To evaluate the potential role of in situ formed Sr-Ti-O species as a ferroelectric component able to enhance the photocatalytic properties of an adjacent TiO2 semiconductor, Cu-doped/graphene oxide (GO)/TiO2 nanotubes (TiNTs) composites (with 0.5 wt % Cu and 1.0 wt % GO) have been synthesized while progressive amounts of strontium (up to 1.0 wt %) were incorporated at the surface of the composite through incipient wetness impregnation followed by post-thermal treatment at 400 degrees C. The different resulting photocatalytic systems were then first deeply characterized by means of N2 adsorption-desorption measurements, X-ray diffraction (XRD), UV-vis diffuse reflectance (UV-vis DR), Raman and photoluminescence (PL) spectroscopies, and scanning electron microscopy (SEM) (with energy-dispersive X-ray (EDX) spectroscopy and Z-mapping). In a second step, optimization of the kinetic response of the Sr-containing composites was performed for the formic acid photodegradation under UV irradiation. The Sr-containing Cu/GO/TiNT composites were then fully characterized by electrochemical impedance spectroscopy (EIS) for their dielectric properties showing clearly the implication of polarization induced by the Sr addition onto the stabilization of photogenerated charges. Finally, a perfect correlation between the photocatalytic kinetic evaluation and dielectric properties undoubtedly emphasizes the role of ferroelectric polarization as a very valuable approach to enhance the photocatalytic properties in an adjacent semiconductor.

In this work, vanadium pentoxide nanoparticles (V₂O₅) derived by the chemical coprecipitation route were used to synthesize various vanadium-doped ZnO nanocomposite samples via the standard solid-state reaction process. The effect of V₂O₅ nanoparticles on the physicochemical properties of ZnO was discussed. The prepared samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy combined with energy-dispersive spectroscopy, and UV-visible spectroscopy. A diffuse reflectance spectroscopic approach is described to determine the bandgap energy (Eg) of the samples. The dielectric and photocatalytic characteristics are also examined. The photocatalytic performance of the prepared materials was tested under visible light using methylene blue (MB) as a pollutant dye model. As a result, it is found that the addition of V₂O₅ enhances the photodegradation of MB. The kinetics of the photodegradation reaction was found to follow a pseudo-first-order model.

This work examines the antibacterial and anticandidal activities of zinc oxide nanoparticles (ZNPs) synthesized by high-speed ball milling (HSBM), for short milling times: 0.5, 1, 1.5, and 2h. First, ZNPs have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and the Zetasizer analyzer. The HSBM results in semispherical ZNPs with some local agglomeration. We found that nanoparticles decrease in size continuously with milling time until they reach about 84 of their original size after only two hours; at 1000rpm, HSBM reduces ZNPs average size by 6nm/min. As particle size decreases, the X-ray diffracted patterns become broader and less intense while confirming that no phase transformation has occurred, proving HSBMs effectiveness in synthesizing nanoparticles on a large scale within a short period of time. According to FT-IR analysis, as material sizes change, the polarization charge of the ZNP surface changes as well, creating discrepancies in vibrational frequency, as demonstrated by the shifting of the IR spectra in the 300600cm⁻¹ frequency band. Raman responses have also been proven to depend on the particle size. Using the Agar well diffusion method, eleven microorganisms have been tested for the antimicrobial activity of ZNPs. Among the six Gram-negative tested bacteria, S. sonnei showed the largest inhibition zone of about 11.3±0.6mm with ZNPs measuring 148nm in size (milled for 2h), followed by E. coli ATCC 25922. Accordingly, S. aureus was the most susceptible Gram-positive bacteria, with inhibition zone size gradually increasing from 11.8±0.3mm to 13.5±0.5mm with decreasing nanoparticle size from 767 to 148nm, while S. aureus ATCC 25923 was resistant to both milled and unmilled samples. Similar results were seen with candida, all milled ZNPs inhibited C. albicans, followed by C. tropicalis, whereas C. knisei was resistant to all ZNP sizes. In light of microorganism-ZNP interaction mechanisms, the obtained results have been discussed in depth.