Physchem, Volume 2, Issue 4 (December 2022) – 6 articles

Nuclear resonant vibrational spectroscopy (NRVS) is an excellent synchrotron-based vibrational spectroscopy. Its isotope specificity and other advantages are particularly good to study, for example, iron center(s) inside complicated molecules such as enzymes. In order to investigate some small energy shifts, the energy scale variation from scan to scan must be corrected via an in-situ measurement or with other internal reference peak(s) inside the spectra to be calibrated. On the other hand, the energy re-distribution within each scan also needs attention for a sectional scan which has a different scanning time per point in different sections and is often used to measure weak NRVS signals. In this publication, we: (1) evaluated the point-to-point energy re-distribution within each NRVS scan or within an averaged scan with a time-scaled (not energy-scaled) function; (2) discussed the errorbar contributed from the improper “distribution” of ΔE_i or the averaged ΔE within one scan (E_err1) vs. that due to the different ΔE_i from different scans (E_err2). It is well illustrated that the former (E_err1) is as important as, or sometimes even more important than, the latter (E_err2); and (3) provided a procedure to re-calibrate the published NRVS-derived PVDOS spectra in case of need. This article establishes the concept that, at least for sectional NRVS scans, the energy positions should be corrected according to the time scanned rather than be scaled with a universal constant, as in a conventional calibration procedure. Full article

This paper presents the physicochemical characteristics of CeF₃ nanopowder (NP) obtained via electron evaporation. The initial NP was annealed in air (200–500 °C) for 30 min. The annealed NP was evaluated using the following methods: X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), differential scanning calorimetry-thermogravimetry (DSC-TG) and luminescence/magnetic measurements. The degree of cytotoxicity of CeF₃ nanoparticles (NPles) to cell cultures was determined. The cubic phase CeO₂ formed in CeF3 NP after annealing (500 °C). The appearance of the CeO₂ oxide phase led to an increase in the intensity of photoluminescence. Cathodoluminescence was not excited. The paramagnetic response of NPles decreased with an increase in the annealing temperature. Cerium fluoride NPles showed low cytotoxicity towards cancerous and non-cancerous cells. Annealing of the CeF₃ NP at low temperatures led to an improvement in the textural parameters of the not annealed NP. Improved texture parameters indicate the prospect of using CeF₃ as a biomedicine nanocontainer. Full article

The emergence of unexpected properties in two-dimensional materials, interfaces, and nanostructured materials opens an exciting framework for exploring new devices and applications. Recent advances in materials design and the nano structurization of novel, low-dimensional materials, surfaces, and interfaces offer a novel playground to design efficient multifunctional materials-based devices. Low-dimensional materials exhibit peculiarities in their electronic, magnetic, and optical properties, changing with respect to the bulk when they are layered down to a single layer, in addition to their high tunability. Their crystal structure and chemical bonds lead to inherent unique mechanical properties. The fabrication of van der Waals heterostructures by stacking materials with different properties, the better control of interfaces, and the tunability of the physical properties by mechanical strain, and chemical and electronic doping allow for the exploration of multifunctional devices with superconducting, magnetic, and optical properties and unprecedented degrees of freedom in terms of fabrication and tunability. Full article

This work presents the study of the thermal degradation process of two selected polymers: nylon 6 and polyhydroxybutyrate (PHB), representatives of polyamides and polyesters, frequently used nowadays. It is extremely important to specify optimal conditions that would allow a non-toxic and fast reprocessing of polymers in the plastic industry. The Density Functional Theory (DFT) method and a set of various computational details were applied to investigate the influence of the solvent presence and the rise of temperature on the thermodynamics of the degradation process. Obtained results were compared for both of the studied polymers, highlighting observed similarities. External conditions leading to the spontaneity of the nylon 6 thermal degradation process have been estimated. The results described in this paper can be useful in future research works investigating biodegradation conditions of the studied polymers. Full article

CoFe${}_2$O${}_4$ is a promising catalytic material for many chemical reactions. We used ab initio molecular dynamic simulations to study the structure and reactivity of the A- and B-terminations of the low-index CoFe${}_2$O${}_4$(001) surfaces to water adsorption at room temperature. Upon adsorption, water partly dissociates on both termination with a higher dissociation degree on the A-termination (30% versus 19%). The 2-fold coordinated Fe³⁺(tet) in the tetrahedral voids and the 5-fold coordinated Fe³⁺(oct) in the octahedral voids are the main active sites for water dissociation on the A- and B-termination, respectively. Molecular water, hydroxydes, and surface OH resulting from proton transfer to surface oxygens are present on the surfaces. Both water-free surface terminations undergo reconstruction. The outermost Fe³⁺(tet) on the A-termination and B-termination move towards the nearby unoccupied octahedral voids. In the presence of a thin film of 32 water molecules, the reconstructions are partially and completely lifted on the A- and B-termination, respectively. Full article

Plasma ignition in the volume of liquid solution/water initiates the chemical activation of the liquid phase (formation of chemically active particles) and the sputtering of electrode materials, which leads to the formation of nanostructured materials. In this work, the synthesis of structures was carried out by means of underwater plasma excited in water between electrodes composed of different materials. The polarity of the Fe and Cu electrodes was varied at two plasma currents of 0.25 and 0.8 A. The kinetics of the sorption and photocatalysis of three dyes (Rhodamine B, Reactive Red 6C, and Methylene Blue) were studied. According to the results obtained, the polarity of the electrode material has a greater effect on the phase composition than the plasma current. The sorption process can be limiting depending on the type of dye and phase composition. The sorption kinetics can be described by various models at different stages of the process. Photocatalytic studies have shown that the complete decomposition of the three dyes can be achieved in 15–30 min of irradiation. Full article