Activated carbons (ACs) have been the most widespread carbon materials used in supercapacitors (SCs) due to their easy processing methods, good electrical conductivity, and abundant porosity. For the manufacture of electrodes, the obtained activated carbon based on sawdust (karagash and pine) was mixed with conductive carbon and polyvinylidene fluoride as a binder, in ratios of 75% activated carbon, 10% conductive carbon black, and 15% polyvinylidene fluoride (PVDF) in an N-methyl pyrrolidinone solution, to form a slurry and applied to a titanium foil. The total mass of each electrode was limited to vary from 2.0 to 4.0 mg. After that, the electrodes fitted with the separator and electrolyte solution were symmetrically assembled into sandwich-type cell construction. The carbon’s electrochemical properties were evaluated using cyclic voltammetry (CV) and galvanostatic charge–discharge (CGD) studies in a two-electrode cell in 6M KOH. The CV and CGD measurements were realized at different scan rates (5–160 mV s⁻¹) and current densities (0.1–2.0 A g⁻¹) in the potential window of 1 V. ACs from KOH activation showed a high specific capacitance of 202 F g⁻¹ for karagash sawdust and 161 F g⁻¹ for pine sawdust at low mass loading of 1.15 mg cm⁻² and scan rate of 5 mV s⁻¹ in cyclic voltammetry test and 193 and 159 F g⁻¹ at a gravimetric current density of 0.1 A g⁻¹ in the galvanostatic charge–discharge test. The specific discharge capacitance is 177 and 131 F g⁻¹ at a current density of 2 A g⁻¹. Even at a relatively high scan rate of 160 mV s⁻¹, a decent specific capacitance of 147 F g⁻¹ and 114 F g⁻¹ was obtained, leading to high energy densities of 26.0 and 22.1 W h kg⁻¹ based on averaged electrode mass. Surface properties and the porous structure of the ACs were studied by scanning electron microscopy, energy-dispersive X-ray analysis, Raman spectroscopy, and the Brunauer–Emmett–Teller method.

Recently, heterostructured photocatalysts have gained significant attention in the field of photocatalysis due to their superior properties compared to single photocatalysts. One of the key advantages of heterostructured photocatalysts is their ability to enhance charge separation and broaden the absorption spectrum, thereby improving photocatalytic efficiency. Zinc oxide is a widely used n-type semiconductor with a proper photoelectrochemical activity. In this study, zinc oxide nanorod arrays were synthesized, and then the surfaces of ZnO nanorods were modified with the p-type semiconductor Co₃O₄ to create a p–n junction heterostructure. A significant increase in the photocurrent for the ZnO/Co₃O₄ composite, of 4.3 times, was found compared to pure ZnO. The dependence of the photocurrent on the morphology of the ZnO/Co₃O₄ composite allows for optimization of the morphology of the ZnO nanorod array to achieve improved photoelectrochemical performance. The results showed that the ZnO/Co₃O₄ heterostructure exhibited a photocurrent density of 3.46 mA/cm², while bare ZnO demonstrated a photocurrent density of 0.8 mA/cm² at 1.23 V. The results of this study provide a better understanding of the mechanism of charge separation and transfer in the heterostructural ZnO/Co₃O₄ photocatalytic system. Furthermore, the results will be useful for the design and optimization of photocatalytic systems for water splitting and other applications.

Silicon nanowires (SiNWs) prepared by metal-assisted chemical etching of crystalline silicon wafers followed by deposition of plasmonic gold (Au) nanoparticles (NPs) were explored as templates for surface-enhanced Raman scattering (SERS) from probe molecules of Methylene blue and Rhodamine B. The filling factor by pores (porosity) of SiNW arrays was found to control the SERS efficiency, and the maximal enhancement was observed for the samples with porosity of 55%, which corresponded to dense arrays of SiNWs. The obtained results are discussed in terms of the electromagnetic enhancement of SERS related to the localized surface plasmon resonances in Au-NPs on SiNW’s surfaces accompanied with light scattering in the SiNW arrays. The observed SERS effect combined with the high stability of Au-NPs, scalability, and relatively simple preparation method are promising for the application of SiNW:Au-NP hybrid nanostructures as templates in molecular sensorics.

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.