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Industrialisation has led to unprecedented levels of outdoor air pollution, posing a significant health risk to human beings. Consequently, there is an urgent need to replace fossil fuels with sustainable energy sources, thereby mitigating these risks and providing a safer outdoor and indoor environment. Titanium dioxide is a versatile transition metal oxide with applications ranging from energy conversion to environmental remediation. However, it faces limitations, particularly in its absorption spectrum and charge separation efficiency, and enhancing these properties remains a significant challenge. In this research work, we have decorated the surface of TiO2 hybridising it with noble‐metal and/or noble‐metal oxides (Ag and/or CuO) to improve the photocatalytic performances (monitoring the removal of nitrogen oxides and benzene, and hydrogen generation from water splitting) under simulated solar‐light irradiation. Our results showed that titania modified with an Ag : Cu molar ratio equal to 1 : 1, not only exhibited the most promising performance in terms of nitrogen oxides and benzene removal, it was the optimum amount for the light‐induced generation of hydrogen from water splitting. [ABSTRACT FROM AUTHOR]

Abstract: Anatase TiO2 has been prepared by mechanochemical synthesis using TiOSO4·xH2O and Na2CO3 as starting reactants. The reaction was performed in high-energy ball mill using steel and corundum jars, respectively. The final products were obtained by annealing the milled powder in the temperature range of 300–700°C and subsequently by washing out the water-soluble byproduct Na2SO4·xH2O. When steel jars were used, the annealing in the range of 300–600°C led to anatase. For products milled in corundum, the stability of anatase increased up to 700°C. Transition electron microscopy (TEM) showed that crystallites with a size in the range of 20–50nm with equiaxed morphology were obtained after milling in corundum and annealing at 600 and 700°C. The process of photoinduced reactive hydroxyl radical generation in aerated aqueous titania suspensions was studied by EPR spectroscopy using spin trapping technique. The presence of iron impurities in the samples milled in steel substantially decreases the radical formation. The rate of radical formation is substantially affected by particle size development of TiO2 nanopowders. The product milled in corundum and annealed at 700°C outperforms more than twice the photochemical activity of TiO2 Degussa P25 standard. [Copyright &y& Elsevier]

Abstract: Nanosized titania photocatalysts were prepared from a TiOSO4·2H2O–Na2CO3 mixture via high-energy milling for 5min, and subsequent annealing at a temperature range of 300–700°C/1h. Photoactivity of all samples monitored by electron paramagnetic resonance (EPR) spectroscopy was correlated with phase composition, crystallinity, crystal size and morphology of the annealed products. The anatase nanocrystals with an XRD average size of 24nm and well-faceted bipyramidal morphology exposed mainly by {101} type planes obtained on heating at 700°C, exhibited markedly higher photoactivity than the Aeroxide® P25 TiO2 standard and sample annealed at 600°C. The rapid increase in photoactivity was assigned to complete crystallization of the sample, optimal size, but mainly to the well-developed bipyramidal morphology of anatase nanocrystals and enlargement of the {101} type plane area due to final growth of bipyramids in the 〈001〉 direction. The weak beam dark field (WBDF) transmission electron microscopy (TEM) method was used to characterize morphology of the nanocrystals. Based on the thickness changes along the electron beam incidence inside the individual nanocrystals yielded by WBDF images, it was demonstrated that the mixture of polyhedral shaped anatase projections, such as square-like, hexagonal-like, rhomboid-like, rhombic-like, and rectangular-like prevailing in bright-field (BF) images, corresponds exclusively to tetragonal bipyramidal shape projected along different crystallographic directions. WBDF images of the most often occurring anatase nanocrystal projections are summarized and compared with both the schematic depictions of similarly oriented anatase bipyramids and that recorded in BF images. The difficulties of 3D morphology assessment from the projected nanocrystal shapes are highlighted. Attention is paid to the determination of facets limiting the nanocrystals, using the high resolution (HR)TEM method. [Copyright &y& Elsevier]

Acacetin (AC) is a natural polyphenol from the group of flavonoids. It is well established that the behavior of flavonoids depends on the presence of redox-active substances; therefore, we aim to investigate their biological activity following the interaction with Cu(II) ion. Our study demonstrates that AC can effectively bind Cu(II) ions, as confirmed by UV-Vis and EPR spectroscopy as well as DFT calculations. AC appears as a potent scavenger against the model ABTS radical cation by itself, but this ability is significantly limited upon Cu(II) coordination. The possible mild synergistic effect of AC in the presence of vitamin C and glutathione was also shown by the ABTS •+ test. In contrast, an inhibitory effect was observed in the presence of Cu(II) ions. The equimolar addition of AC to the model Fenton-like system containing Cu(II) did not have a noticeable effect on the concentration of hydroxyl radicals produced, but in its excess the formation of • OH decreased, as proved by EPR spin trapping. Absorption titrations and gel electrophoresis revealed effective binding to calf thymus (CT)-DNA with a stronger interaction for the Cu(II)-AC complex. The detailed mode of binding to biomolecules was described using molecular docking and molecular dynamics. Obtained results indicate that the double helix of DNA unwinds after interaction with the Cu(II)-AC complex. Fluorescence spectroscopy, employing human serum albumin (HSA), suggested a potential transport capacity for both AC and its Cu(II) complex., Competing Interests: Declaration of competing interest I, Miriama Malček Šimunková, hereby declare that I have no financial, personal, or other conflicts of interest that could have inappropriately influenced the content and conclusions of this work. This declaration is made in good faith and is true to the best of my knowledge., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Both nanometer-sized CuO and MgO particles exhibit bactericidal activities against Staphylococcus aureus and Escherichia coli , two bacteria causing healthcare-associated infections. The solid solution Cu 1- x Mg x O is potentially interesting for biomedical applications as one of the compositions could have a much higher bactericidal activity than the parent CuO and MgO oxides considered separately. But, to date, no Vegard's law proves the real existence of such a solid solution. This study was aimed at shedding light on the solubility of Mg 2+ ions in CuO nanoparticles and its impact on the free oxygen radicals they produce, the quantity of which determines their bactericidal performance. The solid solution Cu 1- x Mg x O does exist and particles were synthesized as nanorods of 50-60 nm length by thermally decomposing at 400 °C the single source precursors Cu 1- x Mg x (OH) 2 . Vegard's laws exist only in the compositional range 0 ≤ x ≤ 0.1, due to the low capacity of the distorted NaCl-type structure to accommodate regular coordination [MgO 6 ] octahedra. Only neutron diffraction allowed the detection of the small amount of MgO nanoparticles present as impurity in a 10 g sample beyond the solubility limit of x = 0.1. In this series, CuO nanorods remain the most active against E. coli and S. aureus with reduction in viability of 99.998% and 98.7% after 180 min in water, respectively. Our synthesis route has significantly increased the activity of pure CuO nanoparticles beyond the values reported so far, especially against E. coli . The bactericidal performances of CuO and the magnesium-substituted counterparts ( i.e. Cu 1- x Mg x O) are not linked to cupric ions they release in water since their mass concentrations after 180 min are much lower than minimal concentrations inhibiting the growth of E. coli and S. aureus . These CuO nanorods kill bacteria in water because they produce a large quantity of free oxygen radicals in the presence of H 2 O 2 only, the majority of which are highly toxic HO˙ radicals. Mg 2+ ions have a detrimental effect on this production, thus explaining the lowest bactericidal performance of Cu 1- x Mg x O nanorods. Definitive knowledge of the toxicity of Cu 1- x Mg x O nanoparticles towards bacteria in water is now available.