Transition Metal Chemistry最新文献

This study reports the synthesis and thorough characterization of two semi-organic crystals, (C₅H₇N₂)₂[ZnX₄] (X = Cl, Br), grown by the slow evaporation solution technique. Single-crystal X-ray diffraction revealed that compound (1) crystallizes in the tetragonal system (I4̅2d) and compound (2) in the orthorhombic system (P2₁2₁2₁), both non-centrosymmetric. Hirshfeld surface analysis and fingerprint plots highlighted strong N–H…X hydrogen bonds between the organic cations and [ZnX₄] anions, enhancing structural stability. Phase purity was confirmed by powder X-ray diffraction, while Fourier-transform infrared spectroscopy validated the presence of key functional groups. UV–Vis absorption spectra showed prominent bands at 253 nm and 262 nm, attributed to π–π* transitions, with optical bandgap energies estimated using Tauc plots. Second harmonic generation measurements under P₂ω excitation exhibited intense green emission at 532 nm, confirming the materials nonlinear optical activity. Continuous symmetry measure analysis indicated near-ideal tetrahedral geometry of the [ZnX₄] anions. Thermal stability was assessed by thermogravimetric analysis, and scanning electron microscopy revealed irregular, micron-scale particles with irregular surfaces. Energy-dispersive X-ray spectroscopy verified the elemental composition, confirming zinc and halide incorporation. Overall, these results provide valuable insights into the structural, optical, and thermal properties, underscoring the potential of these materials for nonlinear optical applications and antibacterial activity.‏‏

Mn²⁺-, Ni²⁺-, and Co³⁺-doped pyrrhotite nanoparticles were synthesized via the hot injection thermolysis method. The optical and structural properties of the pure and doped pyrrhotite nanoparticles were studied using UV–visible spectroscopy. Powder X-ray diffractometry (p-XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were used to characterize the particles. p-XRD studies showed that doping had no effect on the basic structure of the nanoparticles. The doped nanoparticles showed the formation of single-phase monoclinic type pyrrhotite (Fe_1-xS) structure. UV–visible spectroscopy revealed that the incorporation of Ni²⁺, Fe³⁺, and Co³⁺ ions as dopants decreases the energy bandgap of the pyrrhotite nanoparticles. TEM images showed an increase in nanoparticle sizes with the incorporation of dopants. Both elemental mapping and EDX analysis of the doped nanoparticles reveal the presence of Mn²⁺, Ni²⁺, and Co³⁺ doping ions in the pyrrhotite lattice.

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Using a one-step co-reduction method, AgCu bimetallic nanoparticles have been successfully loaded onto few-layer boron nitride nanosheets (BNNSs), which possess high thermal conductivity. The structure and morphology of both the support and the catalyst were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). Furthermore, the influence of near-infrared laser irradiation on the catalytic performance of the catalyst was investigated. The study found that the Ag₁Cu₁/BNNSs nanocomposite exhibited significant catalytic activity in the reduction of 4-nitrophenol (4-NP). This nanocomposite had an activation energy of only 42.9 kJ/mol and maintained high catalytic activity even after six cycles. Additionally, it was found that near-infrared laser irradiation further enhanced the catalytic activity of the composite material. This enhancement was primarily attributed to the photothermal effect of Ag nanoparticles. Moreover, the BNNSs possess high thermal conductivity. They transferred the photothermal energy generated by the Ag nanoparticles to the external environment, thereby further enhancing the local thermal effect of the catalyst. This work provided a foundation for advancing near-infrared or solar photothermal-enhanced bimetallic nanocomposite catalytic systems.

Pyrochemical reprocessing has emerged as a crucial alternative to conventional hydrometallurgical methods for the reprocessing of spent nuclear fuel (SNF), particularly for high-burnup SNF from advanced reactors. Unlike the Plutonium Uranium Recovery by Extraction (PUREX) process, which encounters challenges with high-burnup SNF, pyrochemical reprocessing facilitates the direct processing of short-cooled fuel through electroreduction and electrorefining in molten salt. This review presents the research advancements in electroreduction and electrorefining within the context of pyrochemical reprocessing of SNF, systematically introducing the latest findings across five key areas: the electroreduction of oxide SNF pellets composed of various materials, anode materials, solid cathode materials, liquid cathode materials, and molten salt systems utilized in the electroreduction and electrorefining processes. Finally, the article summarizes the pressing issues currently facing electroreduction and electrorefining and proposes directions for future research.

The mechanism of carbon dioxide (CO₂) activation by the electrochemical reduction of molybdenum hexacarbonyl (Mo(CO)₆) in dry organic solvent was reinvestigated using IR spectroelectrochemistry (IR-SEC) combined with density functional theory (DFT) calculations. Cyclic voltammetry (CV) and IR-SEC experiments, carried out under inert atmosphere, confirmed that the stable pentacarbonyl dianion [Mo(CO)₅]²⁻ is readily formed at the reduction potential of the hexacarbonyl parent complex. In addition, IR-SEC monitoring of the reduction of Mo(CO)₆ in CO₂-saturated solution showed an absorption band ascribed to the formation of bicarbonate (HCO₃⁻), but no signs for the formation of formate (HCO₂⁻) or oxalate (C₂O₄²⁻). These experimental results were rationalized by DFT calculations on the coordination mode of CO₂ to [Mo(CO)₅]²⁻. Indeed, no stable structure could be calculated for the η¹-OCO isomer, whereas the optimized structure of the η²-CO₂ isomer was calculated to be energetically less stable than that of the η¹-CO₂ isomer, the latter being identified as a key intermediate for the selective formation of carbon monoxide (CO) and water (H₂O) upon O-protonation of the CO₂-adduct. This catalytic behavior is discussed here in terms of Mulliken atomic charge redistribution over the CO₂ binding and activation processes, and compared with what was previously reported for tetracarbonyl Mo-diimine complexes, where diimine ligands display “redox non-innocent” properties.

A sustainable solution to the intermittent nature of solar energy is using photocatalysts powered by sunlight to produce hydrogen from water, which offers a green substitute for fossil fuels. As the most promising semiconductor material for photocatalytic water splitting, TiO₂-based nanomaterials have received increasing attention from researchers in academia and industry in recent years. However, challenges remain to be addressed, such as a large bandgap, electron–hole recombination, preparation imperfections, and the possibility of excessive H2 production. Several approaches, including the addition of electron donors, doping, and defect engineering have been studied to overcome these constraints and enhance TiO₂ performance. Here, we provide a concise overview of the various techniques used to synthesize TiO₂-nanostructured photocatalyst. The present study also provides an overview of recent studies on the various factors influencing the photocatalytic process that produces H2 through water splitting. Important properties of photocatalysts include surface chemistry, particle size, pH, temperature, light source, electron donors, band gap, and the synthesis of both pure and doped TiO₂ photocatalyst materials are also discussed. Additionally, a comparative hydrogen generation rate is tabulated to get insight into the most effective synthesis process and type of TiO₂ for effective photocatalysis.

Graphical abstract

A new coordination compound of Ni(II) with nicotinamide (Nic) and 1,5-naphthalenedisulfonic acid (H₂NDS) of formula {[Ni(Nic)₂(H₂O)₄]NDS}.3H₂O (NNDSN) has been prepared by gel diffusion technique. SXRD data show that the compound crystallizes in triclinic space group P (overline{1 }). In the crystal structure, the Ni(II) ion is coordinated with two nicotinamide units through the nitrogen atom of pyridine ring and four water molecules. The distorted octahedral geometry of the six coordinate Ni(II) compound can be understood from the (angle) N–Ni–O (ranges from 86.59(7) to 93.41(7)°), (angle) O–Ni–O (88.63(7)° and 91.37(7)°) and difference in bond distances of Ni–O (2.0505(15) and 2.0533(16) Å) and Ni–N (2.1323(17) Å). 1,5-Naphthalenedisulfonate ions present in the crystal lattice balance the charge of Ni(II) ions. In the crystal structure, both coordinated and lattice water molecules, sulfonate groups of 1,5-naphthalenedisulfonate ions and NH₂ group of nicotinamide molecules are involved in intermolecular hydrogen bonding. These interactions further stabilize the crystal structure. FT-IR spectral studies show that SO₃⁻ group of 1,5-naphthalenedisulfonate ion, C = O and NH₂ groups of nicotinamide molecule are not involved in coordinate bond formation. In the UV–vis spectrum, the peaks corresponding to ³A_2g → ³T_1g (P) and ³A_2g → ³T_1g (F) transitions are observed at λ_max of 388 and 685 nm respectively. TG/DTG studies show that the crystal structure is stable up to 102 °C and the decomposition to NiO takes place through six stages. Photoluminescence studies show that the emission intensity of NNDSN can be quenched by Fe³⁺ ions. This method can be used for the sensing of Fe³⁺ ion at micro level concentration.

Transition metal dichalcogenides (M = Mo, W, Re) have gained significant attention for electrocatalytic applications in renewable energy due to their unique layered structures. However, their catalytic activity is often limited by the inert nature of basal planes, with active sites primarily located along the edges. In this study, we employed doping as a strategy to enhance the catalytic performance of Re_(1−x)W_xS₂ alloys by increasing the density of active sites. Using Re₂(µ-S)₂(S₂CNEt₂)₄ (1) and WS₃(S₂CNEt₂)₂ (2) as precursors, thin films were synthesized via aerosol-assisted chemical vapor deposition at 500 °C. Comprehensive characterization using powder X-ray diffraction, Raman spectroscopy, inductively coupled plasma optical emission spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy (TEM) confirmed the successful formation of Re_(1−x)W_xS₂ alloys. TEM analysis revealed a phase transition from 1T to 2H at W concentrations between 22.6 and 30.8%, indicating a structural evolution from the ReS₂ (1T) to WS₂ (2H) phase. Catalytic testing of both bulk and exfoliated materials in hydrogen evolution demonstrated that doping-induced structural modifications led to a higher density of catalytically active sites, significantly enhancing performance. These findings underscore the role of doping in tailoring the electronic and structural properties of TMDCs to optimize their catalytic efficiency, paving the way for their broader application in sustainable energy technologies.

The removal of organic pollutants, particularly textile dyes, using green and efficient methods is a key focus for researchers addressing environmental pollution. Advanced oxidation processes (AOPs), especially the Fenton-like process, have garnered significant attention for their ability to break down recalcitrant organic molecules into harmless byproducts, namely water and carbon dioxide, through the generation of hydroxyl radicals (^·OH). In this study, a heterogeneous Fenton-like catalyst, copper phosphate Cu₃(PO₄)₂, was synthesized in the presence of oxalate to achieve a unique morphology. The material was characterized by various physicochemical techniques, including TG, XRD, SEM, UV–Vis, XPS, photoluminescence (PL), and electrochemical impedance spectroscopy (EIS), to evaluate its potential for degrading Basic Yellow 28 (BY-28), a common organic dye of the textile industry. The degradation process was conducted at neutral pH with a BY-28 dye concentration of 20 mg L⁻¹ and a catalyst dose of 1 g L⁻¹. The catalytic activity is attributed to the high concentration of Cu²⁺ on the catalyst surface, which efficiently generates ^•OH radicals by activating hydrogen peroxide (H₂O₂).

Under hydrothermal conditions, a two-dimensional (2D) Anderson-type polyoxometalate-based framework {[Cu(dap)₂][Cu(dap)(H₂O)₂]₂[TeMo₆O₂₄]} (1, dap = 1,2-diaminopropane) was synthesized and characterized by single crystal X-ray diffraction analysis, elemental analysis, IR spectroscopy, electrochemical impedance spectroscopy and powder X-ray diffraction. Complex 1 features an unusual mixed-linkage 2D metal–organic network constructed from both single [Cu(dap)₂]²⁺ and double [Cu(dap)(H₂O)₂]²⁺ linkers. As a heterogeneous catalyst, 1 exhibited outstanding catalytic performance for the oxidation of 2-chloroethyl ethyl sulfide, achieving 99.1% conversion and 100% selectivity toward CEESO within 10 min at 35 °C, accompanied by excellent structural and catalytic stability. Moreover, 1 demonstrated promising electrochemical sensing properties of Cu²⁺ ions, showing a low limit of detection of 0.492 μM, a high sensitivity of 0.426 μA μM⁻¹ and good anti-interference ability.