Catalysis Letters最新文献

In this study, Nickel-Aluminum Takovite (NiAl-Takovite) was developed as an effective heterogeneous catalyst for the synthesis of 3,4-dihydropyrimidin-2(1 H)-ones (DHPMs) through the Biginelli cyclocondensation reaction. The catalyst was prepared using a coprecipitation method and characterized by TG-dTG, FT-IR, XRD, N₂ adsorption-desorption, and SEM-EDX analyses to examine its structure, microstructure, and composition. NiAl–Takovite exhibited excellent catalytic performance, facilitating the rapid synthesis of DHPMs derivatives with yields of up to 90%. The products were characterized by NMR spectroscopy and evaluated for their antimicrobial activity against bacterial and fungal species. The distinctive structural features of the catalyst, its surface basicity, and textural properties underlie its high efficiency, offering an environmentally friendly and sustainable strategy for the production of bioactive DHPMs as potential antimicrobial agents.

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Due to the high toxicity and low degradability of phenolic compounds, including hydroquinone (HQ), in environmental samples, there is a strong need for the development of efficient catalytic systems for the oxidation of hydroquinone to benzoquinone (BQ). Catalytic oxidation using nanoscale metal-based catalysts has been recognized as an effective approach for the removal of such contaminants. In this study, reduced graphene oxide–based iron oxide, iron nitride, and cobalt ferrite nanocomposites were synthesized using co-precipitation, pyrolysis, and hydrothermal methods. The obtained nanocomposites were characterized by UV–Vis spectroscopy, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, and field-emission scanning electron microscopy (FESEM). The catalytic performances of the synthesized nanocomposites toward the oxidation of hydroquinone to benzoquinone using H₂O₂ in aqueous solution were comparatively evaluated. The results indicated that the Fe₂N/CSrGO nanocomposite exhibited the highest activity under the investigated conditions, achieving an oxidation efficiency of 82.6% at pH 8 with a catalyst dosage of 20 mg after 120 min of reaction. The enhanced performance of Fe₂N/CSrGO is attributed to the combined contribution of the iron nitride phase and the nitrogen-doped rGO framework, which can facilitate electron transfer, as well as the mesoporous structure of the composite (specific surface area of 269.50 m² g⁻¹), which promotes accessibility of active sites. High-performance liquid chromatography (HPLC) analysis confirmed 100% selectivity toward benzoquinone. These findings suggest that rGO-supported iron nitride catalysts are promising candidates for selective hydroquinone oxidation in aqueous systems under mild conditions.

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In this work, Gd₂CuO₄, prepared by the nitrate method, exhibited a significant piezo-photocatalytic activity for the degradation of Rhodamine B (Rh B) under solar illumination. Structural and electrochemical analyses confirmed the formation of a tetragonal spinel phase with p-type semiconducting behavior and a narrow band gap of 1.37 eV, enabling efficient visible-light absorption. Additionally, the material demonstrated an excellent chemical stability over a wide pH range, along with favorable electrochemical characteristics, supporting its potentiality for Advanced Oxidation Processes (AOPs). Under photocatalysis alone, Gd₂CuO₄ achieved 63% Rh B degradation via superoxide radicals (O₂^⋅−). However, the introduction of piezo-photocatalysis (PPC) using Ultrasound Waves (USW, 60 kHz) significantly enhanced the oxidation efficiency to 90% within only 35 min., following a pseudo-first-order kinetic model with a half-life of 17 min. This enhancement is attributed to the material’s piezoelectric and ferroelectric properties, which promote the charge separation and accelerate Reactive Oxygen Species (ROS) generation. Additionally, the narrow band gap and negative conduction band improve solar energy utilization and facilitate oxygen reduction to reactive intermediates. Gd₂CuO₄ is found to be a highly efficient piezo-photocatalyst, with the synergy of piezoelectricity and photocatalysis enabling sustainable wastewater treatment.

In this study, a series of Co₃O₄/C₃N₄ composites with oxygen vacancies​ was successfully fabricated by incorporating varying loadings of Co₃O₄ onto g-C₃N₄, aiming to enhance the photocatalytic performance for H₂O₂ production. Among the prepared samples, the 20 Co₃O₄/C₃N₄ composite exhibited remarkable photocatalytic activity and stability. The superior performance is primarily attributed to the introduction of oxygen vacancies, which not only facilitated the migration and separation of charge carriers but also provided additional active sites for O₂ adsorption. The optimal 20 Co₃O₄/C₃N₄ sample achieved an H₂O₂ production rate of 174.2 µmol·g^− 1·h^− 1, which is 4.8 times higher​ than that of pure g-C₃N₄ (36 µmol·g^− 1·h^− 1). Linear sweep voltammetry (LSV) tests revealed a lower onset potential and a smaller Tafel slope​ for the 20 Co₃O₄/C₃N₄ electrode, indicating reduced overpotential and accelerated reaction kinetics. Furthermore, in situ infrared spectroscopy confirmed that the two-electron oxygen reduction reaction (2e⁻ ORR)​ served as the primary pathway for H₂O₂ generation in the Co₃O₄/C₃N₄ catalytic system. This work provides deep insights into the role of oxygen vacancies in photocatalytic H₂O₂ synthesis, offering experimental evidence and theoretical references for related research, and demonstrating potential for practical applications.

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Compositing g-C₃N₄ with Co₃O₄ at optimal loadings successfully introduced oxygen vacancies and constructed a Co₃O₄/C₃N₄ heterojunction. This strategic modification led to a substantial enhancement in the charge separation efficiency, thereby boosting the photocatalytic H₂O₂ production rate from 36 µmol·g^− 1·h^− 1 (pristine g-C₃N₄) to 174.2 µmol·g^− 1·h^− 1 for the optimal composite

Hydrogen production via water splitting has emerged as a viable strategy to address environmental degradation and energy crises, offering a sustainable route to clean energy. ZnFe-layered double hydroxides (LDHs) are regarded as promising electrocatalysts for overall water splitting due to their high activity and stability, yet their practical application is limited by poor electrical conductivity. Herein, we fabricate sulfur-doped ZnFe-LDH (S-ZnFe-LDH) ultrathin nanosheets on nickel foam as a bifunctional electrocatalyst. The S-ZnFe-LDH electrode exhibits good performance, requiring overpotentials of only 245 mV for the oxygen evolution reaction (OER) at 50 mA cm^− 2 and 142 mV for the hydrogen evolution reaction (HER) at 10 mA cm^− 2, along with good durability. When assembled into a two-electrode electrolyzer, it achieves 50 mA cm^− 2 at a low cell voltage of 1.80 V. In this work, Zn acts as a dynamically sacrificial species whose leaching kinetics are precisely regulated by S, creating and stabilizing catalytically vital cation vacancies. This S-induced stabilization effect effectively prevents the structural collapse typically associated with such cation leaching. This work provides a valuable reference for designing efficient electrocatalysts for integrated water splitting.

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The development of highly efficient non-precious metal catalysts for the hydrogen evolution reaction (HER) that can maintain stability at elevated current densities remains a significant challenge in advancing the industrialization of hydrogen production via water splitting. In this study, we successfully constructed a metal-organic framework (MOF)-derived nitrogen-doped CoO/Ni₂P three-dimensional self-supporting electrode on nickel foam (NF) using a hydrothermal phosphating strategy. This architecture leverages the three-dimensional framework of NF to mitigate the structural collapse of MOF materials during high-temperature heat treatment and to establish an effective conductive network. Structural characterization reveals that the three-dimensional porous channels of the electrode fully expose the active sites, while the synergistic effects of nitrogen doping and CoO/Ni₂P optimize the electronic structure of the Co active center, thereby significantly enhancing intrinsic activity. In a 1.0 mol/L KOH electrolyte, this electrode requires an exceptionally low potential of 39 mV and 187 mV to achieve current densities of 10 mA cm^− 2 and 650 mA cm^− 2, respectively, and it can operate stably for over 24 h at a high current of 650 mA cm^− 2 with negligible performance degradation. This study offers novel insights for the design of HER catalysts suitable for industrial applications.

Designing highly active non-noble metal catalysts for hydrogenating biomass-derived platform molecules remains a significant challenge. In this study, an efficient NiCo catalyst anchored on hollow mesoporous carbon spheres (Ni₁Co₁/HMCs) was developed, which achieves a cyclohexanol yield of ≥ 99.0% from phenol under mild reaction conditions (150 °C under 2MPa H₂ within 4 h). Comprehensive characterization techniques, including XRD, SEM, TEM, XPS characterizations confirm the formation of well-dispersed Ni-Co alloy particles, which are identified as the active centers responsible for the exceptional catalytic performance. Furthermore, the catalyst exhibits excellent recyclability, maintaining stable activity over five consecutive cycles, underscoring its potential for practical industrial applications.

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The carbonate industry is a high-emission process that generates large amounts of CO₂, whereas in-situ hydrogen-assisted pyrolysis is an effective technological strategy for reducing emissions. This study utilizes a kilogram-scale rotary kiln to simulate industrial-scale carbonate hydrogenation processes, taking the in-situ hydrogenation conversion of limestone as an example. By adjusting parameters such as the tilt angle, rotational speed, hydrogen flow rate and temperature of the rotary kiln, it was found that under conditions of 750 °C, a hydrogen flow rate of 2 L min^–1, a tilt angle of 2° and a rotational speed of 4 rpm, the CO selectivity in the rotary kiln reached 95.2%. This resulted in a CO generation rate of 6.96 mmol min^–1 and a total limestone pyrolysis reaction rate of 7.32 mmol min^–1. This outperformed the traditional fixed-bed reactor, which achieved a rate of 0.73 mmol min^–1 under the same conditions. Furthermore, kilogram-scale CaCO₃ pyrolysis was achieved. Characterization techniques such as XRD, XPS, SEM, and TEM confirmed that the hydrogenation pyrolysis produced CaO with high crystallinity. Furthermore, TG-MS and In situ FT-IR analyses further demonstrated that the introduction of hydrogen alters the carbonate decomposition pathway, thus reducing the reaction temperature and improving CO selectivity. This work investigates the process of in-situ hydrogen refining of carbonates in the rotary kiln. In addition to enhancing reaction performance, the process aligns with the existing cement clinker production process, providing a feasible pathway for the industrial scale-up and engineering application of this technology.

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The hydrogen-assisted pyrolysis of limestone was carried out in a rotary kiln reactor under conditions close to industrial applications, successfully achieving large-scale co-production of quicklime and CO at low temperatures.

To meet aviation decarbonization targets, efficient catalysts for bio-jet fuel are needed. Hydrodeoxygenation (HDO) is an indispensable step in converting lipid feedstocks to jet-range hydrocarbons, which critically depends on the pore architecture, acidity distribution and metal dispersion of the catalysts. In this work, a layered SAPO-11 (LS) molecular sieve was synthesized using the polyamine surfactant (C₂₂H₄₅-N(CH₃)-C₆H₁₂-N(CH₃)₂) as a micro-mesopore-directing agent. Ni species were introduced to obtain a series of Ni_x/LS catalysts with the Ni loadings of x wt% (x = 3.0, 6.0, and 9.0), in which Ni₆/LS exhibited the best HDO performance. Using methyl laurate (ML) as a model feedstock, at the optimized conditions of 360 °C, 2.0 MPa and a weight hourly space velocity (WHSV) of 6.0 h^− 1, the Ni₆/LS catalyst had the 99.6% conversion of ML with the 97.3% selectivity toward C₁₁-C₁₂ alkanes, surpassing the conventional Ni₆/microporous SAPO-11 (Ni₆/MS) catalyst and the literature-reported catalysts. The superior lipid HDO performance of Ni₆/LS was attributed that the layered architecture of LS provided a larger specific surface area and more mesoporous channels than MS, greatly promoting the high dispersion of Ni species.

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