Information on vitamin C—ascorbic acid (AA)—content is important as it facilitates the provision of dietary advice and strategies for the prevention and treatment of conditions associated with AA deficiency or excess. The methods of determining AA content include chromatographic techniques, spectrophotometry, and electrochemical methods of analysis. In the present work, an electrochemical enzyme-free ascorbic acid sensor for a neutral medium has been developed. The sensor is based on zinc oxide nanowire (ZnO NW) arrays synthesized via low-temperature chemical deposition (Chemical Bath Deposition) on the surface of an ITO substrate. The sensitivity of the electrochemical enzyme-free sensor was found to be dependent on the process treatments. The AA sensitivity values measured in a neutral PBS electrolyte were found to be 73, 44, and 92 µA mM⁻¹ cm⁻² for the ZnO NW-based sensors of the pristine, air-annealed (AT), and air-annealed followed by hydrogen plasma treatment (AT+PT), respectively. The simple H-plasma treatment of ZnO nanowire arrays synthesized via low-temperature chemical deposition has been shown to be an effective process step to produce an enzyme-free sensor for biological molecules in a neutral electrolyte for applications in health care and biomedical safety.

In this work, the synthesis of nickel particles encapsulated in a few-layer graphene shell was carried out using the method of electric arc discharge in the liquid phase, in various media: deionized water, alcohol, and toluene. Nickel and graphite were used as electrodes. The study was carried out to analyze how various liquids, acting as a cooling medium and a source of carbon, affect the formation of a protective shell around metal particles. Raman studies, analysis of X-ray diffraction data, and scanning electron microscopy confirmed the formation of spherical encapsulated nickel particles in all types of liquid media. It was found out that the use of toluene as a cooling medium increased the number of particles with a graphite shell and allowed obtaining micro- and nanoparticles covered with monolayer graphene. The absence of oxygen in the composition of toluene, in contrast with alcohol and especially water, prevents the oxidation of nickel particles during the synthesis. This fact, along with the initial basic hexagonal carbon structure of toluene, makes it a good medium for the formation of metal particles covered with a protecting graphite shell as a result of arc discharge in the liquid phase.

In recent years, interest in the liquid-phase exfoliation (LPE) of layered crystals has been growing due to the efficiency and scalability of the method, as well as the wide range of practical applications of the obtained dispersions based on two-dimensional flakes. In this paper, we present a comparative study of as-grown and liquid-phase exfoliated GaSe_1−xS_x flakes. Bulk GaSe_1−xS_x crystals with x ~ 0, 0.25, 0.5, 0.75, 1 were synthesized by melting stoichiometric amounts of gallium, selenium, and sulfur particles in evacuated ampoules. X-ray diffraction analysis showed that the crystal structure does not change considerably after LPE, while the analysis of the Raman spectra revealed that, after liquid-phase processing in IPA, an additional peak associated with amorphous selenium is observed in selenium-rich GaSeS compounds. Nevertheless, the direct and indirect transition energies determined from the Kubelka-Munk function for LPE crystals correlate with the band gap of the as-grown bulk GaSeS crystals. This finding is also confirmed by comparison with the data on the positions of the photoluminescence peak.

In the work, porous silicon with observed photoluminescence was made from a p-type silicon substrate doped with boron and crystallographic orientation (100) using the method of electrochemical etching in a solution containing H₂(SiF₆) (silicon hydrofluoric acid) and ethyl alcohol. Thin carbon films were sprayed by high-frequency magnetron sputtering at room temperature onto the surface of porous silicon. The resulting carbon-doped thin films of porous silicon were irradiated on a pulsed electron booster and comparisons were made with nonirradiated films of porous silicon. To understand the effect of carbon on the properties of porous silicon films samples were analyzed by Raman spectroscopy, spectrophotometry, and scanning probe microscopy (SPM). The results of the SPM showed that the roughness of the samples increases after carbon doping on the surface of porous silicon. Thus, for the first time, experimental results were obtained on the effect of irradiation on carbon-doped porous silicon obtained in a solution containing hydrogen hexafluorosilicate H₂(SiF₆) and a significant change in its optical properties was shown. The results of the study showed that irradiated samples of carbon-doped porous silicon have better photoluminescence compared to nonirradiated samples.

Nanostructured semiconductor ZnO and ZnO-GO samples were synthesized at room temperature by chemical bath deposition technique. In this work, the electrochemical non-enzymatic determination of ascorbic acid was studied using the grown nanostructures deposited on a glassy carbon electrode. The morphology and structural properties of the synthesized nanostructured materials were analyzed using a scanning electron microscope and an X-ray diffractometer. The electrochemical properties were studied by the methods of cyclic voltammetry using a single-channel potentiostat-galvanostat. The sensitivity of the obtained electrodes was calculated based on concentrations of ascorbic acid in phosphate buffer solution from 0.3 mM to 3 mM at various scanning speeds. Thus, it was found that the sensitivity of the ZnO-GO sample is lower than that of the ZnO sample, which may be due to the dielectric properties of graphene oxide. However, after annealing in the atmosphere, the sensitivity of the ZnO-GO sample increased, which is associated with a decrease in defects in the sample and an increase in the specific surface area of the samples. As a result of the research, a modified ZnO-GO/GCE electrode with a high sensitivity of 386 μAM-1cm-2 was created, which is promising for use as the basis of a biosensor for determining the level of vitamin C in blood, food, and drugs. Полупроводниковые наноструктурированные образцы ZnO и ZnO-GO были получены при комнатной температуре методом химического осаждения из раствора. В работе исследовано электрохимическое неферментативное определение аскорбиновой кислоты с помощью полученных наноструктур, нанесённых на стеклоуглеродный электрод. Морфология и структурные свойства изготовленных наноструктурированных материалов были проанализированы с помощью электронного растрового микроскопа и рентгеновского дифрактометра. Электрохимические свойства были исследованы методами циклической вольтамперометрии на одноканальном потенциостате-гальваностате. Чувствительность полученных электродов была рассчитана для концентраций аскорбиновой кислоты в фосфатно-буферном растворе от 0,3мМ до 3 мМ при различных скоростях сканирования. Таким образом, было выявлено, что чувствительность образца ZnO-GO ниже, чем у образца ZnO, что может быть связано с диэлектрическими свойствами оксида графена. Однако после отжига в атмосфере чувствительность образца ZnO-GO повысилась, что связано с уменьшением дефектов в образце и увеличением удельной поверхности образцов. В результате исследований был получен модифицированный ZnO-GO/GCE электрод с высокой чувствительностью 386 мкАМ-1см-2, перспективный для использования в качестве основы биосенсора для определения уровня витамина C в крови, пищевых продуктах и лекарствах. ZnO және ZnO - GO наноқұрылымды жартылай өткізгіш үлгілері ерітіндіден химиялық тұндыру әдісімен бөлме температурасында алынды. Жұмыста шыны көміртекті электродқа қолданылатын алынған наноқұрылымдардың көмегімен аскорбин қышқылының электрохимиялық ферментативті емес анықтамасы зерттелді. Өндірілген наноқұрылымды материалдардың морфологиясы мен құрылымдық қасиеттері электронды растрлық микроскоп пен рентгендік дифрактометрдің көмегімен талданды. Электрохимиялық қасиеттері бір арналы потенциостат-гальваностаттағы циклдік вольтамметрия және амперометрия әдістерімен зерттелді. Алынған электродтардың сезімталдығы әртүрлі сканерлеу жылдамдықтарында 0,3 мМ-ден 3 мМ-ге дейінгі фосфат-буферлік ерітіндідегі аскорбин қышқылының концентрациясы үшін есептелген. Осылайша, ZnO - GO үлгісінің сезімталдығы ZnO үлгісіне қарағанда төмен екендігі анықталды, бұл графен оксидінің диэлектрлік қасиеттеріне байланысты болуы мүмкін. Алайда, атмосферада күйдірілгеннен кейін ZnO-go үлгісінің сезімталдығы жоғарылады, бұл үлгідегі ақаулардың азаюына және үлгілердің меншікті бетінің ұлғаюына байланысты. Зерттеулер 386 мкАМ-1 см-2 жоғары...

ZnS is one of the most promising wide-bandgap semiconductors for optoelectronic and sensing applications owing to its efficient ultraviolet–blue emission, high exciton binding energy, and chemical stability. However, the synthesis of ZnS nanocrystals in silicon-compatible porous matrices remains largely unexplored. In this work, ordered arrays of ZnS nanocrystals were synthesized for the first time in SiO₂/Si track templates fabricated by swift heavy ion irradiation followed by selective chemical etching. ZnS nanocrystals were deposited by electrochemical deposition from aqueous solutions containing ZnCl₂ and thiourea precursors. The structural, optical, and electrical properties of the resulting ZnS/SiO₂/Si nanocomposites were investigated using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, photoluminescence spectroscopy, and electrical measurements. The fabricated templates contained vertically aligned pores with a density of approximately 10⁸ cm⁻² and an average diameter of about 500 nm. Electrochemical deposition resulted in a pore filling efficiency of approximately 88%. X-ray diffraction analysis confirmed the formation of crystalline ZnS with a cubic zinc blende structure. The nanocomposites exhibit intense ultraviolet–blue photoluminescence in the 335–477 nm range, with pronounced emission peaks at 372 and 400 nm characteristic of ZnS nanocrystals. Current–voltage measurements indicate predominantly electronic conductivity, with a conductivity of 1.54 × 10⁻⁶ Ohm⁻¹·cm⁻¹, comparable to values reported for polycrystalline ZnS films. To support the experimental observations, the electronic structure of ZnS was analyzed using density functional theory within the LCAO framework. The calculated bandgap of 3.4 eV is consistent with previously reported theoretical and experimental data. The obtained results demonstrate that SiO₂/Si track templates provide a promising platform for the fabrication of ordered ZnS nanoarrays with potential applications in silicon-compatible optoelectronic and sensing devices.