Transition Metal Chemistry最新文献

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.

Researchers are increasingly studying and practicing advanced oxidation processes (AOPs) for micropollutant abatement in drinking water treatment and potable water reuse. This study conducted the comparison of the UV/chlorine, Fe (II)/UV/Chlorine, and Cu (II)/UV/Chlorine processes for the degradation of Ponceau S azo dye aqueous solution. The experimental study shows an enhancement in the degradation rate of PS dye in which complete degradation was obtained at 10 min reaction time when Fe²⁺ and Cu²⁺ were added to the solution. This improvement is due to catalyzing HOCl by ferrous and copper ions.

Using the density functional theory (DFT) with the hybrid method B3LYP by 6–311 + G(d,p) basis set, all theoretical calculations and optimum geometric parameters have been computed. We are able to identify Ponceau's electronic and energetic actions thanks to this investigation. Natural population analysis (NPA) and the Mulliken population method have both been researched. The parr function has been used to study the molecule's ({P}_{k}^{-}) and ({P}_{k}^{+}) local reactivity. To visualize the charge transfer between the lone pairs and localized bonds, natural bond orbital (NBO) analysis is performed. DFT is also used to examine molecular electrostatic potential (MEP) and to describe orbital hybridization. The study's findings suggest that both processes are viable for dye removal in water treatment, though further optimization of operating conditions, such as pH and metal ion concentration, could further improve performance.

The scientific community has long been intrigued by the potential practical applications of metal nanoparticles. In this research, we developed cost-effective and easily accessible palladium nanoparticle (Pd-NP)-supported biocatalysts using natural materials. Our main challenge was to ensure an even distribution of Pd-NPs on the bacterial surface while preventing their detachment during the reaction. We successfully addressed this challenge by employing a suitable synthesis method and covering the Pd-NP-coated bacteria with sericin. In our approach, we synthesized Pd-NPs using an in-situ method. In brief, we adsorbed Pd(II) ions onto the bacterial surface and then reduced them using sodium borohydride. Subsequently, we used a sericin solution to enhance the catalytic system’s resistance to leaching and mechanical forces (such as shaking and drying). We thoroughly characterized the morphology and structure of the heterogeneous biocatalysts prepared using FTIR, TGA, EDX, SEM, XRD, and TEM techniques. The catalytic efficiency of the bacteria-Pd-sericin nano-biocomposite was evaluated in the Heck coupling reaction. Our biocatalyst demonstrated high catalytic activity, rapid reaction times, and exceptional reusability, remaining active for up to four successive reaction cycles.

Nitroaromatic compounds are common toxic matters discharged as wastewater in varied industries. Reducing them into corresponding aromatic amines can not only decrease their contamination but also obtain value-added products, in which the preparation of catalysts with superior properties is the key. Herein, the spherical Cu-Ag architectures (ATs) are constructed via a two-step wet chemical method. First, the Cu microspheres are fabricated with the assistance of polyvinylpyrrolidone (PVP) in the mixed solution of ethylene glycol (EG) and water. Then, using them as templates, the spherical Cu-Ag ATs can be grown and constructed. The as-obtained Cu-Ag ATs have the spherical outlines assembled by many nanoparticles. The sliced Cu-Ag ATs show hollow structures and many nanothorns grow from the center to the around, combining the roughly spherical shell to build up the Cu-Ag ATs. In the reduction reaction of p-nitrophenol and p-nitroaniline, the spherical Cu-Ag ATs all exhibit excellent catalytic activities. Within 85 s and 80 s, the p-nitrophenol and p-nitroaniline can be converted completely. The prepared Cu-Ag ATs are expected to have potentials in other fields, such as electronics, sensors and so on.

Graphical abstract

The hierarchical Cu-Ag architectures are constructed successfully through a two-step wet chemical method, in which the rough Cu microspheres are first fabricated in aqueous EG solution, and are used as templates to direct the growth of Cu-Ag architectures. In both reduction of p-nitrophenol and p-nitroaniline, the Cu-Ag architectures exhibit high catalytic activities.

Sheet-like ZnO nanoparticles (SZNs) were synthesized using a microemulsion method and characterized by XRD, BET, DRS, and FESEM techniques. These nanoparticles were then utilized as selective ethanol sensors operating at temperatures between 300 and 450 °C. When precursor ZnO concentrations were high, the average particle size of the SZNs increased, which was reflected in the sharper diffraction peaks observed in the XRD results. The low band gap of SZNs, attributed to their 2D morphology, was confirmed by the Tauc diagram. The SZN sensors demonstrated a remarkable selectivity for ethanol, with response levels up to 77 times higher than for CO and 3700 times higher than for CH₄, achieving a limit of detection between 2.7 and 13.3 ppm. By fine-tuning the microemulsion conditions, the SZN4 sensor achieved an exceptionally high response to ethanol, about 106 times, and up to 30 times higher compared to TCE, toluene, and propane. Furthermore, the SZN4 and SZN5 sensors exhibited a relative insensitivity to humidity, with only a 26% and 17% reduction in ethanol response, respectively.

Graphical abstract

Ni extraction from laterite ore has progressively intensified via various hydrometallurgical methods. One of the by-products of the leaching process is Mn, which can increase the resilience of this metal supply on the market. By observing the effects of the laterite roasting temperature and the effects of the Mn leaching temperature and duration, we can obtain insight into the coextraction of Mn from laterite leaching. Roasting was carried out at 280 and 610 °C, whereas leaching experiments were conducted at 30–90 °C for 0–120 min. The leaching efficiency of Mn increased with increasing roasting temperature, leaching temperature, and leaching duration. The optimum leaching conditions were obtained using a 280 °C roasted sample at a leaching temperature of 90 °C for 90 min. Under these conditions, the Mn leaching efficiency reached 95.5%. Roasting also affects the Mn leaching kinetics parameters, and increasing the roasting temperature results in an increase in the Ea value of the leaching process.

This research study shows that naturally occurring goethite-rich iron ore from the Tebessa region of Algeria can be positioned as a sustainable and cost-effective alternative for water treatment and natural catalyst development. This locally sourced and naturally occurring iron ore promotes a heterogeneous Fenton-like reaction for the decolorization of brilliant green (BG) dye under neutral pH conditions. The iron ore sample was collected and processed using cost-effective laboratory preparation methods. The treated iron ore sample has been thoroughly characterized in terms of composition, structure, and morphology revealing that the natural iron ore consists mainly of goethite (59%), with minor amounts of quartz, illite, and kaolinite. Further analysis showed that the studied ore exhibits mesoporous properties with a BET-surface area of 45 m²/g. UV–Vis diffuse reflectance spectroscopy confirmed the presence of iron oxide minerals, notably goethite and hematite phases. Indeed, we investigated the decolorization rate of BG dye solution using different concentrations of H₂O₂ activated with different doses of goethite-rich iron ore catalyst at 25 °C and 45 °C. During this heterogenous process, several kinetic models were examined. Preliminary experiments revealed that the optimal conditions for achieving 95% BG dye decolorization were a dye concentration of 10 mg/L, an H₂O₂ concentration of 3.0 mM, and an iron ore catalyst dose of 0.2 g/L, all within a reaction time of 2 h. This work may contribute to advance the use of natural catalysts in the challenging task of decolorization of other dyes.

Three new mononuclear Zn^II and Cd^II complexes have been designed and synthesized by using 2-phenoxyaniline Schiff base as ligands. Complexes 1–3 have been characterized by elemental analysis, FT-IR, ¹H NMR, and single-crystal X-ray diffraction. The structures of complexes 1–3 were analyzed by single-crystal X-ray diffraction, and intermolecular hydrogen bonds (C–H···Cl and π···π stacking) were found to connect the mononuclear molecules, forming supramolecular structures. The relationships between their photophysical properties and structures were studied by UV–visible absorption spectroscopy and fluorescence spectroscopy. The maximum emission wavelengths of complexes 1–3 in solid state vary within the range of 494–533 nm, and they emit bright yellow-green fluorescence under UV lamp irradiation. These properties indicate that these complexes can be used as potential fluorescent materials. Also, the molecular orbital densities and different energy levels are obtained by using the density functional theory methods.

Three metal organic frameworks [Cu₃(tpyc)₃(H₂btc)(Hbtc)·5H₂O]_n (1) [Mn(tpyc)(H₂O)₂·ClO₄]_n (2) and [Mn(tpyc)(bdc)_0.5(H₂O)]_n (3) have been synthesized by using 2,2′:6′2′′-terpyridine-4′-carboxylic acid (Htpyc) in the presence of different auxiliary ligands (H₃btc = 1,3,5-benzenetricarboxylic acid, H₂suc = succinic acid, H₂bdc = 1,4-benzene dicarboxylic acid) under solvothermal conditions. They were analyzed by elemental analysis, FT-IR, X-ray single crystal diffraction, PXRD and TGA. The results show that MOF 1 displays a 1D chain structure, which is further assembled to a 3D architecture via multiple intermolecular hydrogen bonds. MOF 2 also presents a 1D chain structure and the adjacent chains are further connected by hydrogen bonds O1–H1B∙∙∙O2#1, finally forming a 2D layered structure. For MOF 3, its 3D framework structure is formed by hydrogen bond O5–H5A∙∙∙O2#1 and O5–H5B∙∙∙O3#2 interaction between adjacent 1D chains. Furthermore, dye adsorption studies indicate that MOF 3 can selectively adsorb organic dye Congo red.

Due to the potential applications of bioactive compounds, two isomorphous mononuclear coordination polymers [M(pydc)(H₂O)]_n (M = Cd (1), Mn (2), H₂pydc = 5-hydroxypyrazine-2-carboxylic acid) were synthesized and fully characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, infrared spectroscopy, ¹H nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy and powder X-ray diffraction analysis. Complexes 1 and 2 are six-coordinated motifs and exhibit slightly deformed octahedral geometry, which extends into three-dimensional frame structures. Complexes 1 and 2 interact with calf thymus DNA (CT-DNA) through intercalation, hydrogen bonding and van der Waals forces. Both complexes had good binding propensity for bovine serum albumin (BSA) with a relatively high binding constant (10⁴ L mol⁻¹) superior to that of H₂pydc (10³ L mol⁻¹). The interactions between H₂pydc, complexes 1 and 2 and BSA were static quenching procedures. Site competition experiments showed that the ligands and complexes interact with BSA at site II.