Research on Chemical Intermediates最新文献

This study constructed an electrocatalyst of ultrafine platinum nanoparticles (UPt NPs) loaded onto nitrogen-rich porous hollow carbon spheres (NC). Using ZnO as a sacrificial template, NC carriers with a high specific surface area (516.4 m²/g) and hierarchical pore structure were prepared via ZIF-8 coating and carbonization. Pyridine/pyrrole nitrogen doping significantly enhanced the strong mutual interaction (SMSI) between Pt and the carrier. Combined with a mild photo-induced approach, the hydrolysis pathway of the Pt precursor was controlled by adjusting the light wavelength (UV/blue-violet/green light), enabling in situ reduction of Pt on the NC surface and within its pore network at room temperature while effectively suppressing agglomeration. Electrochemical testing revealed that the NC/Pt-UV2 catalyst, synthesized using 2 mM Pt precursor combined with UV light, exhibited a mass-specific activity (1179.5 mA·mg_Pt⁻¹) and electrochemically active area (135.8 m² g⁻¹) 4.96 and 5.17 times higher than commercial Pt/C, respectively, with superior activity retention compared to Pt/C after 3600 s of constant-potential testing. This work proposes a method for preparing nitrogen-rich hollow carbon spheres with high specific surface area and a novel strategy for the green, efficient synthesis of ultrafine Pt nanoparticles, offering new insights for the design of supported electrocatalysts.

With the advancement of globalization and the continuous growth of the global population, issues related to water resource scarcity and water pollution have become increasingly severe. Antibiotics, as a significant class of environmental pollutants, are extensively used in human medicine and animal husbandry. Consequently, substantial amounts of antibiotics are discharged into the environment, adversely affecting human health and ecosystems. Among these antibiotics, tetracycline (TC) ranks second in both usage and production volume. This study investigates the degradation of tetracycline using FeOCl-activated persulfate, examining the effects of various systems, PMS concentration, TC concentration, FeOCl dosage, initial pH value, and the presence of anions and inorganic substances on TC degradation efficiency. Response surface methodology was employed to analyze the combined influence of PMS concentration, FeOCl dosage, and initial pH on TC degradation. Under the optimized conditions (PMS concentration = 1 mM, FeOCl dosage = 0.286 g/L, and initial pH = 8), the predicted maximum TC degradation efficiency of the system reached 93.45%. Quenching experiments were conducted using i-PrOH, benzoquinone, methanol, and tert-butanol to investigate the primary active substances involved in the degradation of TC. The degradation pathway of TC treated with the FeOCl/PMS system was inferred through mass spectrometry analysis.

The introduction of oxygen vacancies on the surface of catalysts is an important way to improve the performance of catalysis for oxidative desulfurization. In this study, Ni-doped CoMoO₄ catalysts with a significant number of oxygen vacancies were synthesized using hydrothermal methods. The structure of the catalysts was characterized through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N₂ adsorption–desorption techniques, and UV–visible diffuse reflectance (UV–Vis DRS). Compared to CoMoO₄, the specific surface area of Ni-CoMoO₄ decreased, but the performance of catalysis is improved due to the increased number of oxygen vacancies. The oxidative desulfurization experiments showed that catalytic activity was significantly enhanced by Ni doping. The optimum reaction conditions were determined to be a Ni/Co molar ratio of 1:20, a reaction temperature of 110 °C, a catalyst dose of 0.05 g, and an oxygen flow rate of 150 mL/min. The desulfurization rate of dibenzothiophene (DBT) in model oil could be as high as 96% under the optimum reaction conditions. The desulfurization mechanism of the catalyst was investigated by free radical-trapped experiments. This study proposes a novel strategy for oxidative desulfurization using metal-doped compounds with abundant oxygen vacancies as catalysts.

Graphical abstract

An inorganic material Ni-CoMoO₄ with a number of oxygen vacancies was synthesized by hydrothermal method and applied for removal of sulfur-containing compounds. It is necessary for ecological and environmental demands. This work provides a new idea for oxidative desulfurization using metal-doping compound containing a number of oxygen vacancies as catalysts.

Developing catalysts that combine high efficiency with recyclability is key to achieving sustainable organic synthesis. To this end, a novel [AcIm-Va]Br@Py-Imine-Cr@MCS complex was synthesized using the amino acid valine and subsequently immobilized on magnetic cellulose, forming a heterogeneous catalytic system. Physicochemical characterization of the catalyst was conducted using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The resulting ionic liquid-based catalyst demonstrated outstanding selectivity toward epoxide formation and achieved a remarkable catalytic efficiency of 98% in the epoxidation of diverse aromatic and aliphatic olefins. Maximum catalytic efficiency was achieved under mild and sustainable conditions, 50 ℃ with only 0.16 mol% Cr and 1.5 mmol H₂O₂, employing water as an eco-friendly solvent and hydrogen peroxide as a clean oxidant. The system's significant environmental and practical advantages arise from its heterogeneous nature, straightforward magnetic separation, excellent reusability, operation under mild conditions without high temperatures or additives, and minimal catalyst loading requirements, establishing it as a highly effective and sustainable epoxidation methodology. This strategy presents a sustainable and highly efficient route for olefin epoxidation.

In this paper, direct Z-type BiPO₄/Bi₂WO₆ heterojunctions were successfully prepared by a two-step solvothermal method using bismuth nitrate, disodium hydrogen phosphate, and sodium tungstate as precursors. The photocatalytic degradation capabilities of the composites for the antibiotic ciprofloxacin (CIP) were examined in circumstances that mimicked sunlight. The composites all showed high adsorption-catalytic properties compared with the monomer materials. Among them, 10 wt% BiPO₄/Bi₂WO₆ showed the highest degradation rate of 94.51% for CIP (20 mg/L) in 2 h. The composites were also found to be suitable for the photocatalytic degradation of ciprofloxacin antibiotic. This was attributed to the composite construction of Z-type heterojunction by BiPO₄ and Bi₂WO₆, which enhanced its redox capacity and consequently the degradation of CIP. In the meanwhile, XRD, FTIR, XPS, SEM, TEM, EIS, N₂ adsorption–desorption, and UV–vis DRS were used to characterize the composites’ structure and photoelectric characteristics. The synthesized materials had good stability and great purity, according to the results. Furthermore, EPR and free radical trapping tests demonstrated that the primary active ingredients for CIP degradation were h⁺ and ·O₂⁻. The final degradation products of CIP were detected by LC–MS, and it was determined that the degradation products were small molecules, and thus their degradation pathways were analyzed.

Pharmaceutical contaminants, particularly ciprofloxacin (CIP), pose significant ecological and health threats due to their persistence in aquatic environments and resistance to conventional water treatment methods. This study addresses the growing threat of pharmaceutical contaminants, specifically the antibiotic CIP, in wastewater. We developed a novel CQDs/N-WO₂ nanocomposite by coupling carbon quantum dots (CQDs) with nitrogen-doped tungsten dioxide (N-WO₂) via a synergistic hydrothermal-ultrasonication method. The key innovation of this work lies in the strategic electronic engineering of the material: nitrogen doping effectively narrows the band gap of WO₂ to enhance visible-light absorption, while the integration of CQDs creates a unique heterojunction that acts as an electron bridge, drastically improving charge separation and migration. This synergistic effect was confirmed through a combination of spectroscopic analysis, electrochemical measurements, and First-principles Density Functional Theory (DFT) calculations, which revealed enhanced light-harvesting and prolonged charge-carrier lifetimes. When applied to CIP degradation under ultraviolet–visible light (UV–vis), the optimized CQDs/N-WO₂ nanocomposite demonstrated exceptional performance, achieving a remarkable 98.3% removal efficiency, significantly outperforming its individual components. Mechanistic studies demonstrate superoxide and hydroxyl radicals as the primary active species, and a direct S-scheme charge transfer pathway was proposed to explain the superior photocatalytic activity. Furthermore, the composite exhibited excellent stability and reusability over multiple cycles. This work not only presents a highly efficient photocatalyst but also provides a fundamental understanding of interface engineering, offering a promising strategy for developing advanced materials for the remediation of pharmaceutical contaminants in water.

Graphical abstract

This study introduces a novel CQDs/N-WO₂ nanocomposite synthesized through a synergistic hydrothermal–ultrasonication approach for the efficient photocatalytic degradation of ciprofloxacin (CIP) in wastewater. Under optimized conditions, the composite achieves a high photodegradation efficiency of 98.3%, significantly surpassing the performance of its individual constituents. Exhibiting excellent reusability and structural stability, this photocatalyst offers a sustainable and effective strategy for the removal of persistent pharmaceutical contaminants from aquatic environments.

Graphitic carbon nitride (g-C₃N₄) was synthesized by applying a thermal treatment using waste melamine–formaldehyde product as a precursor. Photocatalytic antibiotic degradation performances of g-C₃N₄ was investigated. To enhance the photocatalytic activity of g-C₃N₄, the heat treatment temperature was varied as an experimental variable during the synthesis of g-C₃N₄, and different proportions of urea and silica template materials were separately mixed with the precursor before the heat treatment. A higher degree of crystallization was obtained as the heat treatment temperature was increased. According to FTIR analysis, it was understood that g-C₃N₄ was obtained more successfully at the heat treatment temperature of 650 °C. Mixing the precursor with urea and silica template did not significantly affect the chemical structure of the resulting g-C₃N₄. Mixing waste melamine–formaldehyde product with silica template gave rise to approximately sixfold expansion in the BET surface area of g-C₃N₄. It was determined that the g-C₃N₄ particles obtained by mixing waste melamine–formaldehyde product with urea and silica template turned from irregular blocks to spherical structures and the particle size decreased. By mixing waste melamine–formaldehyde product with urea and silica template, the photocatalytic antibiotic degradation efficiency of the resulting g-C₃N₄ was enhanced. The highest photocatalytic degradation efficiency (41.9%) was obtained on g-C₃N₄ synthesized from waste melamine–formaldehyde precursor containing urea and silica template under UV light irradiation for 120 min. It was attempted to produce high-value-added photocatalyst from waste melamine–formaldehyde material, reflecting the originality of the present study.

Inorganic micro- and nanoparticles are promising photocatalysts for removing toxic dyes from aqueous media. However, their dispersion in water and subsequent separation after the photocatalytic process remain challenging. In this study, MoS₂, a transition metal disulfide, was successfully dispersed in a water–ethanol mixture with the help of polyvinylpyrrolidone (PVP) and immobilized in a polyacrylamide (PAM) hydrogel to be easily separated from the medium after photodegradation. The resulting composite material was characterized, and its photocatalytic performance against methylene blue dye was studied. Optimal photocatalytic degradation was achieved at pH 9.0, using 40 mg of MoS₂ and 1.0 g of the composite hydrogel, resulting in a dye degradation efficiency of approximately 88.6% within 120 min. Kinetic studies indicated that the photodegradation of methylene blue dye followed second-order kinetics (R² = 0.989). Radical scavenging experiments revealed that superoxide radicals (left( { cdot {text{O}}_{2}^{ - } } right)), hydroxyl radicals (left( { cdot {text{OH}}} right)), and holes (h⁺) played predominant roles in the degradation process. Additionally, the composite hydrogel demonstrated promising reusability, retaining over 60% of its removal efficiency after four successive photocatalytic cycles.

Graphical Abstract

A palladium-catalyzed oxidative intramolecular cross-dehydrogenative coupling (CDC) strategy has been developed for the efficient synthesis of a novel class of polycyclic fused heterocycles, namely 9-tosyl-9H-indolo[3,2-c][1,2,3]triazolo[1,5-a]quinolines. This synthetic approach involves a sequential process consisting of Sonogashira coupling, cyclization, and oxidative C–H/C–H cross-coupling between indole and triazole moieties to deliver the desired fused products. The protocol proceeds under mild reaction conditions, utilizing palladium acetate as the catalyst, copper acetate hydrate as the oxidant, and acetic acid as an additive in DMF, enabling efficient annulation to construct complex molecular frameworks in moderate to good yields. A diverse range of substrates were explored to evaluate the scope and functional group tolerance of this method. The structures of the synthesized compounds were fully characterized by NMR spectroscopy, high-resolution mass spectrometry (HRMS), and single-crystal X-ray diffraction analysis. This methodology offers several advantages, broad substrate scope, operational simplicity, and avoidance of pre-functionalized substrates. Overall, this work expands the synthetic utility of palladium-catalyzed CDC reactions for the efficient construction of structurally complex fused polycyclic heteroaromatic compounds, which are of potential interest in pharmaceutical chemistry, materials science, and optoelectronic applications.

Graphical abstract

The design of cooperative catalytic systems inspired by nature represents a significant advancement in organic synthesis. In this research, the selective aerobic oxidation of primary and secondary alcohols to the corresponding carbonyl compounds was investigated using molecular oxygen as a green oxidant in the presence of a heterogeneous biomimetic catalytic system consisting of palladium, a sandwich-type polyoxometalate [(OCe)₃(PW₉O₃₄)₂]¹²⁻, and hydroquinone (HQ). In the first method, palladium nanoparticles were immobilized on siliceous mesocellular foam (MCF), while the polyoxometalate (POM) was supported on Nd-doped TiO₂ nanoparticles. Then, the aerobic oxidation of alcohols to the corresponding carbonyl compounds was investigated in the presence of the Pd@MCF/POM@TiO₂/HQ catalytic system in THF solvent at 40 °C. In the second method, both palladium and polyoxometalate were simultaneously immobilized on MCF and POM-Pd@MCF/HQ was used as an efficient biomimetic catalytic system. The second catalyst showed better performance with yields of 84–97% with TOF values up to 111 h⁻ ¹ in water as solvent at room temperature. Furthermore, the POM-Pd@MCF/HQ system showed the ability to be used for up to 8 consecutive applications with minimal decrease in its catalytic efficiency, indicating its structural stability and recyclability. The Pd@MCF, POM@TiO₂ and POM-Pd@MCF compounds were identified and confirmed by various techniques.