Catalysis Letters最新文献

This work aims to enhance TiNT’s light absorption capacity and PEC hydrogen production efficiency through simultaneous modification with organic compounds and Ag nanoparticles. By comparing three organics (dopamine, ascorbic acid, benzoic acid), we found that π-π stacking between aromatic groups on TiNT and hydroxyl-bearing molecules enhances dopamine deposition, which is critical for subsequent Ag nanoparticle modification. Co-modification with dopamine and Ag nanoparticles (TiNT-Dopamine-Ag) enhances both visible light absorption and PEC activity. Compared to TiNT directly modified with Ag (TiNT-Ag), TiNT-Dopamine-Ag with equivalent Ag concentration exhibited a 3.2-fold higher hydrogen production efficiency.

Metal–organic frameworks (MOFs) derived nanomaterials were synthesized using Ce, Fe, and Cu metal precursors with trimesic acid (TMA) as the organic linker via a green synthesis route, and their structural, morphological, and catalytic properties were systematically investigated. X-ray Diffraction (XRD) and Fourier-Transform Infrared spectroscopy (FTIR) analysis confirmed the formation of crystalline, phase-pure frameworks with characteristic metal–ligand coordination. In contrast, Brunauer-Emmett-Teller (BET) and Barrett, Joyner, and Halenda (BJH) analyses revealed mesoporous structures with distinct surface areas and pore volumes. Field-Emission Scanning Electron Microscope (FE-SEM) analysis demonstrated morphology-dependent features, including porous rods (Ce-TMA), coral-like aggregates (Fe-TMA), and cuboidal crystalline structures (Cu-TMA). Catalytic performance tests revealed that Fe-TMA achieved the highest chlorpyrifos degradation efficiency (99.6%) through efficient Fe²⁺/Fe³⁺ redox cycling and adsorption-driven radical generation, followed by Ce-TMA (98.5%) and Cu-TMA (82%). Kinetic analysis revealed that pseudo-first-order and intraparticle diffusion models best describe the degradation process, underscoring the combined roles of adsorption and surface reactions. For carbon monoxide (CO) oxidation, Cu-TMA outperformed the other catalysts, achieving the lowest temperature (T₅₀ = 352 °C) and the highest pre-exponential factor. In contrast, Fe-TMA exhibited moderate performance, whereas Ce-TMA was limited by its low active site density. These findings confirm that TMA-linked MOFs synthesised through green chemistry are a sustainable, multifunctional catalysts for addressing both water and soil pollution (chlorpyrifos degradation) and air pollution (CO oxidation), with Fe-TMA excelling in wastewater treatment and Cu-TMA proving superior in emission control.

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The utilization of visible light to carry out organic transformations is useful from the viewpoint of solar energy conversion. In the present work, magnetite nanoparticles (Fe₃O₄ NPs) were synthesized and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), UV-visible diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy. The material was found to possess cubic spinel phase. The particles were found to be 20 to 45 nm in size. The band gap of the semiconductor was determined as 2.31 eV using Tauc’s plot. The Fe₃O₄ NPs were employed as a photocatalyst for studying the oxidation of phenol under visible light irradiation. Nearly, 69% phenol was converted to product(s) during 30 min of irradiation. The photocatalytic process was found to follow first-order kinetics with a rate constant of 0.039 min^− 1. The product of the visible light induced oxidation of phenol was identified as maleic acid based on the liquid chromatography-mass spectrometry (LC-MS) analysis. A probable reaction mechanism for the formation of maleic acid from phenol has been presented. The effect of key parameters such as solution pH and catalyst loading on the conversion efficiency of phenol were investigated. The Fe₃O₄ NPs were found to possess good catalytic activity for three cycles.

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In this work, a novel core-shell magnetic composite, Fe₃O₄@resorcinol-formaldehyde (RF) functionalized with a 1,4-diazabicyclo[2.2.2]octane ionic liquid (MRF/DABCO-IL), was successfully synthesized and comprehensively characterized by XRD, EDX, TGA, FE-SEM, TEM, VSM, and FT-IR analyses. These characterizations confirmed the formation of the core-shell structure and the successful incorporation of DABCO-IL functional moieties. The catalytic efficiency of MRF/DABCO-IL was evaluated in the Knoevenagel condensation reaction under both ultrasonic and thermal conditions. Remarkably, under ultrasonic irradiation, target products were achieved in excellent yields (90–97%) within only 4–16 min at room temperature, while conventional heating afforded comparable yields (89–94%) in 8–25 min. The application of ultrasonics not only enhanced the reaction rate and yield but also enabled the process to proceed under milder and greener conditions. Moreover, the catalyst readily recovered via an external magnetic field and reused for at least eight consecutive cycles without a significant loss in activity, highlighting its potential as a robust and sustainable catalytic system.

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NO hydrogenation by using H₂S as a hydrogen source not only can generate NH₃ but also reduce the pollution. Here, by using the first principles calculations, we investigated the dissociations of NO and H₂S, the hydrogenations of N* adatoms, and the formation of NH₃ via thermal catalysis on Aluminum (Al) crystal surfaces. The molar ratio of NO to H₂S has strong influence on the reaction path and reaction energy barrier. On clean Al(111), the energy barrier for the rate determining step (NH₂→NH₃) is 1.42 eV at the ratio of 1:2, while it is only 0.56 eV at the ratio of 1:3. After NH₃ desorption, NO dissociation and N* hydrogenation proceed on the O* and *SH covered surface and the corresponding energy barriers are 0.59 and 0.40 eV, respectively. Thus, the NO to NH₃ production can be continued. This study offers valuable insights for designing high-performance main group metal catalysts for NO reduction and H₂S removal.

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A PVDF-HFP-based composite porous membrane was successfully fabricated with the strategic incorporation of ZnO rods preferentially aligned along the c-axis. This unique structure ensures the uniform dispersion and adequate exposure of ZnO nanorods within the PVDF-HFP matrix while maintaining the interconnectivity of the porous membrane, which effectively increases active interfaces and strain transfer efficiency. Under coupled light and ultrasound irradiation, the PHZ-0.15 composite membrane demonstrated optimal performance, achieving an H₂O₂ production rate of 862 µmol·cm^− 2·h^− 1. The composite also exhibited excellent cycling stability. Trapping experiments revealed that the synergy between ultrasound-induced piezoelectric polarization and photogenerated carrier separation significantly promotes the two-electron reduction of O₂ via conduction band electrons, with electrons and superoxide radicals (·O₂⁻) identified as the primary active species. This study provides a new strategy and mechanistic insight for developing efficient piezo-photocatalytic materials toward sustainable H₂O₂ production.

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In this study, Mn_xCe_(1−x) mixed oxides (x = 0, 0.25, 0.50, 0.75, and 1.00) were synthesized using a straightforward redox method, and the effect of the Mn–Ce composition on the total oxidation of carbon monoxide (CO) was examined. Under standard reaction conditions of 1% CO and 4% O₂, the light-off temperatures (T_50%), which indicate the temperature at which 50% of the CO conversion occurs, of Mn–Ce mixed oxide increased in the sequence: 0.25 < 0.50 < 0.75 < 1.00 (MnO₂) < 0 (CeO₂). Although Mn_0.25Ce_0.75 stands out for its superior catalytic performance, this efficiency notably diminishes when CO₂ and H₂O vapors are introduced into the reactants. This decline is attributed to the competitive adsorption of CO₂ and H₂O on the active sites, which impedes the oxidation of CO. Various techniques have been employed to understand the physicochemical properties of Mn–Ce mixed oxides. The analysis revealed that incorporating an appropriate amount of Mn into Ce yielded a substantial quantity of labile oxygen species, enhancing the reducibility of the system, thereby improving its catalytic performance. Although improving H₂O resistance is essential, Mn–Ce mixed oxides present a promising alternative to noble-metal-based oxidation catalysts.

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A copper tuned phosphotungstic acid (Cu-PTA) supported on TiO₂ catalyst is found to be highly stable, active and chemo-selective dehydration of glycerol to acrolein during gas phase under atmospheric pressure. A range of catalysts was produced by adjusting the active phase of Cu-PTA loadings between 10 and 40 wt% on the titania support. The characterization data provides information of Keggin ion structure was maintained even after higher active phase loading and moderate acidity inclined with loadings. FT-IR spectra results suggest, Keggin ion was retained after regeneration of catalyst. The catalytic properties are affected by active phase Cu-PTA loading, calcination temperature, reaction temperature, glycerol concentration, time on stream and regeneration studies. The overall optimized catalysts, 30 wt% catalyst possess higher amount moderate acidic sites and total acidity results 87% acrolein selectivity with 98% glycerol conversion at 325 °C in atmospheric pressure. The regenerated catalyst exhibits similar catalytic performance compared to fresh catalyst is because of minimal change in acidity of catalyst after regeneration.

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Scheme 1: Glycerol to acrolein over Cu1.5PW12O40 / TiO2 catalyst.