Wenhua Hou

Fabrication of a Novel Glucose Biosensor Based on a Highly Electroactive Polystyrene/ Polyaniline/Au Nanocomposite

A novel nanocomposite with a core-shell structure containing polystyrene (PS), polyaniline (PANI), and Au nanoparticles (NPs) was synthesized. The nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). Cyclic voltammetric experiments indicated that the nanocomposite had excellent redox ability in a wide range of pH values. The existence of Au NPs resulted in a higher electrical conductivity of the nanocomposite. As a model, glucose oxidase (GOD) was entrapped onto the nanocomposite-modified glassy carbon electrode (GCE) and applied to construct a sensor. The immobilized GOD showed a pair of well-defined redox peaks and high catalytic activity for the oxidation of glucose.

Graphene–CdS Nanocomposites: Facile One‐Step Synthesis and Enhanced Photoelectrochemical Cytosensing

Graphene-CdS (GR-CdS) nanocomposites were prepared in a one-step synthesis in aqueous solution. The synthetic approach was simple and fast, and it may be extended for the synthesis of other GR-metal-sulfide nanocomposites. The as-prepared GR-CdS nanocomposite films inherited the excellent electron-transport properties of GR. In addition, the heteronanostructure of the GR-CdS nanocomposites facilitated the spatial separation of the charge carriers, thus resulting in enhanced photocurrent intensity, which makes it a promising candidate for photoelectrochemical applications. This strategy was used for the fabrication of an advanced photoelectrochemical cytosensor, based on these GR-CdS nanocomposites, by using a layer-by-layer assembly process. This photoelectrochemical cytosensor showed a good photoelectronic effect and cell-capture ability, and had a wide linear range and low detection limit for Hela cells. The as-synthesized GR-CdS nanocomposites exhibited obviously enhanced photovoltaic properties, which could be an efficient platform for many other high-performance photovoltaic devices.

Single-crystalline orthorhombic molybdenum oxide nanobelts: synthesis and photocatalytic properties

Single crystalline MoO3 nanobelts with width of 200–300 nm and the length up to several tens of micrometres were prepared by a facile hydrothermal method and characterized. Based on time- and temperature-dependent experiments, a solid–solution–solid transformation mechanism was proposed for the formation of crystalline MoO3 nanobelts. The as-prepared MoO3 nanobelts were used as a photocatalyst to degrade methylene blue (MB) under visible light irradiation and demonstrated a dramatic activity, indicating that the as-prepared MoO3 nanobelts were promising candidates for the photodegradation of organic dyes. A self-sensitization photocatalytic mechanism was suggested based on the experimental results.

EDTA-mediated hydrothermal synthesis of NaEu(MoO4)2 microrugbies with tunable size and enhanced luminescence properties

Tetragonal NaEu(MoO4)2 with rugby-like microstructures were successfully synthesized by a hydrothermal method in an EDTA-mediated process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) techniques were employed to characterize the products in detail. It was found that the amount of EDTA, reaction temperature and pH value are important parameters affecting the morphology, crystallinity and size of the final product, respectively. The possible formation mechanism for the microrugbies was proposed on the basis of a series of time-dependent experiments. This facile method was also successfully applied in the synthesis of NaSm(MoO4)2 and NaGd(MoO4)2 microrugbies. The photoluminescence (PL) properties of NaEu(MoO4)2 microrugbies were strongly dependent on the size and crystallinity. The calcined products displayed excellent luminescence behaviors with a high color purity and have the potential to be applied in LED devices. The possible reasons for the difference in the relative intensities of luminescence are also discussed in detail.

Polyaniline-intercalated layered vanadium oxide nanocomposites--one-pot hydrothermal synthesis and application in lithium battery.

Polyaniline-intercalated layered vanadium oxide nanocomposites were successfully synthesized by an one-pot hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The effects of reaction conditions, such as pH value of the precursor solution, reaction temperature and time, and the amount of aniline on the structure and morphology of the obtained samples, were systematically investigated. Based on the experimental results, an in situ intercalation-polymerization-exfoliation mechanism was put forward for the formation of layered nanocomposites. The application of the resulting layered nanocomposite as the cathode material in lithium battery was tested and the results showed that the polyaniline-intercalated layered vanadium oxide nanocomposite prepared at 140 °C had a good cycling performance and might act as a promising cathode material for high-energy-density rechargeable lithium batteries.

EDTA-mediated shape-selective synthesis of Bi2WO6 hierarchical self-assemblies with high visible-light-driven photocatalytic activities

Bi2WO6 with multilayered disc-like and 3D hierarchical nest-like architectures self-assembled from 2D nanosheets were successfully synthesized by a hydrothermal method in EDTA-mediated processes. It was found that the morphology modulation of the as-obtained products could be easily realized simply by changing the amount of EDTA introduced into the reaction system. The stepwise self-assembly formation mechanisms for two different hierarchical architectures were proposed on the basis of a series of time-dependent experiments. The photocatalytic activities of the different Bi2WO6 samples for the degradation of Rhodamine B (RhB) were also evaluated. Due to the unique morphology, porous structure and large surface area, Bi2WO6 nest-like architectures exhibited better activity performance than Bi2WO6 multilayered microdiscs. The present work not only presents an efficient way for the selectively controllable preparation of Bi2WO6 hierarchical structures viaself-assembly from 2D nanosheets, but also provides a step forward in the design of photocatalysts with controllable morphology and enhanced photocatalytic activities.

Crystalline nanotubes of γ-AlOOH and γ-Al2O3: hydrothermal synthesis, formation mechanism and catalytic performance

Crystalline nanotubes of gamma-AlOOH and gamma-Al(2)O(3) have been synthesized. An anionic surfactant-assisted hydrothermal process yields gamma-AlOOH nanotubes, and appropriate calcination treatment of the gamma-AlOOH nanotubes yields gamma-Al(2)O(3) nanotubes. The nanotubes were characterized by XRD, SEM, TEM, TG-DSC, FTIR and nitrogen adsorption-desorption techniques. Both the gamma-AlOOH and gamma-Al(2)O(3) nanotubes are crystalline, with a representative length of approximately 500 nm and diameters of 20-40 nm. The gamma-Al(2)O(3) nanotubes exhibit a very high mesoporous specific surface area (SSA) of 201.0 m(2) g(-1) and a high mesopore volume of 0.68 cm(3) g(-1) with an average mesopore size of 27.7 nm, as well as a high microporous SSA of 186.0 m(2) g(-1) and a micropore volume of 0.08 cm(3) g(-1) with an average micropore size of 0.53 nm. The formation process was discussed and a possible mechanism was proposed, in which a lamellar phase was first formed by camphorsulfonic anions and Al(III) species, and then rolled up to form the crystalline nanotubes under the hydrothermal condition. The catalytic performance of the obtained gamma- Al(2)O(3) nanotubes was tested by using the dehydration of ethanol to ethylene as a probe reaction and it was shown that the obtained gamma- Al(2)O(3) nanotubes catalyst possesses a higher catalytic activity compared with the gamma- Al(2)O(3) nanoparticles.

Synthesis of functional polypyrrole/ prussian blue and polypyrrole/Ag composite microtubes by using a reactive template

Polypyrrole (PPy)/PB and PPy/Ag composite microtubes were synthesized in one pot by using methyl orange (MO) as a reactive self-degraded template. In contrast to reported conventional template approaches, the MO template did not need to be removed after polymerization. The formation mechanism, structural characteristics, conductivity, and electrochemical properties of the obtained PPy/PB and PPy/Ag microtubes are reported.

One-step synthesis of AgCl/polyaniline core?shell composites with enhanced electroactivity

Silver chloride/polyaniline (PANI) core-shell composites were synthesized through a facile one-step process in the presence of polyvinylpyrrolidone (PVP). PVP not only acted as an anchor agent leading to the formation of the core-shell structure but also prevented the aggregation of PANI efficiently. Transmission electron microscopy (TEM) images gave direct evidence of the core-shell structure. Fourier transform infrared (FTIR) confirmed the formation of PANI and x-ray diffraction (XRD) showed the presence of crystal AgCl. Cyclic voltammetric experiments indicated that this kind of material showed excellent redox ability in neutral solution. Based on the excellent electrochemical behaviour of the AgCl/PANI, it was applied to construct a H(2)O(2) biosensor. The biosensor exhibited a fast amperometric response to H(2)O(2) with the linear range 6 x 10(-4)-9 x 10(-3) mol l(-1).

Synthesis of a graphene/polyaniline/MCM-41 nanocomposite and its application as a supercapacitor

A ternary nanocomposite of graphene/polyaniline (PANI)/porous silica MCM-41 (MCM-41) was prepared by a hydrothermal method. The amount of graphene oxide (GO) in the graphene/PANI/MCM-41 nanocomposite had a strong effect on the supercapacitor performance. The experimental results showed that the specific capacitance of the graphene/PANI/MCM-41 nanocomposite could reach the highest value when the GO content was 50%. The specific capacitance of the nanocomposite was 405 F g−1 at a current density of 0.8 A g−1. Furthermore, over 91.4% of the original capacitance was retained after repeating the galvanostatic charge–discharge for 1000 cycles. The performance of the prepared supercapacitor containing different amounts of GO were studied in detail.