The constant progress in novel nanomaterials synthesis has contributed to the rapid development of nonenzymatic glucose sensors. For working electrodes preparation, drop casting proved to be the most convenient and thus most widely applied method. However, appropriate interpretation of obtained electrochemical signal requires in-depth knowledge of limitations related to this technique. In this study, we prepared solutions based on commonly reported polymers for nanostructures immobilization and investigated their influence on copper sulfides distribution on the electrode. Characterization of suspensions properties and behavior of particles during droplet drying revealed that nonionic polyvinylpyrrolidone (PVP) was favorable for electrodes modification with copper sulfides in comparison with Nafion and chitosan. It ensured homogeneity of the suspension as well as the uniform coverage of the electrode surface with particles, what resulted in increased active surface area and, therefore, higher signal from glucose addition. On the other hand, when cationic chitosan was used as a binder, suspensions were agglomerated and, within dry deposits, a coffee-ring effect was observed. Appropriate adjustment of material and polymer interactions led to enhanced electrode electrochemical performance.

The diversity of materials proposed for non-enzymatic glucose detection and the lack of standardized protocols for assessing sensor performance have caused considerable confusion in the field. Therefore, methods for pre-evaluation of working electrodes, which will enable their conscious design, are currently intensively sought. Our approach involved comprehensive morphologic and structural characterization of copper sulfides as well as drop-casted suspensions based on three different polymers—cationic chitosan, anionic Nafion, and nonionic polyvinylpyrrolidone (PVP). For this purpose, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy were applied. Subsequently, comparative studies of electrochemical properties of bare glassy carbon electrode (GCE), polymer- and copper sulfides/polymer-modified GCEs were performed using electrochemical impedance spectroscopy (EIS) and voltammetry. The results from EIS provided an explanation for the enhanced analytical performance of Cu-PVP/GCE over chitosan- and Nafion-based electrodes. Moreover, it was found that the pH of the electrolyte significantly affects the electrocatalytic behavior of copper sulfides, indicating the importance of OH_ads in the detection mechanism. Additionally, diffusion was denoted as a limiting step in the irreversible electrooxidation process that occurs in the proposed system.

The multi-component approach to materials design is gaining increasing popularity in energy-conversion-oriented applications. This study describes a 5-component multimetallic chalcogenide compound with a pentlandite structure that recently became increasingly interesting in terms of electrocatalytic water splitting. The solubility limit of Se in the trimetallic Co₃Fe₃Ni₃S₈ system was determined along with the potential effect of this additive on the material's intrinsic properties. This was followed by an unprecedented approach, an attempt to fabricate solid electrodes using the inductive hot-pressing method. The effects of the consolidation conditions on the morphology and final properties of the material are discussed in detail. Tailoring both the chemical composition and processing conditions (initial grain size, sintering temperature) can lead to the optimization of highly efficient electrocatalysts for water splitting. The best electrodes were characterized at elevated current densities of 120 mA cm⁻², showing low overpotentials (240 mV versus RHE) but with rather low electrochemical active surface area and moderately optimal reaction kinetics. It was therefore shown that using multi-component compositions resulted in good intrinsic properties of the materials toward hydrogen production, together with high density and vacancy concentrations provided by the sintering process, thus producing an efficient electrocatalyst using a simple, scalable method without any additional processing.

Flower-like copper sulfides nanostructures were synthesized via the solvothermal route. The structural, optical and electrochemical properties of the synthesized materials were characterized by means of X-ray diffraction (XRD), scanning electron microscopy, ultraviolet–visible spectrometry and Fourier transform infrared spectroscopy (FTIR). Thermal behavior of the obtained flower-like materials was analyzed by TG, XRD and FTIR in situ measurements, over the temperature range of 25–800 °C. It was found that both shape and phase composition remain stable until the temperature reaches 200 °C. Phase transformation mechanism was discussed. During annealing, mixture of CuS and Cu_1.8S is converted to copper sulfide hydroxides (200–500 °C) and further to CuO (700 °C and higher). Nevertheless, hierarchically porous structure is stable only to 200 °C. Applying higher temperatures affects the solubility of the material and inflicts structural damage, resulting in the formation of dense oval particles with size of 20 to 200 nm.

The impact of the reaction environment on the formation of the polycrystalline layer and its biomedical (antimicrobial) applications were analyzed in detail. Copper oxide layers were synthesized using an electrodeposition technique, with varying additives influencing the morphology, thickness, and chemical composition. Scanning electron microscopy (SEM) images confirmed the successful formation of polyhedral structures. Unmodified samples (CuL) crystallized as a mixture of copper oxide (I) and (II), with a thickness of approximately 1.74 μm. The inclusion of the nonconductive polymer polyvinylpyrrolidone (PVP) during synthesis led to a regular and compact CuO-rich structure (CuL-PVP). Conversely, adding glucose resulted in forming a Cu₂O-rich nanostructured layer (CuL-D(+)G). Both additives significantly reduced the sample thickness to 617 nm for CuL-PVP and 560 nm for CuL-D(+)G. The effectiveness of the synthesized copper oxide layers was demonstrated in their ability to significantly reduce the T4 phage titer by approximately 2.5-3 log. Notably, CuL-PVP and CuL-D(+)G showed a more substantial reduction in the MS2 phage titer, achieving about a 5-log decrease. In terms of antibacterial activity, CuL and CuL-PVP exhibited moderate efficacy against Escherichia coli, whereas CuL-D(+)G reduced the E. coli titer to undetectable levels. All samples induced similar reductions in Staphylococcus aureus titer. The study revealed differential susceptibilities, with Gram-negative bacteria being more vulnerable to CuL-D(+)G due to its unique composition and morphology. The antimicrobial properties were attributed to the redox cycling of Cu ions, which generate ROS, and the mechanical damage caused by nanostructured surfaces. A crucial finding was the impact of surface composition rather than surface morphology on antimicrobial efficacy. Samples with a dominant Cu₂O composition exhibited potent antibacterial and antiviral properties, whereas CuO-rich materials showed predominantly enhanced antiviral activity. This research highlights the significance of phase composition in determining the antimicrobial properties of copper oxide layers synthesized through electrodeposition.