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![Second coordination spheres of titanium cations within (a) Ti(III)p, (b) Ti(IV)p, and (c) TiP 2 O 7 . The [P 2 O 7 ] 4− group, which is connected via two coordination sites, is marked in green.](publication/356449026/figure/fig8/AS:1094649343148040@1637996149793/Second-coordination-spheres-of-titanium-cations-within-a-TiIIIp-b-TiIVp-and-c.png)
Second coordination spheres of titanium cations within (a) Ti(III)p, (b) Ti(IV)p, and (c) TiP 2 O 7 . The [P 2 O 7 ] 4− group, which is connected via two coordination sites, is marked in green.
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Transition-metal phosphates show a wide range of chemical compositions, variations of the valence states, and crystal structures. They are commercially used as solid-state catalysts, cathode materials in rechargeable batteries, or potential candidates for proton-exchange membranes in fuel cells. Here, we report on the successful ab initio structure...
Citations
... The composition, crystal structure and chemical properties of tetravalent metal phosphates (M(IV)) have received particular attention from chemists since the middle of the 20th century due to their broad range of applications including catalysis, waste water treatment, energy storage etc. [1][2][3][4][5][6][7] . Recently, the results of some early works have been refined using new experimental techniques to assess the composition and crystal structure of known M(IV) phosphates 1 . ...
A previously unknown double ceric sodium phosphate hydrate Na1.97Ce1.03(PO4)2 ⋅ xH2O containing both ceric and cerous cations was obtained by the hydrothermal treatment of amorphous ceric phosphate mixed with a sodium hydroxide aqueous solution. The presence of Ce³⁺ in the structure was proved by HERFD‐XANES and ESR spectroscopy. Iterative transformation factor analysis of HERFD‐XANES data allowed estimating the content of Ce³⁺ as 10 % of the total cerium. Water content of x=0.55 has been determined by thermogravimetric analysis combined with mass‐spectrometry data. The structure of the compound was solved from powder X‐ray diffraction data (S.G. P21/c a=6.9441(2) Å, b=11.6805(3) Å, c=9.3434(3) Å, β=111.6827(18)°). The new ceric sodium phosphate hydrate has a tunnel structure, where Ce³⁺ cations most likely partially occupy Na⁺ positions. The crystal structure of the novel compound has no direct analogues among the crystal structures of double tetravalent metal phosphates.
... They also show high depletion of Ca, Si, Al and Na, as well as O, suggesting that these phases consist mostly of Ti, as also inferred from the XRD analysis (Fig. 2b). Some of the Ti-enriched zones also contain P, which probably forms as a result of the preferential formation of coordinated structures of transition-metal phosphates with Ti in the liquid state 17 . The residual glassy matrix of this sample, present between the different phases, has a chemical composition similar to that of the sample reduced for 1 min. ...
Red mud is the waste of bauxite refinement into alumina, the feedstock for aluminium production1. With about 180 million tonnes produced per year1, red mud has amassed to one of the largest environmentally hazardous waste products, with the staggering amount of 4 billion tonnes accumulated on a global scale1. Here we present how this red mud can be turned into valuable and sustainable feedstock for ironmaking using fossil-free hydrogen-plasma-based reduction, thus mitigating a part of the steel-related carbon dioxide emissions by making it available for the production of several hundred million tonnes of green steel. The process proceeds through rapid liquid-state reduction, chemical partitioning, as well as density-driven and viscosity-driven separation between metal and oxides. We show the underlying chemical reactions, pH-neutralization processes and phase transformations during this surprisingly simple and fast reduction method. The approach establishes a sustainable toxic-waste treatment from aluminium production through using red mud as feedstock to mitigate greenhouse gas emissions from steelmaking.
... [40] It was demonstrated in previous studies that the PBE-TS functional accurately reproduces crystal structure data of neutral-framework zeotypes, [41,42] and good agreement with experimental vibrational spectra was observed in investigations of a hydrated aluminophosphate [43] and of two titanium pyrophosphates. [44] The calculations used a plane-wave cutoff energy of 700 eV and on-the-fly ultrasoft pseudopotentials. Due to the presence of V 4 + cations, spin-polarized calculations were carried out for all systems under study: On the one hand, two fully ordered models of VSH-2Cs (space groups Cmc2 1 and Cm2a, see 2.2) were compared, optimizing all atomic coordinates, but fixing the cell parameters to experimental values. ...
The accessibility of lithium cations in microporous vanadosilicate VSH‐2Cs of composition Cs2(VO)(Si6O14) ⋅ 3H2O was investigated by Single Crystal X‐ray Diffraction, Attenuated Total Reflection Fourier Transformed Infrared Spectroscopy and Density Functional Theory calculations. The topological symmetry of VSH‐2Cs is described in space group Cmca. After Li‐ion exchange, the structure of VSH‐2Li adopted monoclinic symmetry (space group C2/c) with a=17.011(2) Å, b=8.8533(11) Å, c=12.4934(16) Å, β=91.677(4)°, V=1880.7(4) ų. The strong interactions between Li ions and oxygen‐framework atoms drive the main deformation mechanism, which is based on cooperative rotation of SiO4 and VO5 units around their oxygen atoms that behave as hinges. Exchange of Cs⁺ by Li⁺ is incomplete and accompanied by the formation of protonated species to counterbalance the electrostatic charge. The incorporation of protons is mediated by the presence of water dimers in the structural channels. H2O molecules in VSH‐2Li account not only as “space‐fillers” after the removal of large Cs ions but also mediate proton transfer to compensate the negative charge of the host vanadosilicate framework.
... For Zn3(PO4)2·4H2O, the maximum of the long-wave band corresponds to the frequency of 3280 cm -1 ; for phosphates, in which half of the octahedral are filled with cobalt (Zn2.5Со0.5(PO4)2·4H2O), a broad maximum of 3180-3300 cm -1 is noted; replacing zinc with cobalt in all octahedral positions (Zn2Со(PO4)2·4H2O) leads to a shift of ν(ОН) to a frequency of 3150 cm -1 . A similar effect is also mentioned in the study (Petersen et al., 2022;Wu et al., 2015). ...
... At the same time, the difference in the charge of OH-groups in the same water molecule also increases ( Table 2). This is consistent with work (Grabowski, 2016) and is explained by the stronger polarizing effect of cobalt on water molecules that make up the nearest coordination environment of the cation (Petersen et al., 2022). ...
... Quite significant splitting of the main absorption bands of the phosphate anion, the appearance of fully symmetric oscillation v1(A1) -940, 930 cm -1 and v2 (Е) -500 and 420 cm -1 , usually inactive in IR spectra (Koleva et al., 2018), indicates significant distortions of the tetrahedron in the lattice zinc-cobalt phosphates. This is confirmed by the data of X-ray structural analysis and the interaction of anions with each other due to the presence of hydrogen bonds (Petersen et al., 2022). ...
Nadiia Antraptseva, Olena Podobii, Galyna Bila Determination of food additive zinc-cobalt(II) phosphate form resistant to high temperatures 10.24263/2304-974X-2023-12-2-10 http://nuft.edu.ua/doi/doc/ufj/2023/2/10.pdf
... The presence of the peaks at 504.5 and 1083 cm −1 could be assigned due to the asymmetric stretching of the Si-O-Si unit [41]. The peak at 627 cm −1 signified Ti-O-Ti [42], and the peaks at 485, 515, and 1125 cm −1 signified the presence of the Si-O-Ti moiety [43]. ...
Selective oxidation of organics over an efficient heterogeneous catalyst under mild liquid phase conditions is a very demanding chemical reaction. Herein, we first report the modification of the surface of mesoporous silica MCM-41 material by phosphate for the efficient incorporation of Ti(IV) in the silica framework to obtain highly ordered 2D hexagonal mesoporous material STP-1. STP-1 has been synthesized by using tetraethyl orthosilicate, triethyl phosphate, and titanium isopropoxide as Si, P, and Ti precursors, respectively, in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) under hydrothermal conditions. The observed specific surface area and pore volume of STP-1 were 878 m2g−1 and 0.75 ccg−1, respectively. Mesoporous STP-1 has been thoroughly characterized by XRD, FT-IR, Raman spectroscopy, SEM, and TEM analyses. Titanium incorporation (Ti/Si = 0.006) was confirmed from the EDX analysis. This mesoporous STP-1 was used as a heterogeneous catalyst for the selective oxidation of styrene into benzaldehye in the presence of dilute aqueous H2O2 as an oxidizing agent. Various reaction parameters such as the reaction time, the reaction temperature, and the styrene/H2O2 molar ratio were systematically studied in this article. Under optimized reaction conditions, the selectivity of benzaldehyde could reach up to 93.8% from styrene over STP-1. Further, the importance of both titanium and phosphate in the synthesis of STP-1 for selective styrene oxidation was examined by comparing the catalytic result with only a phosphate-modified mesoporous silica material, and it suggests that both titanium and phosphate synergistically play an important role in the high selectivity of benzaldehyde in the liquid phase oxidation of styrene.
... Among Particularly important are the hybrid compounds investigated, organic phosphates formed as a result of the inorganic oxy-acid reaction such as orthophosphoric acid (H3PO4) and organic amines. Organic monohydrogen (HPO4 2-) and dihydrogen phosphate (H2PO4-) compounds provide a class of materials with numerous practical and potential uses in various fields such as biomolecular sciences, catalysis, and liquid crystal-material development, ferroelectrics, nonlinear optical and supramolecular studies [2,4]. ...
... . The lattice and unit cell parameters are a= 8.8040 (3) Å, b= 10.4220 (4) Å, c= 14.0890 (6) Å, α= 86.418(2), and β= 75.8890(19) °. In this crystal structure, the existence of the hydrogen phosphate anion is verified by the P -O bond distances, and the presence of a related density peak at a distance from the oxygen atom O 1 confirms the anion hydroxyl group. ...
The present work focuses on the Anilinium dihydrogen phosphate [ADHP]. Quantum chemistry and Hirshfeld surface analyses are used in the study.This work was carried out to investigate and quantify the contributions and the various intermolecular interactions within crystals. This analysis reveals that O…H and H…H, the intermolecular interactions in the compound, were studied using Hirshfeld surface analysis. These results show that both compounds exhibit similar features, however, the energy gap between EHOMO and ELUMO obtained from the molecular orbital analysis indicates that compound ADHP is analyzed by a molecular structural more favorable for charge transfer, The Mulliken Atomic Charges and Density of state (DOS).
Nanocomposites of titanium dioxide (TO) and titanium pyrophosphate (TPO) have attracted a considerable attention over the past several decades due to their optical properties and high ratio of surface/volume. TO/TPO and Ag/TO/TPO nanocomposites were prepared by electrochemical techniques, followed by electroless deposition of silver. The nanocomposites were discussed by FESEM, TEM, XRD, XPS, FT-IR, Raman, and UV–Vis spectroscopy. XRD and TEM revealed the nanoparticle size of the two composites. Glassy carbon-modified electrode by TO/TPO gave better response than Ag/TO/TPO for the electro-analysis of Pb(II) and Hg(II) as observed by the anodic stripping technique where the detection limit values were 3.09 and 7.46 for Pb(II) and Hg(II), respectively. It was found that the Ag/TO/TPO@GC exhibits an improved sensitivity for the determination of both Pb(II) and Hg(II) ions simultaneously. The presence of O–P–O, Ti–O bonds and the absence of Ti–P were an evidence of the replacement of P atom to Ti atom in their lattice which resulted in forming oxygen vacancies that develop the electrochemical characteristics of the nanocomposite. A slight extension of the absorption edges of TO/TPO into the visible region and a decrease in the band gap gave TO/TPO superior photocatalytic activity for the degradation of methylene blue dye with extent of 99% and a first-order reaction with rate constant 0.01 min⁻¹.
Синтезированы сорбенты на основе фосфатов Ti-Ca-Mg, изучены их физико-химические и сорбционные свойства по отношению к Cs(I), Sr(II), Co(II) (в виде как стабильных ионов, так и радионуклидов 137 Cs, 60 Co, 90 Sr). Образцы TiCaMg-1 и TiCaMg-2 получали путем гетерогенного взаимодействия кислых и средних фосфатов Ca-Mg с раствором сульфата титанил-диаммония, а образец TiCaMg-3 - термообработанного доломита с предварительно осажденной суспензией кислого фосфата титана. Показано, что полученные образцы обладают высоким сродством к ионам Cs + , Sr 2+ , Co 2+ и их радионуклидам. Образец TiCaMg-3 имеет наиболее высокие значения коэффициента распределения радионуклидов 137 Cs, 60 Co и 90 Sr (>10 5 см 3 /г). Установлено, что различие в свойствах композитов обусловлено их фазовым и химическим составом, а также текстурными характеристиками (удельная поверхность, сорбционный объем и размер пор). Сорбент TiCaMg-3 характеризуется наибольшим сорбционным объемом (0.410 см 3 /г) и средним диаметром пор (10.2 нм), что обеспечивает лучшую доступность ионогенных групп при обменных реакциях.
