PROPERTIES OF HIGHLY DISPERSED PALLADIUM CATALYSTS ON POLY N-VINYL-2-PYRROLIDONE

Four kinds of palladium catalysts dispersed on poly-N-vinyl-2-pyrrolidone were prepared by using CH3OH-NaOH, NaBH4, H2O or CH3OH-H2O as the reducing agent in the process of catalyst preparation. The catalysts were characterized by XPS, TEM, XRD and used for the hydrogenation of methyl acrylate. It was found that the valence state of palladium and distribution of palladium particles as well as the hydrogenation rate were greatly affected by the reducing agent. The best evenly dispersed palladium catalyst showing high hydrogenation activity was prepared using CH3OH-NaOH as the reducing agent.     

A Hydrogen Peroxide Sensor Based on Silver Nanoparticles Biosynthesized by Bacillus subtilis

In this study, silver nanoparticles （AgNPs） were biosynthesized by Bacillus subtilis and used to construct a nonenzymatic hydrogen peroxide （H202） sensor, Scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy confirmed that the AgNPs were prepared successfully with spherical morphol- ogy. The electrochemical properties of the resulted sensor were investigated by cyclic voltammetry, chronoam- perometry and electrochemical impedance spectroscopy. It was found that the sensor exhibited good electrocatalytic activity towards H202 reduction with a wider linear range from 0.05 to 120 mmol.L-1, a detection limit of 8 gmol.L-1 and a fast response time less than 2 s. The sensor exhibited good selectivity for H202 determination in the presence of glucose, acetaminophen, ascorbic acid and uric acid.     

Voltammetric Determination of Epinephrine in the Presence of Uric Acid Based on Aminated Graphene and Ag NPs Hybrid Membrane Modified Electrode

A hybrid membrane consisted of aminated graphene and Ag nanoparticles（Ag NPs） was prepared on the surface of glassy carbon electrode（GCE） by cyclic voltammetry（CV） with aminated graphene（GR-NH2） as matrix for immobilizing Ag NPs.The morphology and electrochemical properties of this hybrid membrane were characterized by scanning electron microscopy（SEM） and CV,respectively,and on this membrane,the voltammetric behaviors of epinephrine（EP） were studied in detail.The membrane exhibited excellent eletro-catalytic activities for the redox of EP,and could resolve the electrochemical response of EP and uric acid（UA） into two oxidation peaks.The peak current of EP was linear with its concentration in the ranges of 0.916-18.3 μmol/L and 18.3-184 μmol/L.The detection limit was 2.0 nmol/L（S/N=3）.The proposed modified electrode retained the advantages of easy fabrication,high sensitivity and good repeatability for the determination of EP.     

Synthesis and Electrochemical Performance of Co3O4/Graphene

Co3O4/reduced graphene oxide composites were synthesized via a simple electrochemical method from graphene oxide and Co（NO3）2·6H2O as raw materials.Co3O4 nanoparticles with sizes of around 30-50 nm were distributed on the surface of graphene nanosheets confirmed by scanning electron microscopy and transmission electron microscopy.Electrochemical properties of Co3O4/graphene composite were tested by cyclic voltammetry,galvanostatic charge-discharge,and electrochemical impedance spectroscopy.The Co3O4/reduced graphene oxide composite was used as the pseudocapacitor electrode in the 2 mol/L NaOH aqueous electrolyte solution.The Co3O4/reduced graphene oxide composite electrode exhibited a specific capacitance of 357 F/g at a current density of 0.5 A/g in a three-electrode system.72％ of capacitance was retained when the current density increased to 3 A/g.The Co3O4/reduced graphene oxide composite prepared electrodes show a high rate capability and excellent long-term stability.After 1000 cycles of charge and discharge,the capacitance is still maintained 87％ at a current density of 1 A/g,indicating that the composite is a oromising alternative electrode material used for supercapacitors.     

Pd/Hβ-zeolite catalysts for catalytic combustion of toluene:Effect of SiO_2/Al_2O_3 ratio

The effect of pure and high silica Hβ zeolites on the catalytic performance of toluene combustion over Pd/Hβ catalyst was evaluated.Pure and high silica β zeolites were prepared by direct synthesis procedures,then 0.1 wt% of palladium was impregnated on different Hβ zeolites via in-cipient wetness technique using palladium nitrate as the Pd source.The Pd/Hβ catalysts were characterized by XRD,N2 adsorption/desorption,H2O adsorption,NH3-TPD,H2-TPR and XPS techniques.With increasing the SiO2/Al2O3 ratio of β zeolite,the activity of the Pd/Hβ catalysts for toluene combustion increased clearly and the pure silica β zeolite supported Pd catalyst showed the best catalytic activity.The superior catalytic performance of Pd/β catalyst prepared from pure silica β zeolite was attributed to its high hydrophobicity and the preserving ability for PdO active species.     

Pd/Hβ-zeolite catalysts for catalytic combustion of toluene: Effect of SiO2/Al2O3 ratio

The effect of pure and high silica Hβ zeolites on the catalytic performance of toluene combustion over Pd/H/3 catalyst was evaluated.Pure and high silica β zeolites were prepared by direct synthesis procedures,then 0.1 wt% of palladium was impregnated on different Hβ zeolites via incipient wetness technique using palladium nitrate as the Pd source.The Pd/Hβ catalysts were characterized by XRD,N2 adsorption/desorption,H2O adsorption,NH3-TPD,H2-TPR and XPS techniques.With increasing the SIO2/Al2O3 ratio of β zeolite,the activity of the Pd/Hβ catalysts for toluene combustion increased clearly and the pure silica β zeolite supported Pd catalyst showed the best catalytic activity.The superior catalytic performance of Pd/β catalyst prepared from pure silica β zeolite was attributed to its high hydrophobicity and the preserving ability for PdO active species.     

Fabrication of the electrochemically reduced graphene oxide-bismuth nanoparticles composite and its analytical application for an anticancer drug gemcitabine

The present study explores an electroreduced graphene oxide-bismuth nanoparticles composite(ErGOBi) as an electrochemical sensor for the determination of an anticancer drug, gemcitabine hydrochloride(GMB). The Er-GOBi interface was prepared by drop casting of bismuth nitrate-graphene oxide suspension on a glassy carbon electrode(GCE) followed by electro-reduction in the potential range of 0.6 V to 1.7 V. SEM, FTIR, EDAX and AFM techniques were employed for the characterization of prepared materials. Cyclic voltammetric and electrochemical impedance spectroscopic methods were used to understand the charge transfer properties of stepwise modification of Er-GOBi/GCE. GMB exhibited an irreversible oxidation peak at 1.144 V on Er-GOBi/GCE in phosphate buffer of p H 3. A 100-fold enhanced oxidation peak current was observed at Er-GOBi/GCE when compared to that at bare GCE.Sensing performance of Er GO-Bi/GCE was optimized by varying peak current dependent parameters.Linear relationship between the peak current and concentration of GMB was observed in the range of 0.1–51.1 mmol/L in differential pulse voltammetric method and 2.1–61.1 mmol/L in linear sweep voltammetric method. The practical utility of the proposed sensor, Er-GOBi/GCE was demonstrated by determining GMB in pharmaceutical formulations and spiked urine samples.     

Construction and application of an electrochemical sensor based on graphene-MXene nanocomposites for baicalin detectionEI北大核心CSCD

Redox graphene-MXene(rGO-MXene) nanocomposites were prepared by ion polymerization and used to construct a highly sensitive electrochemical sensor for baicalin(BA) detection. The synergistic effect of rGO and MXene increased the specific surface area and electron transport capacity of the electrode, and significantly enhanced the electrochemical response of BA. The cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of BA on the sensor. Under the optimal conditions, the peak current exhibited a good linear relationship with BA concentration in the range of 0. 05-10 μmol / L, and the limit of detection was as low as 28 nmol / L. The method was applied to analyze traditional Chinese medicine preparations containing baicalin, such as Qingkailing Capsule and Sanhuang Tablets with good accuracy and spiked recovery. The results were highly consistent with those of high performance liquid chromatography, providing a technical means for the rapid and sensitive detection of traditional Chinese medicine preparations. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Synthesis of ruthenium/reduced graphene oxide composites and application for the selective hydrogenation of halonitroaromatics

Reduced graphene oxide （RGO） supported ruthenium （Ru） catalyst was prepared by an impregnation method using RuCI3 as a precursor and RGO as a support. The catalyst Ru/RGO was used for the selective hydrogenation ofp-chloronitrobenzene （p-CNB） to p-chloroaniline （p-CAN）, showing a selectivity of 96% at complete conversion of p-CNB at 60 ℃ and 3.0 MPa H2. The Ru/RGO catalyst was extremely active for the hydrogenation of a series of nitroarenes, which can be attributed to the small sized and the fine dispersity of the Ru nanoparticles on the RGO sheets characterized by TEM. Moreover, the catalyst also can be recycled five times without the loss of activity.     

Efficient nonenzymatic hydrogen peroxide sensor in acidic media based on Prussian blue nanoparticles-modified poly(o-phenylenediamine)/glassy carbon electrode

The Prussian blue nanoparticles(PBNPs) were prepared by a self-assembly process, on a glassy carbon(GC) electrode modified with a poly(o-phenylenediamine)(Po PD) film. The stepwise fabrication process of PBNPs-modified Po PD/GCE was characterized by scanning electron microscopy(SEM) and electrochemical impedance spectroscopy. The prepared PBNPs showed an average size of 70 nm and a homogeneous distribution on the surface of modified electrodes. The PBNPs/Po PD/GCE showed adequate mechanical, electrochemical stability and good sensitivity in comparison with other PB based H_2O_2 sensors. The present modified electrode exhibited a linear response for H_2O_2 reduction over the concentration range of 1–58.22 mmol L ~(-1)with a detection limit of ca. 0.8 mmol L ~(-1)(S/N = 3), and sensitivity of 3187.89 m A(mol L ~(-1)) ~(-1)cm 2using the amperometric method. This sensor was employed for the H_2O_2 determination in real sample and also exhibited good interference resistance and selectivity.     

POMs as Active Center for Sensitively Electrochemical Detection of Bisphenol A and Acetaminophen

A new type of electrochemical sensor based on multi-walled carbon nanotubes(MWCNTs), K2H4SiW11CuO39-6H2O(SiW11Cu) and gold nanoparticles(AuNPs) was prepared for the simultaneous detection of bisphenol A and acetaminophen. Differential pulse voltammetry(DPV), cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) were used for electrochemical characterization, and Fourier transfonn infrared spectroscopy(FTIR) was used to characterize the structure of polyoxometalates. Electrochemical experimental results show that the composite modified electrodes have good electrochemical activity as well as current response values of bisphenol A and acetaminophen when pH=7.0. At the same time, the modified electrode exhibits good stability and reproduction, and has good anti-interference ability to other substances. In practical application, the sensor obtained satisfactory results.     

Preparation of microcapsule-supported palladium catalyst using SPG (Shirasu Porous Glass) emulsification technique

<正>A new method for the preparation of microcapsule-supported palladium catalyst was described.The highly monodisperse crosslinked polystyrene microcapsules containing phosphine ligand were synthesized by the self-assembling of phase separated polymer (SaPSeP) method using diphenyl(4-vinylphenyl) phosphine and divinylbenzene as a monomer and crosslinking agent,respectively, and 2,2'-azobisisobutyronitrile(AIBN) as an initiator within the droplets of oil-in-water(O/W) emulsions,which were prepared by using the Shirasu Porous Glass(SPG) membrane emulsification technique.The prepared microcapsule-supported palladium catalyst exhibited high catalytic activity for Heck reaction and can be reused several times without loss of activity.     

Detection protein biomarker with gold nanoparticles functionalized hollow mesoporous Prussian blue nanoparticles as electrochemical probes

Gold nanoparticles functionalized hollow mesoporous Prussian blue nanoparticles(Au@HMPB NPs)were synthesized and its peroxidase-like activity was explored for electrochemical probe.The Au@HMPB NPs can reduce H2O2 low detection potential of-0.1 V with high sensitivity.After physically adsorption of antibodies onto the gold nanoparticle surface,the functionalized nanoparticles were turned into immuno-probe.The soluble a-chain of interleukin-2(IL-2)receptor(sCD25)was chosen as a model protein biomarker to test the performance of the probe.sCD25 in the samples were captured and enriched by capture anti-CD25 antibody functionalized magnetic nanospheres.Detection antibody functionalized Au@HMPB can then be linked onto the nanospheres and generate electrochemical current towards H2O2 reduction.The electrochemical responses to 1 mmol/L H2O2 was increased with the increasing concentration of CD25.     

CO oxidation over Co_3O_4/SiO_2 catalysts:Effects of porous structure of silica and catalyst calcination temperature

The catalytic performances of Co3O4/SiO2 catalysts prepared by incipient wetness impregnation for CO oxidation were investigated using three kinds of silica as carriers with different pore sizes of 7.7,14.0 and 27.0 nm.The effects of calcination temperature on the catalyst surface and micro structure properties as well as catalytic performance for the oxidation of carbon monoxide were also studied.All catalysts were characterized by N2 adsorption-desorption,XRD,XPS,FTIR,H2-TPR and O2-TPD.It was found that the properties and crystal size of cobalt-containing species strongly depended on the pore size of silica carrier.While the silica pore size increased from 7.7 to 27.0 nm,the Co3O4 crystal size increased from 8.5 to 13.5 nm.Moreover,it was demonstrated that if the spinel crystal structure of Co3O4 was obtained at a calcination temperature as low as 150℃,the catalyst sample would have a high Co3O4 surface dispersion and an increase of surface active species,and thus exhibit a high activity for the oxidation of carbon monoxide.     

铂沉积对Ga2O3-SiO2纳米粒子光催化性能的提高（英文）

Ga2O3‐SiO2 nanoparticles were prepared by a sol‐gel method and Pt was then immobilized on their surface via photo‐assisted deposition (PAD). The produced samples were characterized using X‐ray diffraction (XRD), ultraviolet and visible spectroscopy, photoluminescence emission spectroscopy, and surface area measurements. The catalytic performances of the Ga2O3‐SiO2 and Pt/ Ga2O3‐SiO2 samples were evaluated for the degradation of cyanide using visible light. XRD and EDX results showed that the Pt was well dispersed within the Ga2O3‐SiO2 phase and was detected on the surface of the catalyst, which confirmed the successful loading of Pt ions by the PAD method. BET results revealed that the surface area of Ga2O3‐SiO2 was higher than that of Pt/Ga2O3‐SiO2 . 0.3 wt% Pt/Ga2O3‐SiO2 exhibited the highest photocatalytic activity for degradation of cyanide under visible light. The catalyst could be reused with no loss in activity for the first 10 cycles.     

A New Amperometric Biosensor Based on HRP/Nano-Au/L-Cysteine/Poly（o-Aminobenzoic acid）-Membrane-Modified Platinum Electrode for the Determination of Hydrogen Peroxide

The third generation amperometric biosensor for the determination of hydrogen peroxide （H2O2） has been described. For the fabrication of biosensor, o-aminobenzoic acid （oABA） was first electropolymerized on the surface of platinum （Pt） electrode as an electrostatic repulsion layer to reject interferences. Horseradish peroxidase （HRP） absorbed by nano-scaled particulate gold （nano-Au） was immobilized on the electrode modified with polymerized o-aminobenzoic acid （poABA） with L-cysteine as a linker to prepare a biosensor for the detection of H2O2. Amperometric detection of H2O2 was realized at a potential of ＋20 mV versus SCE. The resulting biosensor exhibited fast response, excellent reproducibility and sensibility, expanded linear range and low interferences. Temperature and pH dependence and stability of the sensor were investigated. The optimal sensor gave a linear response in the range of 2.99×10^-6 to 3.55×10^-3 mol·L^-1 to H2O2 with a sensibility of 0.0177 A·L^-1·mol^-1 and a detection limit （S/N = 3） of 4.3×10^-7 mol·L^-1. The biosensor demonstrated a 95% response within less than 10 s.     

CO oxidation over Co3O4/SiO2 catalysts: Effects of porous structure of silica and catalyst calcination temperature

The catalytic performances of Co3O4/SiO2 catalysts prepared by incipient wetness impregnation for CO oxidation were investigated using three kinds of silica as carriers with different pore sizes of 7.7, 14.0 and 27.0 nm. The effects of calcination temperature on the catalyst surface and micro structure properties as well as catalytic performance for the oxidation of carbon monoxide were also studied. All catalysts were characterized by N2 adsorption-desorption, XRD, XPS, FTIR, H2-TPR and O2-TPD. It was found that the properties and crystal size of cobalt-containing species strongly depended on the pore size of silica carrier. While the silica pore size increased from 7.7 to 27.0 nm, the Co3O4 crystal size increased from 8.5 to 13.5 nm. Moreover, it was demonstrated that if the spinel crystal structure of Co3O4 was obtained at a calcination temperature as low as 150 ℃, the catalyst sample would have a high Co3O4 surface dispersion and a increase of surface active species, and thus exhibit a high activity for the oxidation of carbon monoxide.     

Carbon black supported ultra-high loading silver nanoparticle catalyst for electro-oxidation and determination of hydrazine

Carbon black supported ultra-high loading silver nanoparticle catalyst (Ag/CB) was prepared by a modified ethylene glycol reduction method, using ethylene glycol as the reducing agent and sodium hydroxide as the pH adjusting agent. The X-ray diffraction, thermogravimetry and scanning electron microscopy characterizations showed that the Ag nanoparticles crystallized with a face-centered cubic structure and were densely stacked on the CB surface without aggregation, despite such a small average size (ca. 10 nm) and an ultra-high loading mass (392 wt.%). The electrochemical evaluation based on cyclic voltammetry, chronoamperometry and polarization tests revealed that the ultra-high loading Ag/CB catalyst possessed a superior electrocatalytic activity for the oxidation of hydrazine, via a diffusion-limited process and a 4-electron transfer pathway. Moreover, the chronoamperometry response on an electrode modified with this ultra-high loading Ag/CB catalyst exhibited a promising application for determination of hydrazine, due to a broad linear calibration ranging from 50 to 800 μM, a high sensitivity of 0.03795 A/ M and a low detection limit of 3.47 μM.     

VINYLATION OF ARYL IODIDES CATALYZED BY〔POLY(STYRYL)BIPYRIDINE〕PALLADIUM(0)

[Poly(styryl)bipyridine]palladium(O),a polymer-bound hydrogrnation catalyst,was characterized by DRS,ESCA and electron microscopy.This material was used as cata-lyst for the vinylation of ary liodides.It was found that the catalytic activlty is comparableto that of the homogeneous catalyst and is not remarkably lowered on being used threetimes With this catalyst,a series of substituted stilbenes,cinnamic acids and methylcinnamates was prepared in high yields.     

Suzuki Reaction of Aryl Bromides Using a Phosphine-Free Magnetic Nanoparticle-Supported Palladium Catalyst

A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g. The catalyst was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared, atomic absorption spectrophotometry, and nitrogen adsorption. The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl bromides with phenylboronic acid. The recovery of catalyst was simply by magnetic decantation in the presence of a magnet. The immobilized palladium catalyst can be reused many times without significant degradation in catalytic activity. No leaching of active palladium species into the reaction solution was detected.