Replication of SMSI via ALD: TiO<Subscript>2</Subscript> Overcoats Increase Pt-Catalyzed Acrolein Hydrogenation Selectivity

The effects of sub-nanometer atomic layer deposition films of titania and alumina are compared for the acrolein hydrogenation selectivity of Pt/SrTiO₃ catalysts. The titania-overcoated catalyst is similar to strong metal-support interaction catalysts formed by high temperature reduction, with a thin titania film on top of the supported Pt nanoparticles and an increase in allyl alcohol selectivity, neither of which are observed for the alumina-overcoated catalyst.

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A Comparative Study of the Photoconduction,Photocatalytic and Electrocatalytic Performance of g-C<Subscript>3</Subscript>N<Subscript>4</Subscript>/ZnS/CuS Heterojunctions with Different Morphologies

Ternary heterojunctions g-C₃N₄/ZnS/CuS with different morphologies were constructed. The g-C₃N₄/ZnS/CuS (hexagonal-nanosheets) exhibited the largest photocurrent, the best photocatalytic and electrochemical activity, which revealed the influence discipline of different morphologies on photoconductivity, photo/electro-catalytic activity. It indicated that this heterojunction can be used as an excellent photoconductor device, a high-efficiency photo/electro-catalyst.

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Zr-Modified SBA-15 Supported Ni Catalysts with Excellent Catalytic Performance of CO Selective Methanation in H<Subscript>2</Subscript>-Rich Fuels

CO selective methanation is a promising route for the purification of CO in H₂-rich gas for on-board H₂-based fuel cells. Herein, we synthesized a Zr-modified SBA-15 supported Ni catalyst, which exhibits both high catalytic performance, deep-removing CO concentration to below 10 ppm with a selectivity higher than 50% in a very low-temperature range (170–220 °C), and long-term stability. The results of XRD, XPS, TPR, TPD and TEM characterizations reveal that the doping of Zr not only improves the dispersion of Ni species, enhances the CO adsorption, but also suppresses the CO₂ adsorption, resulting in the prominent catalytic performance.

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[Zn(<Emphasis Type="SmallCaps">l</Emphasis>-proline)<Subscript>2</Subscript>] Catalyzed One-Pot Synthesis of Propargylamines Under Solvent-Free Conditions

A simple, one-pot, three-component, green synthesis of a wide range of propargylamines is reported by A³-coupling (aldehyde, alkyne and amine) via C–H activation of alkynes using [Zn(l-proline)₂] as an efficient and reusable heterogeneous catalyst. High catalytic activity was achieved in comparatively low temperature under solvent-free conditions. All reactions were carried out in an open atmosphere without the use of any co-catalyst/additive.

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Gold Nanoparticles-Decorated Dithiocarbamate Nanocomposite: An Efficient Heterogeneous Catalyst for the Green A<Superscript>3</Superscript>-Coupling Synthesis of Propargylamines

Gold nanoparticles decorated magnetic dithiocarbamate nanocomposite (Au@CS₂–AP@Fe₃O₄) led to a suitable catalyst for the propargylamines synthesis via A³-coupling reaction in water. The prepared catalyst was characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, atomic absorption spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy measurements.

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Embedding Noble-Metal-Free Ni<Subscript>2</Subscript>P Cocatalyst on g-C<Subscript>3</Subscript>N<Subscript>4</Subscript> for Enhanced Photocatalytic H<Subscript>2</Subscript> Evolution in Water Under Visible Light

Photocatalytic hydrogen evolution is considered as one of the promising pathways to settle the energy crises and environmental issues by utilizing solar energy. In this paper, noble-metal-free Ni₂P was used as cocatalyst to enhance g-C₃N₄ for photocatalytic hydrogen production under visible light irradiation (λ?>?420 nm). Characterization results indicated that Ni₂P nanoparticles were successfully loaded onto g-C₃N₄, which can significantly contribute to accelerate the separation and transfer of photogenerated electron. The hydrogen evolution rate reached ～?270 µmol h^?1 g^?1 and the apparent quantum yield (AQY) was ～?2.85% at 420 nm. Meanwhile, there is no obviously decrease of the hydrogen production rate even after 36 h under visible light illumination. In addition, the mechanism of photocatalytic hydrogen evolution was also elaborated in detail.

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Reaction Profiles of High Silica MOR Zeolite Catalyzed Friedel–Crafts Acylation of Anisole Using Acetic Anhydride in Acetic Acid

Friedel–Crafts reaction of anisole over high silica mordenite zeolite was investigated. Detailed reaction profiles were obtained using various reaction conditions. In particular, the behavior of acetic anhydride during the reaction and the effect on the hydrophilicity of the mordenite zeolite catalyst were investigated.

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Preparation and Characterization of an Efficient Nano-Inorganic Composite of CuO/ZnO/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> for the Catalytic Amination of Aryl Halides in Aqueous Conditions

In this research, an efficient recyclable nano-inorganic composite of CuO/ZnO/Al₂O₃ (CuO/ZnO/Al₂O₃ nanocatalyst) is prepared, characterized and used for the amination of aryl halides with aqueous ammonia in water. The catalyst was prepared by co-precipitation method and characterized by various techniques such as the X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy, and brunauer–Emmett–Teller surface area analysis. Various aryl halides reacted with aqueous ammonia and corresponding products were obtained in high yields. CuO/ZnO/Al₂O₃ nanocatalyst as an efficient stable catalyst is recyclable up to five consecutive runs by simple filtration.

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An efficient recyclable nano-inorganic composite of CuO/ZnO/Al₂O₃ (CuO/ZnO-Al₂O₃ nanocatalyst) is prepared, characterized and used for the amination of aryl halides with aqueous ammonia in water.

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Theoretical and Experimental Studies of CoGa Catalysts for the Hydrogenation of CO<Subscript>2</Subscript> to Methanol

Methanol is an important chemical compound which is used both as a fuel and as a platform molecule in chemical production. Synthesizing methanol, as well as dimethyl ether, directly from carbon dioxide and hydrogen produced using renewable electricity would be a major step forward in enabling an environmentally sustainable economy. We utilize density functional theory combined with microkinetic modeling to understand the methanol synthesis reaction mechanism on a model CoGa catalyst. A series of catalysts with varying Ga content are synthesized and experimentally tested for catalytic performance. The performance of these catalysts is sensitive to the Co:Ga ratio, whereby increased Ga content results in increased methanol and dimethyl ether selectivity and increased Co content results in increased selectivity towards methane. We find that the most active catalysts have up to 95% CO-free selectivity towards methanol and dimethyl ether during CO₂ hydrogenation and are comparable in performance to a commercial CuZn catalyst. Using in situ DRIFTS we experimentally verify the presence of a surface formate intermediate during CO₂ hydrogenation in support of our theoretical calculations.

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Product Selectivity as a Function of ZrO<Subscript>2</Subscript> Phase in Cu/ZrO<Subscript>2</Subscript> Catalysts in the Conversion of Cyclohexanol

The influence of ZrO₂ phase on the product selectivity arising from the preparation method of Cu/ZrO₂ is studied in the gas phase conversion of cyclohexanol. This study results are supported by NH₃-TPD, XRD, pyridine-FTIR and N₂O pulse chemisorptions measurements. However, N₂O pulse chemisorptions studies did not reveal significant differences between the two catalysts. The product selectivity is completely dependent on the ZrO₂ phase which ultimately led to the differences in the acidic properties observed through NH₃-TPD and pyridine-FTIR experiments. Catalyst poisoning experiments using NH₃ co-feeding brought a reversal in the product selectivity.

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Cu/ZrO₂ catalyst prepared by impregnation method containing monoclinic ZrO₂ yields cyclohexanone and Cu/ZrO₂ catalyst prepared by coprecipitation method with tetragonal ZrO₂ phase possessing strong acidic sites yields benzene when cyclohexanol is contacted in vapour phase conditions

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Influence of Tetraalkylammonium Compounds on Photocatalytic and Physical Properties of TiO<Subscript>2</Subscript>

A wide range of experimental data are reported for the first time on the TiO₂ prepared by hydrolysis of highly concentrated Ti(OⁱPr)₄ in water solutions of quaternary ammonium compounds (QACs). These TiO₂ materials have been shown to be photocatalytically active under visible light irradiation (LED, 450 nm) using acetone as a model substrate oxidized in the gas phase. Five-fold increase in activity in comparison with the commercial photocatalyst KRONOClean 7000 is achieved. Colloidal solutions of hydrolyzed Ti(OⁱPr)₄ have been studied by SAXS method suggesting the way in which QACs solutions may influence the final composition of TiO₂. Phase composition, morphology, texture and surface properties of the modified TiO₂ have been studied using XRD, BET, SEM and low-temperature FTIR with CO probe. The surface elemental composition has been investigated by XPS method. Additional low-energy levels and high concentration of acid surface sites originated from N/C-doping, are likely to be the main reasons for exceptional photocatalytic performance of these samples.

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Electrocatalytic H<Subscript>2</Subscript> Evolution of Bis(3,5-di-methylpyrazol-1-yl)acetate Anchored Hexa-coordinated Co(II) Derivative

A mononuclear Co(II) derivative, (1) is afforded by employing a ‘scorpionate’ type precursor, bdtbpza [bdtbpza?=?bis(3,5-di-t-butylpyrazol-1-yl)acetate]. Single crystal X-ray structure reveals that the Co^II ion exhibits an octahedral geometry possessing on a O₆ coordination environment. Detailed EPR interpretation and electrocatalytic hydrogen evolution study are reported. Electrochemical and catalytic study of 1 in DMSO with the presence of acetic acid as weak proton source shows an observed rate constant of 3.7?×?10³ s^?1 and hydrogen evolution Faradaic efficiency of 74.7%. The catalytic process requires two-electron reduction of the catalyst and formation of a cobalt(II)-hydride species as reactive intermediate.

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Morphology-Controlled Synthesis of Co<Subscript>3</Subscript>O<Subscript>4</Subscript> Materials and its Electrochemical Catalytic Properties Towards Oxygen Evolution Reaction

In the present study, we present a facile strategy to synthesis Co₃O₄ materials with different morphology. Experimental results show that Co₃O₄ materials with flower-like, fiber, sheet-like and rod morphologies have been successfully prepared by hydrothermal synthesis in different solvent. The effect of the morphology on the electrochemical catalytic properties were also studied. It is found that sheet-like Co₃O₄ exhibits the best activity towards oxygen evolution reaction (η₁₀?=?390 mV) in 1 M KOH, which can be attribute to its short electrolyte infiltration diffusion path lengths and low charge transfer resistant.

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LSV curves measured at 5 mV/s in 1 M KOH solution for OER, the inset image is FE-SEM image of prepared Co₃O₄ materials. a Flower, b fiber, c sheet and d rod.

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Increased Dispersion of Nickel Particles Supported on Activated Carbon by Treating with Methyl Iodide

A novel method dispersing nickel in fine particles on activated carbon (AC) was proposed in this study. The nickel particles with 2.2 nm average diameter supported on AC were obtained through re-dispersing the nickel particles by treating with methyl iodide under atmospheric pressure. High dispersion of nickel particles promoted the activity for methanol vapor-phase carbonylation over Ni/AC catalyst.

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Hen Egg White Lysozyme Catalyzed Efficient Synthesis of 3-Indolyl-3-hydroxy Oxindole in Aqueous Ethanol

A green synthesis of 3-indolyl-3-hydroxy oxindoles was reported using hen egg white lysozyme (HEWL) in an aqueous ethanol. The HEWL promotes this reaction efficiently from various isatins and indoles under mild reaction conditions with yields up to 98% bearing good adaptability to varied substrates in the reaction. This conversion has provided a new strategy to synthesize 3-indolyl-3-hydroxy oxindole derivatives employing biocatalytic promiscuity of less explored lysozyme. Based on the experimental studies, the plausible reaction mechanism is proposed.

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Biomimetic Cleavage of Aryl–Nitrogen Bonds in <Emphasis Type="Italic">N</Emphasis>-Arylazoles Catalyzed by Metalloporphyrins

The cleavage of C–N single bonds of N-containing compounds provides either an excellent nitrogen source or an excellent carbon source. In this study, an efficient metalloporphyrins/H₂O₂ cleavage of C–N bonds of arylpyrazoles was investigated. The effects of different factors, including different catalysts, catalyst dosages, H₂O₂ dosages, reaction temperature and reaction time were studied. The experimental results showed that the optimal catalyst was FeTPPCl, and the yield of pyrazole derivatives could reach up to 12.3%, which was fourfold higher than hemin catalyzed reaction and closed to ceric ammonium nitrate catalyzed reaction, respectively. Compared with transition-metal-catalyzed and strong-oxidization cleavage of C–N bonds, this protocol is characterized by environmentally-friendly, stable, mild reaction conditions and simplified operation procedures.

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Early Transition Metal Doped Tungstite as an Effective Catalyst for Glucose Upgrading to 5-Hydroxymethylfurfural

Glucose valorization to 5-hydroxymethylfurfural (HMF) remains challenging in the transition towards renewable chemistry. Lewis acidic tungstite is a viable, moderately active catalyst for glucose dehydration to HMF. Literature reports a multistep mechanism involving Lewis acid catalyzed isomerization to fructose, which is then dehydrated to HMF by Brønsted acid sites. Doping tungstite with titanium and niobium improves activity by optimizing the ratio between Lewis and Brønsted acid sites.

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Synthesized Hollow TiO<Subscript>2</Subscript>@g-C<Subscript>3</Subscript>N<Subscript>4</Subscript> Composites for Carbon dioxide Reduction Under Visible Light

The hollow TiO₂@g-C₃N₄ composites were synthesized by a facile stirring method. The phase compositions, optical properties, and morphologies of the samples were characterized via X-ray diffraction, scanning electron microscope, transmission electron microscopy, high resolution transmission electron microscopy, fourier transform infrared spectroscopy, N₂ adsorption–desorption, UV–Vis diffuse reflectance spectroscopy and Photoluminescence. The photocatalyitc performance was evaluated by reduction carbon dioxide under visible light irradiation. The results indicated that TiO₂@g-C₃N₄ nanocomposites displayed higher photocatalytic activity compared with pure g-C₃N₄. The increased photocatalytic activity of TiO₂@g-C₃N₄ nanocomposites can be attributed to facilitating the photo-induced electron–hole separation efficiency and enhancing the photo-induced electron migration.

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β-Cyclodextrin Based Nanosponge as a Biodegradable Porous Three-Dimensional Nanocatalyst in the One-Pot Synthesis of N- Containing Organic Scaffolds

The motivation behind the present study was to develop an application of β-cyclodextrin-based nanosponges with the tiny mesh-like structure as porous three-dimensional nanocatalyst in the one-pot three component condensations of various aromatic aldehydes with activated methylene compounds such as dimedone, thiobarbituric acid, 4-hydroxycoumarin, 4-hydroxy-6-methyl-2-pyrone and nucleophiles including indole and amines. This nanosponge catalyst afforded the privileged N- containing organic scaffolds as key intermediates in pharmaceutical chemistry in very short reaction times.

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PhI-Catalyzed Intramolecular Oxidative Coupling Toward Synthesis of 2-Amino-1,3,4-Thiadizoles

A highly efficient method for the synthesis of thiadiazole derivatives via intramolecular oxidative coupling of thiosemicarbazide, using the in situ generated hypervalent iodine(III) reagents is developed. The protocol can be carried out smoothly and provides a variety of thiadiazole derivatives in moderate to excellent yields.

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A highly efficient method for the synthesis of thiadiazole derivatives via PhI-catalyzed intramolecular oxidative coupling of thiosemicarbazide has been developed.

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