A Review on Synthesis of 2-Dimensional Mn+1X (MXene) materials

The sequence of 2D transition metal carbides, carbonitrides, and nitrides has gained a lot of interest since the discovery of Ti3C2. About thirty new MXene compounds have been identified, with eight different MXene synthesis methods. The presence of surface terminations such as hydroxyl, oxygen, fluorine, or chlorine in the materials described thus far indicates strong hydrophilicity as well as metallic conductivity MXenes are becoming increasingly popular due to their diverse chemistry, which has sparked a surge in academic interest. We will study and examine the many methods of fabricating MXenes in this review, which will cover everything from MAX phase etching to exfoliation, as well as the best approach to synthesise them and their most current applications.

SYNTHESIS AND STUDY OF Zn COMPLEXES WITH N'-ACYL-SALICYLHYDRAZIDES

Zn complexes with potentially tridentate (carbonyl and hydroxyl oxygen atoms of the salicylic fragment and nitrogen atom of the amide group) were synthesized by the ligand N'-phthalimido-salicylamide (H2L) and potentially heptadentate (carbonyl and hydroxyl oxygen atoms of the salicylic fragment, two nitrogen atoms of the hydrazide moiety and two oxygen atoms of the carbonyl and carboxyl groups of the maleic fragment) with the ligand N'-maleoal-salicylhydrazide (H4L) with 78% and 86% yield, respectively. The structural features of the N'-phthalimido-salicylamide (H2L) and N'-maleoyl-salicylhydrazide (H4L) obtained were established by IR and 1H and 13C NMR spectroscopy. In the 1H NMR spectra, signals from proton-containing groups are detected in the expected region. Also the structure of the ligands confirms 13C NMR spectroscopy. The yield of ligands is 92% and 95%, respectively. It was found that both ligands, in the conducted synthesis reactions, behave as bidentate, are in the enol form. Ligand-N- (salicylamide) -phthalimide is coordinated with zinc ion through the oxygen atoms of the phenol and nitrogen amide groups. The N’-maleoyl-salicylhydrazide ligand is coordinated with the zinc ion through the oxygen atoms of the salicylic residue and the nitrogen atom of the amide group of the maleic residue. The structures of synthesized Zn coordination compounds with H2L and H4L have been studied by IR and electronic absorption spectrometry, elemental analysis and thermogravimetry. These analyzes helped to establish that the metal ion in complex compounds is bound to two water molecules by a hydrogen bond and forms a distorted octahedral geometry. Coordination with water molecules is also confirmed by the TG curves, in which the first and second stages of weight loss are attributed to the removal of solvent molecules — coordinated water molecules and DMF.

Hydrothermal Synthesis of Rare-Earth Modified Titania: Influence on Phase Composition, Optical Properties, and Photocatalytic Activity

In order to expand the use of titania indoor as well as to increase its overall performance, narrowing the band gap is one of the possibilities to achieve this. Modifying with rare earths (REs) has been relatively unexplored, especially the modification of rutile with rare earth cations. The aim of this study was to find the influence of the modification of TiO2 with rare earths on its structural, optical, morphological, and photocatalytic properties. Titania was synthesized using TiOSO4 as the source of titanium via hydrothermal synthesis procedure at low temperature (200 °C) and modified with selected rare earth elements, namely, Ce, La, and Gd. Structural properties of samples were determined by X-ray powder diffraction (XRD), and the phase ratio was calculated using the Rietveld method. Optical properties were analyzed by ultraviolet and visible light (UV-Vis) spectroscopy. Field emission scanning electron microscope (FE-SEM) was used to determine the morphological properties of samples and to estimate the size of primary crystals. X-ray photoelectron spectroscopy (XPS) was used to determine the chemical bonding properties of samples. Photocatalytic activity of the prepared photocatalysts as well as the titania available on the market (P25) was measured in three different setups, assessing volatile organic compound (VOC) degradation, NOx abatement, and water purification. It was found out that modification with rare earth elements slows down the transformation of anatase and brookite to rutile. Whereas the unmodified sample was composed of only rutile, La- and Gd-modified samples contained anatase and rutile, and Ce-modified samples consisted of anatase, brookite, and rutile. Modification with rare earth metals has turned out to be detrimental to photocatalytic activity. In all cases, pure TiO2 outperformed the modified samples. Cerium-modified TiO2 was the least active sample, despite having a light absorption tail up to 585 nm wavelength. La- and Gd-modified samples did not show a significant shift in light absorption when compared to the pure TiO2 sample. The reason for the lower activity of modified samples was attributed to a greater Ti3+/Ti4+ ratio and a large amount of hydroxyl oxygen found in pure TiO2. All the modified samples had a smaller Ti3+/Ti4+ ratio and less hydroxyl oxygen.

A DFT study on the effect of oxygen vacancies and H2O in Mn-MOF-74 on SCR reactions

The carboxyl and hydroxyl oxygen vacancies in Mn-MOF-74 can not only activate the reaction species, but also promote the desorption of NO2 molecules from metal sites for the subsequent rapid SCR reactions.

Halogen-bonded cocrystals ofN-salicylidene Schiff bases and iodoperfluorinated benzenes: hydroxyl oxygen as a halogen bond acceptor

Novel halogen bondedo-hydroxy imine cocrystals with 1,3,5-triiodotrifluoro-benzene and 1,2-, 1,3- and 1,4-diiodotetrafluorobenzene have been synthesized.

Investigating the mechanism of catalytic reduction of silver nitrate on the surface of barium titanate at room temperature: oxygen vacancies play a key role

The oxygen vacancies on BaTiO3 surface linked with the hydroxyl oxygen of ethylene glycol and catalyzed the reduction of AgNO3.

Synthesis, X-Ray Structure, and Characterization ofCatena-bis(benzoate)bis{N,N-bis(2-hydroxyethyl)glycinate}cadmium(II)

The reaction of -bis(2-hydroxyethyl)glycine (bicine; ) with in MeOH yielded the polymeric compound . The complex crystallizes in the tetragonal space group . The lattice constants are and Å. The compound contains chains of repeating units. One atom is coordinated by two carboxylate oxygen, four hydroxyl oxygen, and two nitrogen atoms from two symmetry-related 2.21111 (Harris notation) ligands. The other atom is coordinated by six carboxylate oxygen atoms, four from two ligands and two from the monodentate benzoate groups. Each bicinate(-1) ligand chelates the 8-coordinate, square antiprismatic atom through one carboxylate oxygen, the nitrogen, and both hydroxyl oxygen atoms and bridges the second, six-coordinate trigonal prismatic center through its carboxylate oxygen atoms. Compound1is the first structurally characterized cadmium(II) complex containing any anionic form of bicine as ligand. IR data of1are discussed in terms of the coordination modes of the ligands and the known structure.