetic model that surpasses previously used simple models in complexity, making it challenging to draw reliable conclusions. The dissociation of the Au–S bond is triggered by plasmonic heating, supported by experimentally and theoretically determined local temperatures exceeding the thiol desorption temperature. The azo coupling reaction does not fit within the requirements of the model one, which should be simple and proceed with structurally evidenced products. As one of the alternative reactions, we suggest alkoxyamine homolysis tracked by electron paramagnetic resonance spectroscopy because of known products and the simple kinetic model. Applications of suitable model reactions accelerate discoveries in plasmon catalysis.

Graphene oxide (GO) possesses specific properties that are revolutionizing materials science, with applications extending from flexible electronics to advanced nanotechnology. A key method for harnessing GO’s potential is its laser-induced reduction, yet the exact mechanisms — photothermal versus photochemical effects — remain unclear. Herein, we discover the dominant role of photochemical reactions in the laser reduction of GO under visible light, challenging the prevailing assumption that photothermal effects are dominant. Employing a combination of Raman thermometry, X-ray photoelectron and photoluminescence spectroscopies, and electrical atomic force microscopy, we quantify the temperature and map the reduction process across micro and nano scales. Our findings demonstrate that the photochemical cleavage of oxygen-containing groups below a reduction threshold temperature is a decisive factor in GO reduction, leading to distinct characteristics that cannot be replicated by heating alone. This work clarifies the fundamental mechanisms of GO transformation under visible laser irradiation, highlighting the dominant role of photochemical processes. Distinguishing these subtleties enables the development of laser-reduced GO platforms for graphene-based applications compatible with industrial scales. We illustrate this potential by encoding information on GO surfaces as optical storage, allowing us to write binary sequences in long-term memory encoding invisible even through an optical microscope.

This work uses the direct current magnetron sputtering (DCMS) of equi-atomic (AlTiZrHfTa) and Si targets in dynamic sweep mode to deposit nano-layered (AlTiZrHfTa)N_x/SiN_x refractory high-entropy coatings (RHECs). Transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) are used to investigate the effect of Si addition on the oxidation behavior of the nano-layered coatings. The Si-free nitride coating exhibits FCC structure and columnar morphology, while the Si-doped nitride coatings present a FCC (AlTiZrHfTa)N/amorphous-SiN_x nano-layered architecture. The hardness decreases from 24.3 ± 1.0 GPa to 17.5 ± 1.0 GPa because of the nano-layered architecture, whilst Young’s modulus reduces from 188.0 ± 1.0 GPa to roughly 162.4 ± 1.0 GPa. By increasing the thickness of the SiN_x nano-layer, k_p values decrease significantly from 3.36 × 10⁻⁸ g² cm⁻⁴ h⁻¹ to 6.06 × 10⁻⁹ g² cm⁻⁴ h⁻¹. The activation energy increases from 90.8 kJ·mol⁻¹ for (AlTiZrHfTa)N_x nitride coating to 126.52 kJ·mol⁻¹ for the (AlTiZrHfTa)N_x/SiN_x nano-layered coating. The formation of a FCC (AlTiZrHfTa)-N_x/a-SiN_x nano-layered architecture results in the improvement of the resistance to oxidation at high temperature.

In this study, we propose an approach to the synthesis of new biodegradable polymer materials based on renewable raw feedstock (betulin) and derivatives of hydroxycarboxylic acids using a catalyst/catalytic system (γ-Al₂O₃, γ-Al₂O₃/TBHP) that is safe for health and the environment. The resulting polymers are linear thermoplastic polymers that undergo collapse upon melting in the presence of atmospheric oxygen. Moreover, these polymers demonstrate non-toxicity towards a range of Gram-positive and Gram-negative bacteria. The polycondensation of betulin with butyl lactate is particularly noteworthy.

The growing accumulation of waste polyethylene terephthalate (PET) presents a significant environmental challenge requiring the development of sustainable recycling methods. In this study, we propose a novel approach for upcycling PET waste into bend resistive sensors through laser-assisted carbonization of surface-grown Ni-BDC (BDC = 1,4-benzenedicarboxylate). The fabrication process involves the solvothermal formation of a homogeneous Ni-BDC layer, followed by treatment with a 405 nm laser system to create a graphene-like layer with enhanced conductivity (sheet resistance 6.2 ± 3.4 Ω per square). The developed sensor demonstrates remarkable robustness, a linear response in a wide bending angle range (6 to 44º), as well as excellent mechanical stability and stiffness. This contribution paves the way for the development of cost-effective and eco-friendly devices based on low-cost polymer waste as a resource for applications in the Internet of Things.

This article reviews recent fabrication methods for surface‐enhanced Raman spectroscopy (SERS) substrates with a focus on advanced nanoarchitecture based on noble metals with special nanospaces (round tips, gaps, and porous spaces), nanolayered 2D materials, including hybridization with metallic nanostructures (NSs), and the contemporary repertoire of nanoarchitecturing with organic molecules. The use of SERS for multidisciplinary applications has been extensively investigated because the considerably enhanced signal intensity enables the detection of a very small number of molecules with molecular fingerprints. Nanoarchitecture strategies for the design of new NSs play a vital role in developing SERS substrates. In this review, recent achievements with respect to the special morphology of metallic NSs are discussed, and future directions are outlined for the development of available NSs with reproducible preparation and well‐controlled nanoarchitecture. Nanolayered 2D materials are proposed for SERS applications as an alternative to the noble metals. The modern solutions to existing limitations for their applications are described together with the state‐of‐the‐art in bio/environmental SERS sensing using 2D materials‐based composites. To complement the existing toolbox of plasmonic inorganic NSs, hybridization with organic molecules is proposed to improve the stability of NSs and selectivity of SERS sensing by hybridizing with small or large organic molecules.

Herein, it has been shown that betulin can be transformed into its biologically active oxo-derivatives (betulone, betulinic and betulonic aldehydes) by liquid-phase oxidation over supported silver catalysts under mild conditions. In order to identify the main factors determining the catalytic behavior of nanosilver catalysts in betulin oxidation, silver was deposited on various alumina supports (γ-alumina and boehmite) using deposition–precipitation with NaOH and incipient wetness impregnation methods, followed by treatment in H₂ or O₂. Silver catalysts and the corresponding supports were characterized by X-ray diffraction, nitrogen physisorption, inductively coupled plasma optical emission spectroscopy, photoelectron spectroscopy and transmission electron microscopy. It was found that the support nature, preparation and treatment methods predetermine not only the average Ag nanoparticles size and their distribution, but also the selectivity of betulin oxidation, and thereby, the catalytic behavior of Ag catalysts. In fact, the support nature had the most considerable effect. Betulin conversion, depending on the support, increased in the following order: Ag/boehmite < Ag/boehmite (calcined) < Ag/γ-alumina. However, in the same order, the share of side reactions catalyzed by strong Lewis acid centers of the support also increased. Poisoning of the latter by NaOH during catalysts preparation can reduce side reactions. Additionally, it was revealed that the betulin oxidation catalyzed by nanosilver catalysts is a structure-sensitive reaction.