Direct Synthesis of Mn3[Fe(CN)6]2·nH2O Nanosheets as Novel 2D Analog of Prussian Blue and Material for High-Performance Metal-Ion Batteries.

Rechargeable metal-ion batteries (RMIBs) are prospective highly effective and low-cost devices for energy storage. Prussian blue analogues (PBAs) have become a subject of significant interest for commercial applications owing to their exceptional specific capacity and broad operational potential window as cathode materials for rechargeable metal-ion batteries. However, the limiting factors for its widespread use are its poor electrical conductivity and stability. The present study describes the direct and simple synthesis of 2D nanosheets of MnFCN (Mn3[Fe(CN)6]2·nH2O) on nickel foam (NF) via a successive ionic layer deposition (SILD) method, which provided more ion diffusion and electrochemical conductivity. MnFCN/NF exhibited exceptional cathode performance for RMIBs, delivering a high specific capacity of 1032 F/g at 1 A/g in an aqueous 1M NaOH electrolyte. Additionally, the specific capacitance reached the remarkable levels of 327.5 F/g at 1 A/g and 230 F/g at 0.1 A/g in 1M Na2SO4 and 1M ZnSO4 aqueous solutions, respectively.

An ultra-high-entropy rare earth orthoferrite (UHE REO): solution combustion synthesis, structural features and ferrimagnetic behavior.

A novel ultra-high-entropy rare earth orthoferrite (UHE REO) of Sc1/16Y1/16La1/16Ce1/16Pr1/16Nd1/16Sm1/16Eu1/16Gd1/16Tb1/16Dy1/16Ho1/16Er1/16Tm1/16Yb1/16Lu1/16FeO3 nominal composition was successfully synthesized for the first time through a simple and efficient solution combustion approach. PXRD, Raman, and 57Fe Mössbauer spectroscopy confirmed the high chemical and phase purity of the synthesized UHE REO (hereafter denoted as ΣREFeO3), which belonged to the Pnma space group, typical of the perovskite-like rare earth orthoferrites. Despite the fact that the main X-ray reflections, vibration modes, and spectral Mössbauer components unambiguously indicate the single-phase nature of the sample, the results of SEM and TEM make it possible to establish the presence of a main (about 50 nm) and a minor ultrafine (about 10 nm) fraction of ΣREFeO3 nanoparticles. The bimodal size distribution of nanoparticles was also reflected in the magnetic behavior of this substance: the presence of several sextet components in the Mössbauer spectra, the hard single-domain magnetic nature of the main fraction of 50 nm UHE REO nanoparticles, and the superparamagnetic state of the minor fraction of 10 nm UHE REO nanoparticles. Thus, the unusual features of nanostructured ΣREFeO3 can potentially be used for the creation of new generations of transformers, magnetic memory systems, magnetic screens, radio devices, etc.

Effect of TiO2 Additives on the Stabilization of h-YbFeO3 and Promotion of Photo-Fenton Activity of o-YbFeO3/h-YbFeO3/r-TiO2 Nanocomposites.

Nanostructured hexagonal rare-earth orthoferrites (h-RfeO3, R = Sc, Y, Tb-Lu) are well known as a highly effective base for visible-light-driven heterojunction photocatalysts. However, their application is limited by metastability, leading to difficulties in synthesis due to the irreversible transformation to a stable orthorhombic structure. In this work, we report on a simple route to the stabilization of h-YbFeO3 nanocrystals by the synthesis of multiphase nanocomposites with titania additives. The new I-type heterojunction nanocomposites of o-YbFeO3/h-YbFeO3/r-TiO2 were obtained by the glycine-nitrate solution combustion method with subsequent heat treatment of the products. An increase in the mole fraction of the h-YbFeO3 phase in nanocomposites was found with the titanium addition, indicating its stabilizing effect via limiting mass transfer over heat treatment. The complex physicochemical analysis shows multiple contacts of individual nanocrystals of o-YbFeO3 (44.4-50.6 nm), h-YbFeO3 (7.5-17.6 nm), and rutile r-TiO2 (~5 nm), confirming the presence of the heterojunction structure in the obtained nanocomposite. The photocatalytic activity of h-YbFeO3/o-YbFeO3/r-TiO2 nanocomposites was evaluated by the photo-Fenton degradation of the methyl violet under visible light (λ ≥ 400 nm). It was demonstrated that the addition of 5 mol.% of TiO2 stabilizes h-YbFeO3, which allowed us to achieve a 41.5 mol% fraction, followed by a three-time increase in the photodecomposition rate constant up to 0.0160 min-1.

Ultrasound-assisted co-precipitation synthesis of GdFeO3 nanoparticles: structure, magnetic and MRI contrast properties.

Superparamagnetic nanocrystals of gadolinium orthoferrite (GdFeO3) with close to isometric morphology were successfully synthesized by heat treatment of gadolinium and iron(III) hydroxides obtained by direct co-precipitation with and without ultrasonic irradiation. The obtained samples were investigated by PXRD, low-temperature nitrogen adsorption-desorption isotherm measurements, HRTEM and VSM. It was established that ultrasonication during co-precipitation led to a decrease in the average size of GdFeO3 crystallites obtained after heat treatment by approximately 19%, an increase in their BET specific surface area by more than two times, a decrease in the degree of their aggregation by about five times and an improvement in their magnetic properties due to the increase in phase homogeneity. The colloidal solutions of the GdFeO3 nanoparticles synthesized using ultrasound were investigated by 1H NMR to measure the T1 and T2 relaxation times of water protons at 0.47 T. The resulting relaxivities r1 and r2 were approximately recalculated at 1.5, 3 and 4.7 T on the basis of a semi-statistical ad hoc method by analyzing the literature data for a number of structurally similar compounds with reported relaxivity values at different NMR frequencies. According to the experimental and predicted values of the r2/r1 ratio, the investigated GdFeO3 sample may be classified as a T1-contrast agent for MRI at 0.47 and 1.5 T, as a T1-T2 dual-modal contrast agent at 3 T and as a T2-contrast agent at 4.7 T.

Correction: Catalyst supports based on ZnO-ZnAl2O4 nanocomposites with enhanced selectivity and coking resistance in isobutane dehydrogenation.

Correction for 'Catalyst supports based on ZnO-ZnAl2O4 nanocomposites with enhanced selectivity and coking resistance in isobutane dehydrogenation' by Anna N. Matveyeva et al., Dalton Trans., 2022, 51, 12213-12224, https://doi.org/10.1039/d2dt02088b.

Size-Dependent Structural, Magnetic and Magnetothermal Properties of Y3Fe5O12 Fine Particles Obtained by SCS.

Iron-containing oxides are the most important functional substance class and find a tremendous variety of applications. An attractive modern application is their use in biomedical technologies as components in systems for imaging, drug delivery, magnetically mediated hyperthermia, etc. In this paper, we report the results of the experimental investigation of submicron Y3Fe5O12 garnet particles obtained in different sizes by solution combustion synthesis (SCS) using glycine organic fuel to discuss the interdependence of peculiarities of the crystal and magnetic structure and size's influence on its functional magnetothermal performance. A complex study including Mössbauer and Raman spectroscopy accompanied by X-ray diffractometry, SEM, and measurements of field and temperature magnetic properties were performed. The influence of the size effects and perfectness of structure on the particle set magnetization was revealed. The ranges of different mechanisms of magnetothermal effect in the AC magnetic field were determined.

Catalyst supports based on ZnO-ZnAl2O4 nanocomposites with enhanced selectivity and coking resistance in isobutane dehydrogenation.

Development of coking resistant supports and catalysts for hydrocarbons conversion is challenging, especially when using such acidic materials as alumina. Apparently, this problem can be mitigated by using spinels that are less acidic, being, however, thermally stable. In this study, a series of ZnO-ZnAl2O4 nanocomposites with different ZnO loading were prepared by urotropine-nitrate combustion synthesis to be used as supports for isobutane dehydrogenation catalysts. The nanocomposites were characterized by XRD, SEM, N2-physisorption analysis, EDS, H2-TPR, TPD of NH3 and tested in isobutane dehydrogenation. Spinels with small amounts of ZnO displayed higher acidity and specific surface areas than samples with a higher ZnO content (30-40 mol%). At the same time, the maximum activity and the lowest selectivity to by-products (CH4 and C3H6) after 10 min of the reaction were observed for the nanocomposite containing 20 mol% of ZnO. The obtained nanocomposites have demonstrated better resistance to coking compared to commercial alumina.

The PentUnFOLD algorithm as a tool to distinguish the dark and the light sides of the structural instability of proteins.

Intrinsically disordered proteins are frequently involved in important regulatory processes in the cell thanks to their ability to bind several different targets performing sometimes even opposite functions. The PentUnFOLD algorithm is a physicochemical method that is based on new propensity scales for disordered, nonstable and stable elements of secondary structure and on the counting of stabilizing and destabilizing intraprotein contacts. Unlike other methods, it works with a PDB file, and it can determine not only those fragments of alpha helices, beta strands, and random coils that can turn into disordered state (the "dark" side of the disorder), but also nonstable regions of alpha helices and beta strands which are able to turn into random coils (the "light" side), and vice versa (H ↔ C, E ↔ C). The scales have been obtained from structural data on disordered regions from the middle parts of amino acid sequences only, and not on their expectedly disordered N- and C-termini. Among other tendencies we have found that regions of both alpha helices and beta strands that can turn into the disordered state are relatively enriched in residues of Ala, Met, Asp, and Lys, while regions of both alpha helices and beta strands that can turn into random coil are relatively enriched in hydrophilic residues, and Cys, Pro, and Gly. Moreover, PentUnFOLD has the option to determine the effect of secondary structure transitions on the stability of a given region of a protein. The PentUnFOLD algorithm is freely available at http://3.17.12.213/pent-un-fold and http://chemres.bsmu.by/PentUnFOLD.htm .