Transition Metal Chemistry最新文献

The article presents the results of flotation beneficiation experiments for polymetallic ore of complex mineralogical composition with the use of alkylbenzenesulfonic acid (ABSA) as a frothing reagent. Additional experiments showed the highest efficiency of ABSA application for samples of mixed-type ores, showing a significant increase in the recovery of gold, copper, zinc, and lead in the collective concentrates of flotation beneficiation. The use of an ABSA activator promotes the additional cleaning of fragments containing valuable metals from oxide films and coatings, as well as the transfer of microparticles of valuable metals due to the adsorption properties of organics and the formation of metal–carbon bonds. Another effect of this reagent use is an increase in the mass yield of concentrate while maintaining the quality parameters. Gold recovery in the main collective flotation concentrate more than doubled from 46.81 to 97.06%; copper recovery increased from 67.5 to 90.8%, zinc from 22.04 to 58.81%; and lead from 51.13 to 81.1% during the beneficiation process of polymetallic ore with the use of ABSA. A similar effect was observed for beneficiation of copper ore with complex composition; copper recovery in the main concentrate increased from 33.57 to 87.61%. Selective flotation with the development of gold concentrate from difficult-to-beneficiate polymetallic ore also showed a significant increase in gold recovery from 60.41 to 90.24% with ABSA pretreatment.

This study explores the synthesis, characterization, and optimization of zinc sulfide nanoparticles (ZnS-NPs) for the adsorption of Acid Green 25 (AG-25) dye from wastewater. ZnS-NPs were synthesized via the co-precipitation method and characterized by SEM, EDX, UV–Vis, FTIR, and XRD analyses, confirming a granular hierarchical structure, high purity showing a significant absorption peak at 310 nm and face-centered cubic crystal lattice with characteristic peaks matching with JCPDS file number 5-0566. The calculated band gap was 3.5 eV and the point of zero charge (PZC) was 5.84 indicating pH-dependent surface charge properties. Maximum adsorption was achieved using 0.3 g of ZnS-NPs adsorbent dose and 10 ppm of dye at pH 3 in 30 min; adsorption process followed the pseudo-first-order model (R² = 0.997) suggesting physisorption, while followed isotherm model was Temkin isotherm with R² = 0.8202 describing the adsorption equilibrium highlighting interactions between adsorbate molecules. Response Surface Methodology (RSM) optimization was used with Central Composite Design (CCD) to evaluate four factors such as pH, adsorbent dose, dye concentration and contact time to maximize adsorption efficiency. ANOVA analysis revealed a highly significant quadratic model (p < 0.0001) with optimal conditions for dye removal and validated experimentally with a negligible error of 1.2% compared to predicted values. The RSM model demonstrated high predictive accuracy with R² = 0.9784 and an insignificant lack of fit (p = 0.1337) underscoring ZnS-NPs as a robust, cost-effective and environmentally friendly adsorbent for industrial wastewater treatment.

A novel γ-Al₂O₃/IL-Pd catalyst was designed and synthesized; this catalyst features highly dispersed deposition of active palladium nanoparticles on the surface of porous γ-Al₂O₃, and its catalytic performance and recyclability are improved. The incorporation of ionic liquids is critical to catalyst design since it facilitates the complete dispersion of active metals through chelation; this effectively prevents the formation of palladium black and addresses catalyst deactivation. The interaction between the ionic liquid and the support likely occurs through specific coordination reactions; this interaction significantly enhances the recovery and reusability of the catalyst by preventing the leaching and sintering of the palladium nanoparticles. This approach not only resolves the agglomeration issue inherent to γ-Al₂O₃, but also further optimizes the catalyst performance. In the Suzuki‒Miyaura coupling reaction, the new catalyst demonstrates remarkable catalytic activity and achieves a tetramethoxybiphenyl yield of up to 99% within a remarkably short reaction time of just 30 min, without the need for inert gas protection. Notably, after ten consecutive cycles, the catalyst’s performance remains at 94%, outperforming many existing catalysts and confirming its exceptional stability and recyclability. Given its high efficiency, stability, and reusability, this catalyst can likely serve as a high-performance multifunctional catalytic platform for a range of significant organic synthesis reactions.

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Electrochromism is the process of changing a material’s optical glaze from coloured to bleached and vice versa by applying a reversible voltage. It is worth noting that across all transition metal oxides, tungsten oxide (WO₃) has acquired a prime focus owing to its versatile electrochromic properties. High coloration efficiency, high diffusion coefficient (D), high cyclic stability, high optical modulation, and fast switching time are few properties which makes WO₃, a versatile electrochromic material. Over the years, many scientists and researchers have been encouraged to extravagant their work on WO₃, to realise its hidden electrochromic persona. Various nanostructured forms of WO₃ have been studied till now. Every form of WO₃ film defines a different electrochromic capability. In this review we try to portray versatility of various nanostructured forms of WO₃ such as nanowires, nanorods, nanotrees, nanoflowers, nanoflakes, and nanoporous films towards acquiring electrochromic state of the art.

Proton-coupled electron transfer (PCET) is a common reaction in biological systems, with potential implications for DNA damage and repair. This study showed that tris-(2-pyridine carboxylate) chromium (III) (complex 1) exhibited an increased electrochemical reaction rate in the presence of a strong acid, suggesting that PCET via proton donation promotes the reduction reaction. Conversely, complex 1 with picolinic acid showed a decreased electrochemical exchange constant, suggesting kinetic control by slow electronic exchange, consistent with PCET. Bis(pyridine-2,6-dicarboxylate) chromate (III) of sodium (complex 2), showed potential shifts and broadening of signals in the presence of dipicolinic and ascorbic acids, further supporting the involvement of PCET. Overall, the study highlighted the modulation of the electrochemical behavior of the chromium complexes through proton-coupled shifts in reduction potentials and kinetics, shedding light on their potential interactions with cellular reductant agents and protons. The weaker interactions of complexes 1 and 2 with BSA and DNA, together with their lower bioavailability and solubility compared to CQDP, contribute to our understanding of the potential biological effects of the chromium complexes studied. This abstract provides a comprehensive overview of the results of the study, highlighting the significance of the PCET reactions and their potential implications for biological processes and health effects.

The Successive Ionic Layer Adsorption and Reaction (SILAR) technique is a versatile method for depositing thin films with controlled thickness surfaces. However, achieving high-quality thin films with an optimal number of deposition cycles required to improve film properties applicable in photocatalysis is an important consideration. In this study, we investigate the influence of the number of cycles (3, 6, 9, 12, and 15 cycles) in the SILAR technique on the characteristic parameters, including the structural, morphological, and optical properties of deposited Ba/ZnO thin films on glass substrates. X-ray diffraction analysis reveals the hexagonal polycrystalline nature of Ba-doped ZnO films. The intensity of peaks increased with increasing of cycles number which the preferred orientation was (002), while the crystallite size decreasing from 11.105 to 10.904 nm. SEM shows grain size increasing from 29.71 to 44.79 nm as SILAR growth cycles rise from 3 to 15. The thin films' transmittance measurements ranged from 290 to 1200 nm. The thin films' energy band gaps decreased from 3.68 to 3.25. Additionally, the wettability of Ba-doped ZnO films increased with the number of SILAR cycles, rising from 21.23° at 3 cycles to 56.55° at 15 cycles. Furthermore, the photocatalytic performance of samples under visible sunlight was studied for methylene blue and amoxicillin at different cycle numbers. At 15 cycles, the degradation of methylene blue reached 93.51%, whereas amoxicillin was degraded by 54.31%. This study offers valuable insights into the influence of Ba-doped ZnO thin films with varying cycles on the quality of thin films, which is an applicable facility in photocatalytic degradation.

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In this work, we discuss the effect of annealing temperature on the structural, morphological optical and photocatalytic properties of zinc oxide (ZnO) thin films prepared by using dip-coating technique on porous ceramic substrates at different annealing temperatures of 400 °C, 500 °C, 600 °C, and 700 °C for 2 h. The photocatalytic activity of the prepared ZnO photocatalysts was examined by evaluating the degradation of Orange II (OII) as a model of dyes under light irradiation. ZnO photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–visible absorption spectroscopy. SEM analysis revealed that the annealing temperatures greatly affected the grain size and the topography of ZnO surfaces. XRD results showed that all samples have a polycrystalline nature with a hexagonal wurtzite structure. The experimental data demonstrated that the average crystallite size of the prepared ZnO thin films varied from 15 to 24 nm with the increase of the annealing temperatures from 400 °C to 700 °C. The UV–Vis data indicated an enhancement in the absorbance of ZnO thin films across the ultraviolet range with increased annealing temperatures. The photodegradation rate increased to 94.7% by increasing the annealing temperatures.

Nanotechnology plays a crucial role in advancing medical research, particularly in developing effective therapeutic agents. However, challenges such as nanoparticle agglomeration and limited functionalization persist in optimizing their biological applications. This study addresses these issues by synthesizing copper oxide nanoparticles (CuO NPs) using a combustion method with aqueous Acacia nilotica gum as biofuel, and creating silver-doped CuO nanocomposites (Ag/CuO NCs) with varying silver compositions. Notably, silver doping significantly enhanced crystallinity and reduced agglomeration, resulting in average crystallite sizes ranging from 10 to 25 nm. Characterization techniques, including X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy, and ultraviolet–visible spectroscopy. Both CuO and Ag/CuO NCs exhibited strong antimycobacterial properties. Antioxidant activity was assessed through DPPH testing, demonstrating improved IC50 values as silver concentration increased (e.g., 2.40 mg/mL for Ag/CuO with 9 mol %Ag). Further, cytotoxicity tests using the HT-29 human colon cancer cell line revealed an IC50 of 4.932 µg/mL for Ag/CuO (9 mol %Ag), with anticancer activity evaluated across concentrations of 0.75–40 µg/mL. Importantly, toxicological evaluations indicated compatibility of both CuO NPs and Ag/CuO NCs with human red blood cells, underscoring their potential for biomedical applications. This work presents a novel approach to enhancing the functionalization of metal oxide nanoparticles, paving the way for future therapeutic advancements.

Low-crystallinity and ultrathin iron phosphide nanosheets loading on carbon paper (FeP sheets/CP) were synthesized by hydrothermal and solid–gas phosphating method, acting as an efficient self-supporting electrode for hydrogen evolution reaction (HER). Compared with FeP cubes/CP and FeP rods/CP composites, FeP sheets/CP composites exhibit higher specific surface area due to its lamellar structure favoring the exposure of active sites. Meanwhile, the FeP sheet exhibits low crystallinity due to the addition of surfactant and low-boiling-point ethanol solvent. Electrochemical measurements showed that FeP sheets/CP composites showed great electrocatalytic activity against HER, with overpotentials of only 73 and 156 mV at current density of 10 mA cm⁻² in 0.5 M H₂SO₄ and 1.0 M KOH, respectively.

The development of polyoxometalate-based hybrid compounds offered a hopeful opportunity to develop capacitor electrode materials. Herein, two new polyoxometalate-based hybrid compounds, [Cu(4 − INCN)₂(ε − Mo₈O₂₆)_0.5] (1) and [Zn(H₂O)(4 − INCN)₃(β − Mo₈O₂₆)_0.5], were synthesized under hydrothermal condition by using 4 − imidazol − 1 − yl − naphthalene − 1 − carbonitrile (4 − INCN) as N-donor ligand. The [ε − Mo₈O₂₆]⁴⁻ and [β − Mo₈O₂₆]⁴⁻ anions were involved in the structures of two compounds, respectively. Compound 1 displayed a two-dimensional layer structure, where the [ε − Mo₈O₂₆]⁴⁻ anions were gathered by Cu (II) ions to produce a two-dimensional structure with the 4 − INCN as monodentate organic ligands hanged on the both sides. In the structure of compound 2, the aggregation of [β − Mo₈O₂₆]⁴⁻ and Zn (II) ions resulted in a one-dimensional chain, which was decorated by the 4-INCN ligands through coordination with Zn (II) ions. Two compounds as electrode materials provided specific capacitances of 1092 F g^–1 for 1 and 731 F g^–1 for 2 at the current densities of 1 A g^–1, and showed excellent capacitance retention rates after 1000 cycles. These findings provided a possible approach in the preparation of POM-based hybrid compounds employed as capacitor electrode materials.