Research on Chemical Intermediates最新文献

Photocatalytic and photoelectrochemical (PEC) water splitting are considered key technologies associated with the future implementation of artificial photosynthesis. Since the dawn of this research field, various chemical and physicochemical phenomena characteristic of semiconductor/liquid interface have been reported. Meanwhile, in recent studies, photocatalyst and photoelectrode materials are generally being developed under the following assumptions: 1) The basic principles involved in photocatalytic and PEC reactions represent a combination of photovoltaics and electrolyzers on the microscopic scale and can thus be explained separately by analogy to photovoltaic physics and electrochemistry. 2) Effective utilization of the energy of photons for chemical reactions critically depends on the development of superior solid materials, including semiconductor photocatalytic particles and/or cocatalyst nanoparticles. But are these assumptions valid? This review highlights the important contribution of physicochemical phenomena in water, which have tended to be overlooked, during photocatalytic and PEC reactions. The benefits of a buffered aqueous solution during water splitting, which include accelerated proton-related mass transfer and a suppressed local pH gradient in the vicinity of the active sites, are summarized. In addition, a possible interaction between electronic band structures inside the semiconductor photocatalytic materials and transient physicochemical phenomena in water is proposed.

Recent developments have brought the Nickel-Molybdenum oxide hybrid system into the spotlight as a scalable and earth-abundant functional oxide electrocatalyst for the hydrogen evolution reaction via electrochemical water splitting. Herein, we examine the photoelectrochemical activity of NiO/MoO₂ hybrid nanostructure as an in situ grown thin film on fluorine-doped tin oxide (FTO), using a facile hydrothermal method while varying the weight percentage (wt%) of Ni as a pioneering attempt. Our findings reveal a captivating behavior of NiO/MoO₂ hybrid with metallic characteristics, alongside an observed photocathodic response indicated by a negative photocurrent, attributed to the synergistic effect. Moreover, the as-synthesized NiO/MoO₂ hybrid, H₂-annealed at 500ºC, achieved a fourfold improvement in average PEC performance from 5 µA/cm² to 20 µA/cm² compared to the NiO/MoO₂ hybrid/FTO under illumination. Overall, the result indicates Nickel oxide plausibly forming localized surface states, enabling light absorption without affecting the bulk properties.

Graphical Abstract

NiO/MoO2 hybrid nanotructures grown on FTO showing enhanced photoelectrochemical activity

Light–matter interaction between molecular vibrational modes and electromagnetic modes of Fabry–Perot cavity leads to the formation of vibrational strong coupling states showing the hybridization of molecules via vacuum fluctuations characterized as polaritons. However, how thermal modulation on the cavity properties influences polariton behavior remains unclear. We developed a temperature-tunable and optically stable Fabry–Perot cavity that enables reproducible observation of temperature-dependent light–matter interaction. We conducted in situ infrared spectroscopy of water over a temperature range of 10–40 °C. The characteristics of the cavity mode, such as resonance wavenumber, transmittance and finesse, were quantitatively tracked as functions of temperature to identify the deviation from an ideal cavity mode. The optical properties of polaritons were also characterized to find the correlations with the cavity mode. We found that the intensity of the upper polariton correlated moderately with finesse of the cavity defined as symmetry factor, whereas that of the lower polariton showed minimal dependence. This behavior can be explained by the positive detuning of the coupled cavity mode, where the upper polariton acquires more photonic character, and the lower polariton becomes more matter-like. These results demonstrate that the designed FP cavity enables accurate probing of polariton-cavity mode correlations under thermally modulated conditions.

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We present a Fabry–Perot cavity platform that allows controlled investigation of the temperature dependence of vibrational strong coupling. This spacer-free design provides continuous, stable IR measurements exceeding one hour, offering a robust tool to study polaritonic states under thermal modulation.

Water oxidation is a key half-reaction in artificial photosynthesis, and metalloporphyrin complexes have emerged as promising molecular catalysts owing to their well-defined coordination geometry and redox-active nature. Metalloporphyrin systems based on main-group metal ions such as Al³⁺, Si⁴⁺, Ge⁴⁺, and Sn⁴⁺ have been extensively studied for the direct two-electron oxidation of water initiated by one-electron oxidation; however, indium-based porphyrins remain largely unexplored. Herein, we report the synthesis and characterization of two indium (III) porphyrins—5,10,15,20-tetrakis(4-pyridyl)porphyrinate indium (III) (InTPyP) and its N-methylated derivative, 5,10,15,20-tetrakis(N-methyl-4′-pyridiniumyl)porphyrinate indium (III) (InTMPyP). These compounds were designed as analogs to previously reported aluminum porphyrins. A comparative investigation of their electronic, photophysical, and photocatalytic properties was conducted, highlighting the potential of indium-based systems for photo-driven catalytic reactions.

Photochromic compounds can be classified into two categories. One is thermally irreversible (P-type) and the other thermally reversible (T-type). Although diarylethenes are generally P-type, a certain environmental modification such as the addition of specific chemicals can change it into the T-type. For example, the addition of Brønsted acid to a diarylethene possessing an amino group is known to change the reaction mode of photochromism. However, in order to restore its P-type photochromism, a scavenger of the acid is required. We have disclosed here that the P-type/T-type switching of diarylethenes can be achieved by the photochromic reaction of a coexisting spiropyran which can generate a strong acid by photoirradiation. When it takes the thermally stable merocyanine (mc) form, it works as a weakly acidic phenol. On the other hand, when it takes the spiropyran (sp) form generated by visible light irradiation, it works as a strongly acidic iminium sulfonate. Protonation to the accompanying diarylethene changes it from P-type to T-type. When the sp form thermally returns to the mc form, the P-type nature of the diarylethene is restored again. Thus, we have achieved the all-optical switching between the P-type/T-type photochromic reaction modes of diarylethenes. These procedures do not require the addition or removal of any agents from the photochromic system.

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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.

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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.