A Bent Tb2C2 Cluster Encaged in a CS (6)-C82 Cage: Synthesis,Isolation and X-ray Crystallographic Study

Terbium (Tb)-based dimetallofullerene, Tb₂C₈₄, has been synthesized and isolated by multistep HPLC. According to the UV-vis-NIR spectroscopic characterization and comparison with the reported analogous M₂C₈₄ (M = Sc, Y) metallofullerenes, the molecular structure of Tb₂C₈₄ is proposed to be Tb₂C₂@C_s (6)-C₈₂ featuring a metal carbide clusterfullerene (CCF) structure, which is unambiguously confirmed by X-ray crystallographic study. A detailed analysis of the crystal structure of a cocrystal of Tb₂C₂@C_s (6)-C₈₂·Ni^II(OEP)·2C₆H₆ (Ni^II(OEP) = nickel (II) octaethylporphyrin) reveals that a bent Tb₂C₂ carbide cluster is encaged rigidly inside a C_s (6)-C₈₂ cage. The C-C bond within the encaged Tb₂C₂ carbide cluster behaves as a typical C-C triple bond. The asymmetric unit in Tb₂C₂@C_s (6)-C₈₂·Ni^II(OEP)·2C₆H₆ contains two fullerene sites, for which the encaged Tb₂C₂ carbide cluster however locates at nearly the same position with one Tb atom being beneath a hexagon and another Tb atom pointing to the conjunction of two adjacent hexagons.     

Isolation and Crystallographic Characterization of Tm3N@D2 (35)-C88

Tm₃N@D₂(35)-C₈₈ has been prepared by vaporization of graphite rods doped with Tm₂O₃, graphite powder, and iron nitride in a Krätschmer-Huffman arc-discharge fullerene generator and isolated by high pressure liquid chromatography. A single crystal X-ray diffraction study reveals the dimensions of the D₂(35)-C₈₈ cage and the positioning of the Tm₃N unit inside.     

Phase diagrams of the ternary liquid systems [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2] and [Ce(NO3)3(TBP)3]-C10H22-[Th(NO3)4(TBP)2] and of the quaternary liquid system [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2]-[Th(NO3)4(TBP)2]

The phase diagrams of the ternary liquid systems [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂(TBP)₂] and [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[Th(NO₃)₄(TBP)₂] and of the quaternary liquid system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂(TBP)₂]-[Th(NO₃)₄(TBP)₂] at T = 298.15 K are constructed. The phase diagrams are characterized by areas of homogeneous solutions and of two-phase liquid systems (systems with phase separation), with one phase (I) enriched in [Ce(NO₃)₃(TBP)₃], [Th(NO₃)₄(TBP)₂], and [UO₂(NO₃)₂(TBP)₂], and the other phase (II), in C₁₀H₂₂. Using the data on the mutual solubility of the components in the systems under consideration and equations of the NRTL model, the parameters of intermolecular interactions and the excess Gibbs energies (G ^ex) were calculated for the binary, ternary, and quaternary systems. Passing from the ternary system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[Th(NO₃)₄(TBP)₂] to the quaternary system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂ (TBP)₂]-[Th(NO₃)₄(TBP)₂] does not appreciably affect the distribution of C₁₀H₂₂ between phases I and II, but leads to the redistribution of [Ce(NO₃)₃(TBP)₃] into phase II and of [Th(NO₃)₄(TBP)₂] into phase I.     

Stabilization of IPR open-shell fullerenes C74 (D3h) and C76 (Td) in radical addition reactions

The analysis of previously experimentally obtained and characterized by X-ray perfluoralkyl derivatives C₇₄(D_3h)(CF₃)₁₂ and C₇₆(T_d)(CF₃)₁₂ have shown for the first time that the most feasible positions of addends are phenalenyl-radical substructures and/or hexagons with delocalized pi-bonds, that lead to stabilization of these molecules. The most probable addition positions of H^? and CF₃^? radicals to the «missing» fullerenes С₇₄ (D_3h) and С₇₆ (T_d) are revealed on the basis of developed approach of molecular modeling followed by DFT calculations. Radical addition reactions seem to be useful for stabilization of open-shell fullerenes.     

Calculations of the water-dimer encapsulations into C84

The water-dimer formation and its encapsulation into D₂(22)-C₈₄ and D_2d(23)-C₈₄ fullerenes is evaluated. The water-dimer populations are computed using the potential-energy change from the G3 theory and anharmonic partition functions from the MP2/AUG-cc-pVQZ approach. The encapsulation energetics is treated at the M06-2X/6-31++G** level and it is found that the water-dimer storage in C₈₄ is attractive, yielding an energy gain of more than 10 kcal mol^?1. This substantial encapsulation energy together with the computed temperature increase of the water-dimer population in the saturated steam suggests that the (H₂O)₂@C₈₄ endohedrals could be produced in a high-temperature/high-pressure approach similarly to encapsulation of rare gases in fullerenes.     

Computations on Metallofullerenes Derivatized during Extraction: La@C80-C6H3Cl2 and La@C82-C6H3Cl2

Recently, an extraction of la metallofullerenes from soot using 1,2,4-trichlorobenzene has been reported for La@C₈₀ and La@C₈₂. In both cases, the cages were derivatized by the solvent (forming La@C₈₀-C₆H₃Cl₂ and La@C₈₂-C₆H₃Cl₂) and the following X-ray analysis disclosed rather unexpected cages: C₈₀(C _2v ;3) and C₈₂(C _3v ;7). In order to explain the challenging observations, a two-step computational treatment is presented. The first step deals with the high-temperature gas-phase formation of the underivatized endohedrals while the second step models the reaction with the solvent. The Gibbs free energies were evaluated for representative temperatures and the computational scheme was able to confirm high relative populations for the observed derivatized cages.     

Durability of Na2O-RO-SiO2 glasses in water

The effect of divalent cation ions on chemical durability was studied in the base glasses 16Na₂O-1ORO-74SiO₂. In order to keep the same surface area, a fixed volume of glass powder was exposed to the corroding action of water. The amount of SiO₂ and alkali extracted was determined. The chemical durability of glass was found to increase with increasing bond strength between the divalent cation and the non-bridging oxygen ion.     

Electrochemical synthesis and physicochemical study of lanthanum(III) acetylacetonate complexes

Anodic dissolution of lanthanum metal in the presence of acetylacetone in ethanol, acetonitrile, and water was studied. Adducts of lanthanum tris--diketonates [La(EtOH)_0.5(AA)₃], [La(HAA)(AA)₃], and La(AA)₃(H₂O)₄, respectively, were isolated from these solutions. Electrochemical oxidation of lanthanum in the course of electrolysis is accompanied by its chemical dissolution. The compositions of the compounds obtained were confirmed by IR spectroscopy, mass spectrometry, thermal gravimetric analysis, isothermal heating, and elemental analysis for metal.Translated from Radiokhimiya, Vol. 46, No. 6, 2004, pp. 510–512.Original Russian Text Copyright © 2004 by Kostyuk, Dik, Tereshko, Trebnikov.     

Violet Antimony Phosphorus with Enhanced Photocatalytic Hydrogen Evolution (Small 41/2023)

Violet phosphorus (VP), a recently confirmed layered elemental structure, is demonstrated to have unique photoelectric, mechanical, and photocatalytic properties. Element substitution plays a significant role in modifying the physical/chemical properties of semiconducting materials. Herein, antimony is adopted to substitute some phosphorus atoms in VP crystals to tune their physical and chemical properties, resulting in a significantly enhanced photocatalytic hydrogen evolution performance. The antimony-substituted violet phosphorus single crystal (VP-Sb) is synthesized and characterized by single crystal X-ray diffraction (CSD-2214937). The bandgap of VP-Sb has been found to be lowered from that of VP by UV/vis diffuse reflectance spectroscopy and density-functional theory (DFT) calculation, enhancing the optical absorption during photocatalytic reaction. The conducting band minimum of VP-Sb is found to be upshifted from that of VP from measurements and calculation, enhancing its hydrogen reduction activity. The valance band maximum is found to be lowered to weaken its oxidation activity. The edge of VP-Sb is calculated to have an excellent H^* adsorption–desorption performance and superior H₂ generation kinetics. The H₂ evolution rate of VP-Sb is demonstrated to be significantly enhanced to be 1473 µmol h⁻¹ g⁻¹, about five times of that of pristine VP (299 µmol h⁻¹ g⁻¹) under the same experimental conditions.     

A Robust n-n Heterojunction: Cu?N and B?N Boosting for Ambient Electrocatalytic Nitrogen Reduction to Ammonia

An n-n type heterojunction comprising with Cu N and B N dual active sites is synthesized via in situ growth of a conductive metal–organic framework (MOF) [Cu₃(HITP)₂] (HITP = 2,3,6,7,10,11-hexaiminotriphenylene) on hexagonal boron nitride (h-BN) nanosheets (hereafter denoted as Cu₃(HITP)₂@h-BN) for the electrocatalytic nitrogen reduction reaction (eNRR). The optimized Cu₃(HITP)₂@h-BN shows the outstanding eNRR performance with the NH₃ production of 146.2 µg h⁻¹ mg_cat⁻¹ and the Faraday efficiency of 42.5% due to high porosity, abundant oxygen vacancies, and Cu N/B N dual active sites. The construction of the n-n heterojunction efficiently modulates the state density of active metal sites toward the Fermi level, facilitating the charge transfer at the interface between the catalyst and reactant intermediates. Additionally, the pathway of NH₃ production catalyzed by the Cu₃(HITP)₂@h-BN heterojunction is illustrated by in situ FT-IR spectroscopy and density functional theory calculation. This work presents an alternative approach to design advanced electrocatalysts based on conductive MOFs.     

One-step oxidative-adsorptive desulfurization of DBT on simulated solar light-driven nano photocatalyst of MoS2-C3N4-BiOBr @MCM-41

Using a catalyst-adsorbent for simultaneous oxidation and adsorption of sulphuric compounds in liquid fuels is an effective and economical way. Thus in this paper, the core–shell MoS₂-C₃N₄-BiOBr@MCM-41 photocatalyst-adsorbents with different percentages of MoS₂ (1, 3, and 5 wt%) were prepared and used in a one-step photo oxidative-adsorptive desulfurization under simulated solar light. The samples were characterized by XRD, FESEM, FTIR, EDX, BET-BJH, TEM, UV–Vis DRS, and PL analyses. The results indicated that the final C/C₀ decreased from 0.42 to 0.016 with increasing the MoS₂ percentage (98.4% conversion). Despite the lowest surface area (845 m²/g) and the broad bandgap energy (2.8 eV), the sample with 5 wt% of MoS₂ illustrated the most degree of desulfurization due to strong interaction between components, the highest coverage of MCM-41 with active phases, high population of structural defects, high capability of light absorption and low recombination rate of charge carriers. GC-MS analysis indicated no DBT, DBTO or DBTO₂ in the treated fuel. However, the presence of DBTO₂ on the surface of the photocatalyst was confirmed that reveals the successful one-step oxidative-adsorptive desulfurization on the MoS₂-C₃N₄-BiOBr@MCM-41. The adsorption mechanism was consistent with the pseudo-second-order kinetics, indicating that the rate-limiting step was chemical adsorption. Moreover, selectivity evaluations showed that while MoS₂-C₃N₄-BiOBr@MCM-41 photocatalyst had high activity in the desulfurization of DBT, its affinity for adsorption and photocatalytic oxidation of non-sulfur aromatic compounds such as benzene, xylene and toluene was very low.     

Citrate gel synthesis and characterization of (ZrO2)0.85(REO1.5)0.15 (RE = Y, Sc) solid solutions

By the citrate gel method, (ZrO₂)_0.85(REO_1.5)_0.15 (RE = Y, Sc) solid solutions in pure cubic fluorite structure were prepared at relatively low calcination temperatures. The existence of the strong coordination interaction between the COO⁻ groups of the ligands and metal ions could effectively prevent the segregation of metal ions during the gel formation. Upon heat treatment within 110-500 °C, the gel decomposed by multi-steps, with the formation of well-defined intermediate decomposition products, while, the bonding nature between COO⁻ groups and metal ions changed with temperature: unidentate (110-250 °C) → bridging (300-350 °C) → ionic (400-500 °C). The oxide powder resulted from the calcination of the gel at 800 °C is an assembly of mesoporous nanoparticles with uniform sizes, but agglomerated in lumps. It was confirmed that the chemical homogeneity, nanoparticle size uniformity and crystallinity, sinterability and electrical conductivity of (ZrO₂)_0.85(REO_1.5)_0.15 can be remarkably improved by avoiding the phase separation (solid/liquid) phenomenon during the preparation of the gels.     

Porous BN Nanofibers Enable Long‐Cycling Life Sodium Metal Batteries

Sodium metal anode, featuring high capacity, low voltage and earth abundance, is desirable for building advanced sodium‐metal batteries. However, Na‐ion deposition typically leads to morphological instability and notorious chemical reactivity between sodium and common electrolytes still limit its practical application. In this study, a porous BN nanofibers modified sodium metal (BN/Na) electrode is introduced for enhancing Na‐ion deposition dynamics and stability. As a result, symmetrical BN/Na cells enable an impressive rate capability and markedly enhanced cycling durability over 600 h at 10 mA cm^?2. Density functional theory simulations demonstrate BN could effectively improve Na‐ion adsorption and diffusion kinetics simultaneously. Finite element simulation clearly reveals the intrinsic smoothing effect of BN upon multiple Na‐ion plating/stripping cycles. Coupled with a Na₃V₂O₂(PO₄)₂F/Ti₃C₂X cathode, sodium metal full cells offer an ultrastable capacity of 125/63 mA h g^?1 (≈420/240 Wh kg^?1) at 0.05/5 C rate over 500 cycles. These comprehensive analyses demonstrate the feasibility of BN/Na anode for the establishment of high‐energy‐density sodium‐metal full batteries.     

Synthesis and properties of A6B2(OH)16Cl2·4H2O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) materials for environmental applications

Double layered hydroxide materials of composition A₆B₂(OH)₁₆Cl₂·4H₂O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) were synthesized by chemical precipitation at 60 °C. Different levels of crystallinity and ordering degree were observed depending upon the chemical environment or the combination between divalent and trivalent cations. The results from high-resolution transmission electron microscopy revealed that nanostructured layered samples were obtained with interplanar spacing compatible with previous literature. Raman scattering was employed to investigate the complex band structure observed, particularly the lattice vibrations at lower frequencies, which is intimately correlated to the cationic radius of both divalent and trivalent ions. The results showed that strongly coordinated water and chloride ions besides highly structured hydroxide layers have a direct influence on the stability of the hydrotalcites. It was observed that transition and decomposition temperatures varied largely for different chemical compositions.     

Microwave assisted preparation of Fe doped β-dicalcium silicate by sol-gel method

Fe³⁺ doped and undoped β-dicalcium silicates (β-Ca₂SiO₄ or β-C₂S) were prepared by sol-gel method. The gels formed were heated in a microwave oven and subsequently in a muffle furnace. The particle sizes of doped and undoped samples were found to be about 150 nm and 600 nm respectively. The materials were characterized by scanning electron microscopic, powder X-ray diffraction, BET specific area measurements, infrared spectroscopic and Mössbauer spectroscopic techniques. IR spectroscopic studies showed the possibility of distorted tetrahedral symmetry in Fe³⁺ doped β-C₂S. Calorimetric studies have shown that iron doped β-C₂S is highly reactive. From Mössbauer spectroscopic studies it is found that electronic environment of Fe³⁺ in β-C₂S is changed due to hydration. Degree of hydration calculated from non-equilibrium water content measurements have shown that Fe³⁺ doped β-C₂S hydrates at a much higher rate. Scanning electron microscopic studies have revealed that the hydration products in both the cases are almost identical. Formation and hydration of β-C₂S in the presence of Fe³⁺ have been understood.     

A Facile Way for Synthesis of High Performance Electron Receptor MCB: A Promising Replacer of PCBM

Methyl 4-C₆₁-benzoate (MCB) series fullerene materials with low cost and high yield, including monoadduct (MCBM) and bisadduct (MCBB) compounds, were synthesized and their photophysical and electrochemical properties were investigated. Fabricated photovoltaic devices based on both two materials showed power conversion efficiency of 3.48% and 0.16%, respectively. The MCBM exhibited higher PCE relative to PCBM's 3.40%. The LUMO energy level of MCBM was 0.03 eV lower than that of PCBM, and it was facile to be synthesized by two steps with high yield of 55% from low-cost industrial commercials, whose molecular weight was 868.0 g/mol. This work supplied new route to design fullerene materials as PCBM's alternative.     

The effect of mechanical activation on the synthesis of biocompatible Ca10(PO4)6(OH)2

The effect of mechanical activation on the course of reactions involved in the synthesis of calcium hydroxyapatite Ca₁₀(PO₄)₆(OH)₂ was studied; the composition, crystallographic parameters, spectroscopic characteristics, and dielectric properties of the products were determined. The role of the composition of initial components on the rate of synthesis is analyzed.     

Improved Photo-Excited Carriers Transportation of WS2-O-Doped-Graphene Heterostructures for Solar Steam Generation (Small 19/2023)

Two-dimensional (2D) transition metal dichalcogenides and graphene have revealed promising applications in optoelectronic and energy storage and conversion. However, there are rare reports of modifying the light-to-heat transformation via preparing their heterostructures for solar steam generation. In this work, commercial WS₂ and sucrose are utilized as precursors to produce 2D WS₂-O-doped-graphene heterostructures (WS₂-O-graphene) for solar water evaporation. The WS₂-O-graphene evaporators demonstrate excellent average water evaporation rate (2.11 kg m⁻² h⁻¹) and energy efficiency (82.2%), which are 1.3- and 1.2-fold higher than WS₂ and O-doped graphene-based evaporators, respectively. Furthermore, for the real seawater with different pH values (pH 1 and 12) and rhodamine B pollutants, the WS₂-O-graphene evaporators show great average evaporation rates (≈2.08 and 2.09 kg m⁻² h⁻¹, respectively) for producing freshwater with an extremely low-grade of dye residual and nearly neutral pH values. More interestingly, due to the self-storage water ability of WS₂-O-graphene evaporators, water evaporation can be implemented without the presence of bulk water. As a result, the evaporation rate reaches 3.23 kg m⁻² h⁻¹, which is ≈1.5 times higher than the regular solar water evaporation system. This work provides a new approach for preparing 2D transition metal dichalcogenides and graphene heterostructures for efficient solar water evaporation.