Zhengshui Hu

Formation of silver nanoshells on latex spheres

Silver nanoshells on styrene–acrylic acid copolymer latex spheres (PSA) were deposited by an in situ chemical reduction method, ageing a colloid solution at 85 °C containing PSA latex, AgNO3, urotropine, and poly-(vinylpyrrolidone). SEM and TEM observations showed that the silver nanoshells were made of closely packed silver nanoparticles of different sizes and morphologies. UV–visible absorption spectra were recorded to investigate their optical properties.

Imidazoline derivative templated synthesis of broccoli-like Bi2S3 and its electrocatalysis towards the direct electrochemistry of hemoglobin

A broccoli-like bismuth sulfide (bBi2S3) was synthesized via a solvothermal method using a self-made imidazoline derivative of 2-undecyl-1-dithioureido-ethyl-imidazoline as the soft template. The morphology and chemical constitution of the product were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Electrochemical characterization experiments show that the bBi2S3 has the higher specific surface area and standard heterogeneous electron transfer rate constant than the rod-like Bi2S3 (rBi2S3). Hemoglobin (Hb) was then chosen as a protein model to investigate the electrocatalytic property of the synthesized bBi2S3. The results show that Hb entrapped in the composite film of chitosan and bBi2S3 displays an excellent direct electrochemistry, and retains its biocatalytic activity toward the electro-reduction of hydrogen peroxide. The current response in the amperometry shows a linear response to H2O2 concentrations in the range from 0.4 to 4.8µM with high sensitivity (444µAmM(-1)) and low detection limit (0.096µM). The Michaelis-Menten constant (KM(app)) of the fabricated bioelectrode for H2O2 was determined as low as 1µM. These results demonstrate that the synthesized bBi2S3 offers a new path for the immobilization of redox-active protein and the construction of the third-generation biosensors.

Preparation of organic fluids with high loading concentration of Ag2S nanoparticles using the extractant Cyanex 301

Stable organic fluids containing Ag2S nanoparticles modified by Cyanex301 (di-(2,4,4-trimethylpentyl) dithiophosphinic acid) have been prepared directly in alkane via a solvent extraction synthesis method. The organic fluids are so stable that the nanoparticles do not precipitate at room temperature even after more than one year even when the content of Ag2S nanoparticles is as high as 42 g L−1. The Ag2S nanoparticles are characterized by XRD, TEM, IR, UV-vis and TG-DSC, showing that the particles are well modified by the extractant Cyanex301. The obtained nanoparticles can be well dispersed again in organic solvents and the new fluids are also very stable. The loading concentration of Ag2S nanoparticles prepared through the extraction synthesis method is much higher than that prepared via a two-step (preparation and dispersion) synthesis method and found to decrease with an increase of the solvent polarity. The tribological properties of the Ag2S nanoparticles modified by Cyanex301 in liquid paraffin (LP) for a steel–steel friction pair are evaluated on a four-ball machine, showing that such a fluid, LP+Ag2S, has a low friction coefficient.

Preparation of Organic Fluid Containing Ag Nanoparticles with Extractant Cyanex 301

Stable organic fluid containing silver nanoparticles modified by extractant Cyanex 301 (di‐(2, 4, 4‐trimethylpentyl) dithiophosphinic acid) has been prepared directly in alkane by the solvent extraction‐reduction method. Ag+ is extracted into alkane by Cyanex 301, then the obtained Ag+‐Cyanex 301 complex is reduced with solid sodium borohydride to obtain the organic fluids containing Ag nanoparticles. The organic fluids are so stable that the nanoparticles do not precipitate at room temperature for more than two months when the concentration of Ag nanoparticles is about 0.10 mol L−1. The nanoparticles are characterized by XRD, TEM, IR, UV‐Vis, and TG‐DTG, showing that Ag nanoparticles are well modified by the extractant. The obtained Ag nanoparticles can be dispersed well in organic solvent again, and the new fluids are very stable in air. The loading concentrations decrease with increase of solvent polarity.

Tribological properties of Cyanex 301‐modified MoS2 nano‐sized hollow spheres in liquid paraffin

Purpose – The purpose of this paper is to investigate the tribological properties of MoS2 nano‐sized hollow spheres in liquid paraffin (LP) and the corresponding action mechanism. Morever, its feasibity of industrial application as an oil additive in the industrial lubrication field is also explored.Design/methodology/approach – The tribological properties of MoS2 nano‐sized hollow spheres (NH‐MoS2) modified by Cyanex 301(di‐(2,4,4‐trimethylpentyl) dithiophosphinic acid) with size of 200 ∼ 300 nm in LP are studied and compared with those of the commercial colloidal MoS2 (CC‐MoS2) on a four‐ball tester and an Optimol SRV Oscillating friction and wear tester in a ball‐on disk configuration. The worn surfaces of the lower flat disc are examined with a scanning electron microscopy and an X‐ray photoelectron spectroscopy, respectively.Findings – Results show that NH‐MoS2 is a better extreme‐pressure additive and anti‐wear (AW) and friction‐reducing additive in LP than CC‐MoS2. Under the optimum concentration o...

Preparation, Characterization of CeO2-ZrO2 Composite Hollow Microspheres and Their Application as Electrocatalysis Materials for Hemoglobin in Biosensor

Composite hollow microspheres of CeO2-ZrO2 were prepared by using anionic PSA latex particles as template and then calcining the PSA core particles at 600°C. The samples were characterized by XRD, TEM, TG, SEM, EDS, and FT-IR spectra. The effects of the proportion of CeO2 on the structure of the microspheres were also studied. Electrochemical assay showed that the CeO2-ZrO2 composite hollow spheres hydrided with chitosan could be used as a novel biosensing material to detect the direct electron transfer of hemoglobin.

Study on the thiophosphinic extractants. II. Thermodynamic functions and structural parameters of the w/o microemulsion of the saponified acid systems

Abstract Purified sodium salt of Cyanex302, di (2,4,4-trimethylpentyl) monothiophosphinic sodium, NaDTMPTP, and that of Cyanex301, di (2,4,4-trimethylpentyl) dithiophosphinic sodium, NaDTMPDTP, are prepared from the corresponding extractant respectively. The thermodynamic function Δ G o→i 0 (standard Gibbs free energy change of transferring alcohol from oil phase to interface phase) and structural parameters of the sodium salt NaA (0.200 g)–alcohol–diluent–H 2 O microemulsion system are measured. The effects of substitution of oxygen by sulfur in the extractant molecule, the used diluent, alcohol, the temperature and water content V H 2 O on the thermodynamic function and structural parameters are discussed and compared with the corresponding sodium salt of phosphinic acid (purified Cyanex272) system, respectively. The replacement of oxygen atom(s) by sulfur in HA or NaA molecules makes their steric configurations and polarities changed.

Synthesis of Mono-Dispersed Mg(OH)2 Nanoflakelets

Mono-dispersed Mg(OH)2 nanoflakelets have been prepared with the assistant of 4-(p-nitrophenylazo)resorcinol. The samples were characterized using XRD, TEM, and ED. Electron diffraction analysis showed that single crystalline nanoflakelets were obtained in hydrothermal process, and porous Mg(OH)2 nanosheets were prepared at lower temperature. Nitrogen adsorption isotherms show that the surface area of Mg(OH)2 nanosheets is 129 m2/g. Possible growth mechanism of the nanoflakelets is discussed.

Surfactant‐Assisted Synthesis of Cube‐Shaped PbTe and PbSe Nanocrystals

Uniform cubic‐shaped PbTe and PbSe nanocrystals have been synthesized through the surfactant‐assisted hydrothermal reaction between Pb(NO3)2 and Te or Se powders with hydrazine hydrate as reducing reagent. The products were characterized by powder x‐ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that the shapes of nanocubes are well controlled by using ethylenediaminetetraacetic acid as chelating reagent and in the presence of poly(vinyl‐pyrrolidone).

Solvothermal Synthesis and Characterization of Surfactant-Modified CdS Microspheres

CdS crystals with spherical morphology have been prepared by a solvothermal method using a self-made novel block-like imidazoline-gemini surfactant quaternary ammonium salt of di (2-undecyl-1-formyl aminoethyl thiourea imidazoline) hexanediamine (SUDEIHDI) as the shape-controlling agent. The obtained CdS products are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), infrared ray spectroscopy (IR), UV-vis absorption spectroscopy, and x-ray diffraction (XRD), respectively. In addition, the formation mechanism for the CdS sphere was also discussed.