Irradiation of Fe–Mn@SiO2 with microwave energy enhanced its Fenton-like catalytic activity for the degradation of methylene blue

Research on Chemical Intermediates - The application of microwave energy in the synthesis of catalytic materials has been indicated to induce desirable effects that lead to improved activity....     

Pt||ZrO2 nanoelectrode array synthesized through the sol–gel process: evaluation of their sensing capability

Homogeneous, circular Pt||ZrO₂ nanoelectrodes have been synthesized through the sol–gel chemistry and the dip-coating process. These nanoelectrode arrays have been evaluated as a platform for electropolymerization of phenol, as model. We have shown that the microstructure of the polymer depends on the confined environment of the electrode and on the position of the –OH group of the monomer. Additionally, these nanoelectrodes have been tested as an electrochemical sensor for dihydroxybenzene isomers in aqueous medium. These Pt||ZrO ₂ nanoelectrodes exhibit a detection limit of 2?×?10^?7?M for resorcinol and 1?×?10^?6?M for catechol.     

Studies on Chitosan modified ZrO2–CeO2 metal oxide and their Photo catalytic activity under solar light irradiation for water remediation

Chitosan modified CeO₂/ZrO₂ were prepared by co-precipitation method and its photocatalytic activity was studied while exposed to solar light. Various doping concentrations was evaluated and 30 mol % CeO₂/ZrO₂ doping concentration enhanced higher activity when it was modified into Chitosan employing Orange G dye as a model pollutant while exposed to sun light. The synthesized catalyst was highly crystalline, and its average crystalline size was found to be 30 nm using X-ray diffraction analysis. Structural morphology, functional groups, thermal decomposition temperature and particle size were confirmed by Scanning Electron Microscope (SEM), Fourier Transform-Infra Red, Thermal Gravimetric Analysis and Transmission Electron Microscope analysis. XPS confirms the band alignment and oxidation states of the synthesized photo catalyst. In accordance with the UV-Diffused Reflectance Spectrum, the band gap energy is 2.9 eV. The enhanced photo catalytic activities of the prepared photocatalyst were confirmed by effect of catalyst, effect of dye concentration, effect of electrolytes, kinetics and COD. The reaction follows first order kinetics, and the pseudo first order rate constant was evaluated from the kinetics plot.     

Ordered mesoporous Pt/Fe3O4–CeO2 heterostructure gel particles with enhanced catalytic performance for the reduction of 4-nitrophenol

The unique physicochemical properties of ordered mesoporous transition metal oxides have attracted more and more attention. The hydrolysis process of metal oxide precursors is difficult to control, and it is difficult to synthesize an ordered mesoporous transition metal oxide material using the conventional template method. Ordered mesoporous Pt/Fe₃O₄–CeO₂ heterostructure gel materials with excellent catalytic properties were successfully prepared using aerogel technology and the chemical deposition method. The Pt/Fe₃O₄–CeO₂ material was an n–n combined heterostructured semiconductor material which consisted of a magnetic Fe₃O₄ layer, a CeO₂ core and Pt noble metal doped nanoparticles. A layer of Fe₃O₄ thin film was formed on the surface of ordered mesoporous Pt/CeO₂ gel matrix material using the chemical deposition method. The intriguing heterostructural features could facilitate reactant diffusion and exposure of active sites which could enhance synergistic catalytic effects between the Pt nanoparticles and CeO₂ nanoparticles. Compared with Pt/CeO₂, the prepared Pt/Fe₃O₄–CeO₂ showed enhanced catalytic activity in the reduction of 4-nitrophenol at room temperature. The catalytic activity of the heterostructure catalysts was systematically investigated using 4-nitrophenol reduction as a model reaction. The results showed that the Pt (0.1%)/Fe₃O₄–CeO₂ sample exhibited the optimal catalytic performance toward catalytic reduction of 4-nitrophenol to 4-aminophenol. The study provided a method for the preparation of heterostructure nanocatalysts with high efficiency, which would be effective for application in various catalytic reactions.     

Electrochemical immunosensor for the breast cancer marker CA 15–3 based on the catalytic activity of a CuS/reduced graphene oxide nanocomposite towards the electrooxidation of catechol

The authors report on an electrochemical immunosensor for the tumor marker carbohydrate antigen 15–3 (CA15–3). It is based on the use of a composite consisting of reduced graphene oxide (RGO) and copper sulfide (CuS) that was placed on a screen-printed graphite electrode. The electrode shows excellent activity towards the oxidation of catechol acting as an electrochemical probe, best at a working potential of 0.16 V. The electrode was modified with antibody against CA15–3. Once the analyte (CA15–3) binds to the surface of the electrode, the response to catechol is reduced. The assay has a linear response in the 1.0–150 U mL^?1 CA15–3 concentration range, with a 0.3 U mL^?1 lower detection limit and a sensitivity of 1.88 μA μM^?1 cm^?2. The immunosensor also shows good reproducibility (2.7%), stability (95% of the initial values after storing for four weeks). The method was successfully applied to the determination of CA15–3 in serum samples, and results were found to compare well to those obtained by an ELISA. Conceivably, this nanocomposite based detection scheme has a wider scope and may be applied to numerous other immunoassays.

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Graphical abstract A label-free electrochemical immunosensor based on copper sulfides/graphene nanocomposites was developed for enzyme-free determination of CA15–3 biomarker. This immunosensor can be utilized as a tool to detect of CA15–3 in real samples.

     

Pt/TiO2–x nanofibrous aerogel for effective nitrogen reduction: A simple strategy for simultaneous Pt formation and TiO2–x vacancy engineering

Electrocatalysis plays an increasingly important role in converting atmospheric molecules （e.g.,N₂,CO₂and H₂O） to value-added products （e.g.,NH₃,C₂H₄and H₂）.However,developing a simple strategy for preparing catalysts with high performance for the effective conversion of clean energy is still full of challenges.Herein,we describe a straightforward,one-step reduction method to achieve the formation of Pt nanoparticles （N...     

Pt/TiO2–x nanofibrous aerogel for effective nitrogen reduction: A simple strategy for simultaneous Pt formation and TiO2–x vacancy engineering

Electrocatalysis plays an increasingly important role in converting atmospheric molecules （e.g.,N₂,CO₂and H₂O） to value-added products （e.g.,NH₃,C₂H₄and H₂）.However,developing a simple strategy for preparing catalysts with high performance for the effective conversion of clean energy is still full of challenges.Herein,we describe a straightforward,one-step reduction method to achieve the formation of Pt nanoparticles （N...     

Aqueous treatment of single-walled carbon nanotubes for preparation of Pt–Fe core–shell alloy using galvanic exchange reaction: Selective catalytic activity towards oxygen reduction over methanol oxidation

We have demonstrated a new, cost effective synthesis of single-walled carbon nanotube supported Pt–Fe core–shell alloy catalyst (Pt–Fe/SWNT) for the direct methanol fuel cell using galvanic exchange reaction. The Pt–Fe/SWNTs have shown much larger Pt active surface area (150 m²/g-Pt) than the commercial catalyst (54 m²/g-Pt). Furthermore, four-fold enhancement of catalytic activity of the Pt–Fe/SWNTs for oxygen reduction reaction (ORR) has been observed. This catalyst has also demonstrated its tolerance to methanol in ORR.     

Preparation,characterization and catalytic activity of MoO3/CeO2–ZrO2 solid heterogeneous catalyst for the synthesis of β-enaminones

A series of CeO₂–ZrO₂ with different molybdenum (8–20 wt% MoO₃) loaded materials were prepared by homogeneous co-precipitation followed by impregnation method. The prepared materials were tested for their catalytic activity performance in the synthesis of β-enaminones by condensation of various anilines with dimedone under solvent-free conditions in microwave providing excellent yields within short reaction time. An obtained result reveals that, catalytic activity increases with increase in Mo wt% loading. The particle size of prepared materials was estimated using Debye–Scherrer equation. Particle size increases with increase in Mo wt% loading providing nanosized particle ranging from 7.11 to 42.09 nm. The synthesized materials were characterized by means of X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques.     

Insight into the boosted activity of TiO2–CoP composites for hydrogen evolution reaction: Accelerated mass transfer,optimized interfacial water,and promoted intrinsic activity

The use of abundant elements in the earth as electrocatalytic hydrogen production catalysts is of great significance for hydrogen energy cycling. Herein, we report amorphous TiO₂-decorated CoP/NF(TiO₂–CoP/NF) as an excellent electrocatalyst for alkaline hydrogen evolution reaction(HER). The welldispersed amorphous TiO₂on nanoneedle-like CoP arrays preserves the crystal structure of CoP and changes its electronic structure by interfacial charge transfer. Compared ...     

Enhancement of the catalytic performances and lifetime of Ni/γ-Al2O3 catalysts for the steam toluene reforming via the combination of dopants: inspection of Cu,Co, Fe,Mn, and Mo species addition

In this work, the influence of metallic dopant addition in 10 wt % Ni/γ-Al₂O₃ catalyst on the material physico-chemical properties and catalytic activity for the toluene steam reforming was studied. Seventeen doped Ni/γ-Al₂O₃ catalysts were synthesized by the sol–gel process. The aim of this study was to determine which elements were the most suitable for the doping of 10 wt % Ni/γ-Al₂O₃ catalysts. The influence of the dopants was studied through different physico-chemical techniques. It appeared that some dopants showed lower catalytic performances due to high carbon deactivation. On the contrary, some dopants increased the resistance to coking while also improving the catalytic activity. Different mechanisms were proposed to explain these modifications of catalytic behavior. Among all doped Ni/γ-Al₂O₃ catalysts, the samples that combined Mn + Mo or Co + Mo dopants showed the best catalytic performances at 650 °C. Both samples showed high toluene reforming activity and low amounts of carbon deposit.     

Aerobic oxidation of alcohol by model complexes relevant to metal site galactose oxidase: role of copper(I) intermediate,evidence for the generation of end-on copper(II)–OOH species and catalytic promiscuity for oxidation of benzyl alcohol,catechol and o-aminophenol

Transition Metal Chemistry - Tridentate ligands having meridional NNO donor centres were designed and synthesized mimicking the copper coordination in the metal site of galactose oxidase enzyme....     

Development and validation of a sensitive and specific LC–MS/MS cocktail assay for CYP450 enzymes: Application to study the effect of catechin on rat hepatic CYP activity

A sensitive and specific liquid chromatography tandem mass spectrometric (LC–MS/MS) method that enables the simultaneous quantification of probe substrates and metabolites of cytochrome P450 (CYP) enzymes was developed and validated. These substrates (metabolites)—coumarin (7-hydroxycoumarin), tolbutamide (4-hydroxytolbutamide), S-mephenytoin (4-hydroxymephenytoin), dextromethorphan (dextrorphan), and testosterone (6β-hydroxytestosterone)—were utilized as markers for the activities of the major human CYP enzymes CYP2A6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, respectively. Analytes were separated on Kinetex C₁₈ column (2.1 × 50 mm, 5 μm) using a binary gradient mobile phase of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. Metabolites were detected and quantified by MS using multiple reaction monitoring at m/z 163 → 107.2 for 7-hydroxycoumarin, m/z 235 → 150.1 for 4-hydroxymephenytoin, m/z 287 → 171 for 4-hydroxytolbutamide, m/z 258 → 157.1 for dextrorphan, m/z 305 → 269 for 6β-hydroxytestosterone, and m/z 237 → 194 for the internal standard. The assay exhibited good linearity over a range of 10–500 ng/mL with acceptable accuracy and precision criteria. As a proof of concept, the developed cocktail assay was successfully used to examine the potential impact of catechin on the activity of the major rat liver CYP enzymes.     

Half-sandwich η-arene–ruthenium(II) complexes bearing 1-alkyl(benzyl)-imidazo[4,5-f][1,10]-phenanthroline (IP) derivatives: the effect of alkyl chain length of ligands to catalytic activity

The reaction of bromoalkanes (R–Br; (3), R=C_nH_2n+1, n=4 (a), 8 (b), 12 (c),18 (d)) and bromobenzyl derivatives (R′–Br; (4), R′=CH₂C₆H₂(CH₃)₃-2,4,6 (a); CH₂C₆H(CH₃)₄-2,3,5,6 (b); CH₂C₆(CH₃)₅ (c)) with 1H-imidazo[4,5-f][1,10]-phenanthroline (IP)(L₂) gave the corresponding 1-R-imidazo[4,5-f][1,10]-phenanthroline (IPR)(L_3a–d) and 1-R′-imidazo[4,5-f][1,10]-phenanthroline(IPR')(L_4a–c) ligands, respectively. Treatment of L_3a–d and L_4a–d with [Ru(p-cymene)Cl₂]₂ led to the formation of [Ru(p-cymene)(IPR)Cl]Cl (RuL_3a–d) and [Ru(p-cymene)(IPR′)Cl]Cl (RuL_4a–c). New ruthenium(II) complexes RuL_3a–d and RuL_4a–c were characterized by elemental analysis, FTIR, UV–visible and NMR spectroscopy. In order to understand effects of these changes on the N-substituent of imidazol on IP and how they translate to catalytic activity, these new RuL₂, RuL_3a–d and RuL_4a–c were applied in the transfer hydrogenation of ketones by 2-propanol in presence of potassium hydroxide. The activities of the catalysts were monitored by NMR and GC analysis.     

One-pot four-component domino strategy for the synthesis of novel spirooxindole–pyrrolidine/pyrrolizidine-linked 1,2,3-triazole conjugates via stereo- and regioselective [3+2] cycloaddition reactions: In vitro antibacterial and antifungal studies

In this study, a series of highly diversified novel functionalized spirooxindolopyrrolidine and spirooxindolopyrrolizidine-linked 1,2,3-triazole conjugates have been synthesized by a one-pot, four-component condensation of (E)-2-(1-propargyl-2-oxoindoline-3-ylidene)acetophenones as bifunctional dipolarophiles, acenaphthenequinone, α-amino acids with substituted aryl azides using coinage metal catalysts. It was found that CuSO₄/Na ascorbate as a catalyst was more performant than Ag₂CO₃ or CuI. The single-crystal X-ray analysis of one of the cycloadducts proves the structure and the regiochemistry of this reaction. The compounds have been screened for their in vitro antibacterial and antifungal activities using the agar dilution method and display good activities.