Catalysis Letters最新文献

In this work, the catalytic conversion of furfural was found to follow both CTHs and etherification pathways in one-pot over multicationic inorganic perovskites (LaNi_1-xMo_xO_3±δ) as heterogeneous catalysts. The conversion of furfural (FA) into alcohols and ether functionalities using the as-synthesized perovskite catalysts showed good conversions that are above 80% and excellent selectivity towards the desired product. The LaMoO₃ catalyst was found to achieve the highest percentage conversion of 83%. Simple and multicationic inorganic perovskites were successfully employed in the transformation of furfural to produce β-methoxy-2-furanethanol. Furthermore, we postulate the hydrogenation of the keto-group to be the first step in the mechanism of the formation of β-methoxy-2-furanethanol and that its formation is characterized by rearrangement of the intermediate over the surface of the catalyst.

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Enhancing the performance of ruthenium (Ru)-based electrocatalysts for the alkaline hydrogen evolution reaction (HER) presents a significant challenge. Herein, titanium dioxide nanowire arrays decorated with ruthenium clusters were grown on carbon cloth (Ru-TiO₂ NWAs/CC) via a two-step hydrothermal method. The nanowire array structure increases the surface area of the substrate, allowing for more Ru clusters to be decorated, thereby improving catalytic activity. The resulting Ru₃–TiO₂ NWAs/CC catalyst exhibits prominent HER performance in 1.0 M KOH with overpotentials of 61 at 10 mA cm⁻² and a Tafel slope of only 47.4 mV dec⁻¹. Furthermore, it maintains outstanding stability under alkaline conditions for more than 10 h. The Ru clusters decoration enhances the TiO₂/CC kinetic, more active sites were exposed on nanowires of the surface and accelerated electron transport, thus reducing the charge transfer barrier. After the electrochemical test, the morphology and structure of Ru₃–TiO₂/CC remained largely unchanged, and the valence states of the elements remained stable. This work paves the road to exploiting highly active and cost-efficient electrocatalysts for alkaline hydrogen evolution.

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In this study, silicon carbide (SiC) was prepared from sol–gel process combined with subsequent carbothermal reaction. Then through hydrothermal method synthesized xFe/SiC-700 and 30Fe/SiC-T catalysts. The catalysts were characterized by XRD, SEM/TEM, XPS, and H₂-TPR. The ammonia decomposition performances of the catalysts were assessed in a fixed-bed reactor. Tests revealed that SiC has a high specific surface area and can evenly diffuse Fe₂O₃ nanoparticles, thus exposing more active sites and raising the adsorption capacity of catalysts surface. The interaction of Fe₂O₃ and SiC is stronger, the catalyst activity is better. The surface basicity of catalyst is higher, decomposition ability of ammonia is stronger. 30Fe/SiC-700 catalyst has the best activity among the synthesized catalysts for hydrogen production by ammonia decomposition. The ammonia conversion rate can reach up to 90.16%, and the hydrogen generation can rate reach up to 30.19 mmol·min⁻¹·gcat⁻¹ at 600 °C at 30,000 mL·gcat⁻¹·h⁻¹. Moreover, the catalytic activity is efficient and stable after continuous reaction at 600 °C for 160 h.

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Ammonia decomposition: The silicon carbide supported iron oxide catalyst was prepared, which effectively cracked ammonia to produce CO_X-free H₂.

The first zinc(II)-catalyzed approach towards an array of 2-aminobenzothiazole derivatives was successfully developed. In this process, the substrate 2-bromophenyl isothiocyanate was reacted with a range of amines, including aromatic and aliphatic (primary and secondary) and cyclic secondary amines, yielding the products in reasonably good amounts. The reactivity analyses of different amines revealed that cyclic secondary amines performed exceptionally well, providing excellent outcomes. Additionally, aliphatic amines also exhibited the capability to undergo the transformation successfully.

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We use density functional theory (DFT) to calculate the optimal parameters of atomic arrangement, energy level and electronic structure of sawtooth (n, 0) nanotubes in this paper. The strain energy and formation energy data show that the coiled process of nanotubes is endothermic, and the correlation value decreases with the increase of the radius. Our study shows that the band gap width of SiI₂ nanotubes first increases and then decreases with the increase of the nanotube radius. The band gap of SiI₂ nanotubes changes from indirect to direct after the single layer is rolled into nanotubes and have appropriate band gaps for absorbing visible light. In addition, it is speculated that the disparity between the effective mass of electrons and holes can reduce charge carrier recombination. Among them, the n value 10 ~ 50 nanotubes showed redox capacity between pH = 7 and 0, and the reducing capacity increased with the increase of tube radius. In conclusion, we believe that SiI₂ nanotubes have great application potential in photocatalytic water splitting.

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Visible light absorption indicate that SiI₂ nanotube should be effective photocatalysis for production of H₂ from splitting water

This work explored the possibility of doping MnO₂ structure simultaneously by cationic (Na⁺, Mg²⁺ or K⁺) and nitrogen species during its synthesis through gliding arc plasma route. Therefore, NaMnO₄, Mg(MnO₄)₂ or KMnO₄ precursor has been precipitated via plasmachemical reduction thanks to NO⋅ and NO₂⁻ respectively being short and long-lived species generated in plasma plume (gas phase) and plasma post-discharge (liquid phase). Physicochemical characterizations revealed nanostructured NaN–MnO₂, MgN–MnO₂ and KN–MnO₂ respectively with specific surface areas of 36, 110 and 116 m²/g, nitrogen atomic loading at surface of 0.6, 1.0 and 1.5%, and band gap values of 1.20, 1.30 and 1.45 eV. The three precursors with different cationic species allowed different nitrogen loading for their respective plasma-synthesized MnO₂, which led to the different values of band gap energy. An increase of the N-loading induced an increase of band gap energy and enlarged the absorption capability of MnO₂ from visible light to the UV region. Solar photocatalytic removal of TY revealed bleaching degrees of 53, 97 and 94% respectively for NaN–MnO₂, MgN–MnO₂ and KN–MnO₂ materials. This enlargement, together with the increased specific surface area of the plasma-synthesized N–MnO₂, led synergistically to an enhancement of its photocatalytic activity. This work highlights the usefulness of the synthesis via glidarc plasma, without any additional reagent, of MnO₂, as allowing cationic species insertion in their structure, and simultaneously their doping with different N-loading, so leading to different crystalline structures, and photocatalytic activities.

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In this work, we report a method of obtaining and characterizing (Fe, Pb) co-doped titanium oxide nanoparticles to study the influence of Fe³⁺ and Pb²⁺ doping on the photocatalytic and antimicrobial properties of TiO₂. The presence of dopant elements can provide electronic changes by promoting a decrease in the band gap or creating intra-band gap states, thereby allowing greater absorption under visible light irradiation and potentially increasing the efficiency for developing photocatalytic and antimicrobial applications. Therefore, co-doped Ti_1−x−yFe_xPb_yO₂ (x and y = 0, 0.01, 0.03, 0.07 mol) powders were successfully obtained in a single step by the sonochemical method (SM). The structural, morphological and optical properties were evaluated using X-ray diffraction (XRD), transmission electron microscopy (TEM), Field Emission Gun—Scanning Electron Microscopy (SEM-FEG) and UV–Visible spectroscopy (UV–Vis) techniques. The results showed the successful formation of the anatase phase of (Fe, Pb) co-doped TiO₂ by the SM with nanometric particles of irregular morphology. The photoluminescence exhibited low intensity for the co-doped samples, indicating a decrease in the recombination rate of the e−/h + electronic pair, which contributes to the photocatalytic efficiency. Optical measurements revealed a decrease in the band gap, providing possible energetic activation of these semiconductors by sunlight. The photocatalytic activity was estimated through the methylene blue dye (MB) degradation when exposed to UV light and Sunlight, and revealed that the type of radiation used to activate the photocatalysts influences the catalytic activity: T1F (Ti_0.99Fe_0.01O₂) and T1P (Ti_0.99Pb_0.01O₂) samples degraded the dye by 50% and 65% under UV light for 120 min, respectively, while the degradation under Solar irradiation was 98% and 99%, respectively. Antimicrobial properties were also investigated by agar diffusion method against E. coli (gram-negative) and S. aureus (gram-positive) bacteria and showed positive results of (Fe, Pb) co-doped TiO₂ samples compared to pure TiO₂. Accordingly, the results indicate that the co-doping of TiO₂ with Fe³⁺ and Pb²⁺ influences its potential application as photocatalysts and antimicrobial agents.

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Herein, Ag/TiO₂ NH₃-SCO catalyst was prepared by impregnation-rotary evaporation method with different calcination temperature and Ag loading content. The results of performance evaluation and characterization showed that the 10 wt% Ag/TiO₂ catalyst calcined at 500 °C showed the best comprehensive performance, with T₉₉ reaching 175 °C and N₂ selectivity reaching 80% at high temperatures. High-temperature calcination will lead to a significant decline in catalyst activity, accompanied by the transformation of TiO₂ from anatase to rutile phase and the obvious change and loss of Ag active sites, which greatly reduces the NH₃ adsorption and redox ability, but it can still maintain a high N₂ selectivity due to unchanged reaction mechanism. In addition, with the increase of Ag loading, excess Ag on Ag/TiO₂ will form metal clusters due to the lack of sufficient anchor points, which helps to improve NH₃-SCO activity. However, excessive Ag loading will reduce the specific surface area and acidic sites, and the Ag species on the catalyst surface will also change to the form of larger particles of Ag₂O, which will lead to the decline of catalytic performance.

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The catalytic oxidation of CO is a significant process for environmental and human health protection. The CuMnO_x (hopcalite) catalyst is a good candidate for the CO oxidation reaction, owing to advantages such as low cost and good catalytic activity at low temperature. In this study, a combination of reactive force field molecular dynamic simulations and density functional theory calculations was employed to investigate the CO oxidation reaction catalyzed by CuMnO_x. We examined the effect of three factors (oxygen content of CuMnO_x catalyst, pressure, and free O₂ concentration) on enhancing the CO conversion. The CuMnO₄ catalyst exhibited superior performance in the CO oxidation reaction. The main oxygen source of the oxidation product (CO₂) was found to be the lattice oxygen atoms of the CuMnO_x catalyst. The energy barrier of the oxidation reaction between CO and the lattice oxygens was relatively low, showing that this reaction was kinetically favored. The present results provide microscopic insight into the CO oxidation reaction catalyzed by CuMnO_x, which is expected to elucidate the corresponding mechanism and thus guide the design of highly active catalysts.

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