Research on Chemical Intermediates最新文献

In this study, a mild and efficient solvent-free synthesis strategy was developed for the preparation of N-benzylidenebenzylamine via selective catalytic oxidation of benzylamine with oxygen over a composite MoO₃/SiO₂ catalyst. The result demonstrate that the 20%MoO₃/SiO₂ catalyst shows exceptional catalytic performance and stability. Even after five consecutive reaction cycles, the catalyst maintains a benzylamine conversion exceeding 97% and a N-benzylidenebenzylamine selectivity of 96%. Experiment and characterization results reveal that surface hydroxy groups of the MoO₃/SiO₂ play a critical role in the catalytic activation of benzylamine. Moreover, the existence of oxygen vacancy can facilitate the activation of oxygen. Finally, a plausible reaction pathway for the catalytic oxidation of benzylamine to N-benzylidenebenzylamine over MoO₃/SiO₂ is proposed. This study employs a cost-effective, simple, and highly active supported MoO₃/SiO₂ catalyst to selectively oxidize benzylamine into N-benzylidenebenzylamine in a solvent-free environment, demonstrating broad industrial application potential.

Graphical abstract

A cost-effective and high photocatalytic degradation for tetracycline novel bismuth and hollow cerium oxide composite materials (Bi/h–CeO₂) photocatalyst was prepared. Hollow cerium oxide microspheres (h–CeO₂) were prepared using the traditional templating method, and the Bi/h–CeO₂ was prepared from h–CeO₂ and bismuth nitrate pentahydrate in different molar ratios by the hydrothermal process. Based on the material morphology characterization and the photocatalytic degradation performance of the sample, the results clearly indicated that the addition of nanostructured Bi significantly improved the photocatalytic property of h–CeO₂. Additionally, the 0.01Bi/h–CeO₂ photocatalyst exhibited maximum photocatalytic activity and the degradation efficiency can attain 90.2% after 30 min of irradiation. A potential mechanism has been suggested for the photocatalytic degradation of tetracycline (TC) using Bi/h–CeO₂ under visible light.

Tetracycline (TC) has the characteristics of widespread use and environmental persistence, and has become a widely residual high ecological risk pollutant. In this study, we developed a natural suspended sediment (SS)-based adsorption-catalysis bifunctional system, achieving peroxymonosulfate activation and used for efficient removal of TC. Under optimized reaction conditions (pH = 7.0, [peroxymonosulfate] = 0.4 mM, SS = 2.5 g/L, [TC]₀ = 50 mg/L), the TC removal efficiency reaches 83.9%. Adsorption analysis shows that TC adsorption by SS follows a pseudo-second-order kinetic model (R² > 0.99), with a maximum theoretical adsorption capacity of 237.51 mg/g. The adsorption process combines monolayer and multilayer mechanisms. X-ray photoelectron spectroscopy (XPS) analysis and electron paramagnetic resonance (EPR) detection confirm that Fe active sites in SS facilitate electron transfer pathways for peroxymonosulfate activation, with singlet oxygen (¹O₂) identified as the dominant reactive species responsible for TC degradation. Liquid chromatography-mass spectrometry (LC–MS) analysis elucidates three major TC degradation pathways: hydroxylation, demethylation, and demethyleneation, ultimately yielding low-toxicity or non-toxic small organic molecules and inorganic products. The SS/peroxymonosulfate system achieves a TC removal efficiency exceeding 80% across a pH range of 4–11 and demonstrates strong adaptability to TC concentrations ranging from 10 to 110 mg/L. Inorganic anions and natural organic matter (humic acid, HA) affect TC removal to varying degrees. This system effectively reduces the expression levels of antibiotic resistance genes (ARGs) in sediments by 12–17%, suggesting its suitability for the in situ remediation of antibiotic-contaminated water. Furthermore, it offers potential for the development of SS-based advanced oxidation processes (AOPs) for environmental applications.

In this study, porous MoS₂ nanoflowers (NFs) were synthesized via a facile hydrothermal approach and evaluated for their photocatalytic activity toward the degradation of methylene blue (MB) under simulated sunlight. The as-prepared MoS₂ NFs exhibit a hierarchical structure composed of ultrathin nanosheets with abundant surface area and active edge sites, facilitating efficient light absorption and charge separation. Photocatalytic experiments revealed a high degradation efficiency of 98.30% in the first cycle and excellent reusability, retaining 93.30% efficiency after three cycles. Radical scavenging tests identified superoxide radicals (O₂^·−) as the dominant reactive species involved in the degradation mechanism, supported by contributions from hydroxyl radicals (^·OH) and photogenerated holes (h⁺). The enhanced performance is attributed to the high crystallinity, large surface-to-volume ratio, and improved charge carrier dynamics enabled by the porous nanoflower architecture. These results highlight the potential of MoS₂ nanostructures as efficient and stable photocatalysts for practical wastewater treatment applications under solar irradiation.

⁵⁷Fe–N–C electrocatalysts were synthesized via ultrasonic treatment and electron beam (e-beam) irradiation, enabling rapid nanoparticle formation under mild conditions. Mössbauer spectroscopy was used to analyze the oxidation and spin states of Fe–N₄ species. The ⁵⁷Fe-labeled samples prepared using e-beam irradiation exhibited three Fe(II)–N₄ configurations: low-spin (D1), medium-spin (D2), and high-spin (D3), observed at 4.2 K. A higher proportion of low-spin Fe(II)–N₄ sites strongly correlated with improved oxygen reduction reaction (ORR) activity. Notably, e-beam irradiation promoted the selective formation of these catalytically active low-spin sites, offering a scalable and efficient synthesis strategy.

The aim of this study is to investigate the characterization and synthesis of modified multi-walled carbon nanotubes (MWCNT) with PdCl₂. A novel, eco-friendly, and solvent-free method for synthesizing various xanthene dione derivatives has been developed, utilizing Pd/MWCNT as a heterogeneous and reusable nanocatalyst. This green procedure offers several advantages, such as excellent product yields, solvent-free conditions, straightforward workup, short reaction times, high catalytic activity, and the ability to reuse the nanocatalyst. Additionally, the catalyst demonstrated impressive recyclability, maintaining its efficacy even after five reaction cycles. A hot filtration experiment confirmed the heterogeneous nature of the catalyst, as no leaching was detected throughout the reaction procedure.

La₂CuO₄/WO₃-based hetero-system catalyst was applied for the sunlight-driven photodegradation of Acid Blue 9 (AB-9). The mass ratio (La₂CuO₄/WO₃) was optimized to achieve a complete color removal of AB-9 under specific conditions, including solar illumination, pH (~ 8), a temperature of 25 °C, and a catalyst concentration of 1 mg/mL. Comprehensive physical and optical characterizations of p-type La₂CuO₄ and n-type WO₃ were conducted using XRD, UV–visible spectroscopy, SEM, and BET surface area analysis. La₂CuO₄/WO₃ hetero-system exhibits a band gap of 1.45 eV (La₂CuO₄), while the WO₃ had a band gap of 2.49 eV, both displaying direct optical transitions. Capacitance–potential (C⁻²–E) measurements gave the flat band potentials of − 0.41 V_SCE, La₂CuO₄, and 0.44 V_SCE, WO₃. The BET analysis revealed a specific surface area of 31.2 m²/g and a pore volume of 0.15 cm³/g for the La₂CuO₄/WO₃ hetero-system. Upon visible light, electrons are excited from the conduction band of La₂CuO₄ (− 0.44 V_SCE) to the lower-energy conduction band of WO₃ (0.1 V_SCE). This process enhances the charge carrier separation, effectively accelerating AB-9 degradation. The photodegradation kinetic data of AB-9 were well fitted by the Langmuir–Hinshelwood (L–H) model, confirming a pseudo-first-order reaction characterized by an apparent rate constant of 0.014 min⁻¹ (t_1/2 = of 55 min). Overall, the La₂CuO₄/WO₃ hetero-system demonstrates high photocatalytic efficiency for AB-9 degradation under natural sunlight, highlighting its potential for sustainable water treatment applications.

The present work aims to develop flexible polymer blend nanocomposites with enhanced thermal, mechanical, and dielectric properties for potential energy storage applications. To achieve this, chlorinated polyethylene (CPE)/ethyl vinyl acetate (EVA) blend nanocomposites reinforced with nickel oxide (NiO) nanoparticles were prepared using a solvent-free two-roll mill mixing process. The successful formation of blend nanocomposites was confirmed through Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) analyses. FTIR analysis confirmed the incorporation of NiO through the appearance of new vibrational bands, while XRD revealed its characteristic crystalline reflections. UV–Vis spectra exhibited bathochromic shifts with increasing NiO loading, suggesting strong interfacial interactions. FE-SEM and HR-TEM images revealed uniform dispersion of nanoparticles at 5 wt% loading, whereas higher contents led to agglomeration. Thermogravimetric analysis (TGA) demonstrated that incorporating NiO significantly improved the thermal stability of the blend nanocomposites. Extensive dielectric studies across wide temperature and frequency ranges exhibited significant enhancements in dielectric constant, electric modulus, and AC conductivity. The composite with 5 wt% NiO exhibited the highest performance, with a dielectric constant of 87 and an AC conductivity of 3.38 × 10⁻⁶ S/cm at 10⁶ Hz. Mechanical testing showed remarkable improvements, with tensile strength, tear strength, and impact strength increasing by 74.1%, 116.85%, and 55.7%, respectively, accompanied by a hardness increase from 59 to 66. These findings demonstrate that EVA/CPE/NiO nanocomposites exhibit an optimal balance of structural integrity, thermal stability, and electrical performance, making them promising candidates for flexible energy storage devices.

Photocatalytic hydrogen production from anhydrous methanol is dynamically regulated by oxygen concentration, challenging the conventional paradigm that oxygen suppresses H₂ evolution. This study demonstrates that introducing 10 vol% oxygen into the Pt/TiO₂ system enhances the hydrogen production rate from 289.17 to 1189.46 μmol/h by acting as an electron acceptor to accelerate interfacial charge transfer at the semiconductor-cocatalyst-solution interface. Under anaerobic conditions, hole-driven methanol oxidation dominates the reaction, yielding ~ 100% formaldehyde selectivity. Limited proton generation arises from methanol’s low ionization degree, hindering hydrogen evolution. Oxygen addition shifts the mechanism to superoxide radical (·O₂⁻) dominance, reducing photogenerated electron accumulation and promoting carrier separation. This overcomes the kinetic limitation of proton deficiency in anhydrous media. Excess oxygen (> 10 vol%) triggers over-oxidation of methanol/formaldehyde to formic acid, CO, and CH₄, decreasing H₂ selectivity. Radical scavenging experiments reveal that ·O₂⁻ becomes the primary reactive species with oxygen, outperforming holes and hydroxyl radicals. These findings establish oxygen as a dual-function regulator of electron transfer and product selectivity, offering strategies for optimizing photocatalytic hydrogen evolution systems.

The electrocatalytic reduction of NO to NH₃, driven by renewable electricity, offers a method to produce NH₃ with added chemical value while being environmentally friendly and sustainable. This process represents a promising approach to reducing NO emissions with extensive research potential. Therefore, it is extremely urgent to develop electrocatalysts with high activity, selectivity and stability. In this study, density functional theory calculations were employed to investigate the catalytic activity of 3d transition metal atoms doped with C and N vacancies on the surface of C₃N to form single-atom catalysts (TM-C@C₃N and TM-N@C₃N). Through the analysis of the thermodynamic and electrochemical stability, the adsorption capacity of NO, the free energy barriers, and the inhibition of hydrogen evolution reaction, it was determined that V-C@C₃N and V–N@C₃N have the potential to be highly active electrocatalysts with the limiting potentials of − 0.450 and − 0.386 V, respectively. Furthermore, the reason for the high activity was understood through the analysis of the electronic properties of the potential-determining step. Therefore, the catalyst proposed in this study is expected to directly convert the air pollutant NO into valuable NH₃.