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Herein, we investigated CeVO4 nanostructures synthesized using a microwave-assisted hydrothermal method, focusing on their structural and electrochemical properties for potential supercapacitor applications. Notably, the selected synthesis method yielded a material that displays lattice spacing consistent with the (200) plane of the tetragonal CeVO4 structure, as confirmed by high-resolution transmission electron microscopy and corroborated by X-ray diffraction analysis. In addition, EDX spectroscopy demonstrated the high purity of the sample, with only Ce, V, and O elements presented, and XPS analysis revealed the chemical composition of the elements and oxidation states on the surface, with Ce3+, Ce4+, and V5+ identified. Following, cyclic voltammetry tests indicated pseudocapacitive behavior with well-defined redox peaks and good capacitive behavior and stability; then, galvanostatic charge–discharge profiles exhibited high specific capacitances at various current densities. After such analyses, an asymmetric supercapacitor was assembled using activated carbon as a cathode, and it demonstrated an excellent energy density value of 424.43 Wh kg−1 at a power density of 2783.11 W kg−1 (1 A g−1 in 2.0 M KOH). Thus, the comprehensive structural and electrochemical characterizations provided valuable insights into the material's potential for energy storage systems. [ABSTRACT FROM AUTHOR]

In the face of current energy and environmental challenges, electrochemical storage devices emerge as a promising alternative. Specifically, supercapacitors are highly valued for their exceptional ability to deliver rapid responses and exhibit high-power capabilities. Although rare-earth compounds have received less attention in the electrochemical storage field, the utilization of nanotechnology tools allows for precise manipulation of their shape and size, which opens new possibilities for developing novel configurations with improved properties, presenting previously unexplored applications. Herein, we set a new electrode material consisting of nanospheres of gadolinium vanadate (GdVO4) synthesized by microwave-assisted hydrothermal method, which was a crucial component in preparing nickel foam-based electrodes. The material was thoroughly characterized, revealing interesting properties for energy storage applications. The electrode delivered a high specific capacitance of 1203.75 F g−1 at 1 A g−1 and good cycling stability after 500 cycles. Then, an asymmetric supercapacitor was performed, reaching 80.63 F g−1 at 1 A g−1 and 130.2 Wh kg−1 of energy density when the power density was 2880.18 W kg−1. Thus, this study highlights the potential of GdVO4 as an electrode material in electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]

In this work, α-Ag2−2xCuxWO4 (0 ≤ x ≤ 0.16) solid solutions with enhanced antibacterial (against methicillin-resistant Staphylococcus aureus) and antifungal (against Candida albicans) activities are reported. A plethora of techniques (X-ray diffraction with Rietveld refinements, inductively coupled plasma atomic emission spectrometry, micro-Raman spectroscopy, attenuated total reflectance–Fourier transform infrared spectroscopy, field emission scanning electron microscopy, ultraviolet–visible spectroscopy, photoluminescence emissions, and X-ray photoelectron spectroscopy) were employed to characterize the as-synthetized samples and determine the local coordination geometry of Cu2+ cations at the orthorhombic lattice. To find a correlation between morphology and biocide activity, the experimental results were sustained by first-principles calculations at the density functional theory level to decipher the cluster coordinations and electronic properties of the exposed surfaces. Based on the analysis of the under-coordinated Ag and Cu clusters at the (010) and (101) exposed surfaces, we propose a mechanism to explain the biocide activity of these solid solutions. [ABSTRACT FROM AUTHOR]

In the current COVID-19 pandemic, the next generation of innovative materials with enhanced anti-SARS-CoV-2 activity is urgently needed to prevent the spread of this virus within the community. Herein, we report the synthesis of chitosan/α-Ag2WO4 composites synthetized by femtosecond laser irradiation. The antimicrobial activity against Escherichia coli, Methicilin-susceptible Staphylococcus aureus (MSSA), and Candida albicans was determined by estimating the minimum inhibitory concentration (MIC) and minimal bactericidal/fungicidal concentration (MBC/MFC). To assess the biocompatibility of chitosan/α-Ag2WO4 composites in a range involving MIC and MBC/MFC on keratinocytes cells (NOK-si), an alamarBlue™ assay and an MTT assay were carried out. The SARS-CoV-2 virucidal effects was analyzed in Vero E6 cells through viral titer quantified in cell culture supernatant by PFU/mL assay. Our results showed a very similar antimicrobial activity of chitosan/α-Ag2WO4 3.3 and 6.6, with the last one demonstrating a slightly better action against MSSA. The chitosan/α-Ag2WO4 9.9 showed a wide range of antimicrobial activity (0.49–31.25 µg/mL). The cytotoxicity outcomes by alamarBlue™ revealed that the concentrations of interest (MIC and MBC/MFC) were considered non-cytotoxic to all composites after 72 h of exposure. The Chitosan/α-Ag2WO4 (CS6.6/α-Ag2WO4) composite reduced the SARS-CoV-2 viral titer quantification up to 80% of the controls. Then, our results suggest that these composites are highly efficient materials to kill bacteria (Escherichia coli, Methicillin-susceptible Staphylococcus aureus, and the yeast strain Candida albicans), in addition to inactivating SARS-CoV-2 by contact, through ROS production. [ABSTRACT FROM AUTHOR]

In this work, we investigated the effects of chemical substitution on the structural, electronic, and optical properties of α-Ag2−2xNixWO4 (0 ≤x≤ 0.08) solid solutions prepared by a facile microwave-assisted hydrothermal method. The results showed that the increase of Ni concentration in α-Ag2WO4 microcrystals as a host matrix caused a morphological transformation and a shift of the electronic and optical properties. Based on first principles calculations and using Wulff's construction, particle shapes and their transformations in α-Ag2WO4 and α-Ag2−2xNixWO4 can be affected by controlling the ratios of surface energy values between the different facets. In addition, theoretical calculations revealed that Ni substitution in α-Ag2WO4 is more favorable in the Ag2 and Ag4 positions, in which the local coordination of Ag atoms corresponds to clusters with coordination numbers of seven and four, respectively. This behavior could be related to the degree of medium-range structural disorder in α-Ag2−2xNixWO4 crystals. The experimental results were correlated with theoretical simulations to achieve a deeper understanding of the relationship between morphology and properties. These results provide the basis for a rational design for the compositional modulation of structural and optical properties. [ABSTRACT FROM AUTHOR]