Guangjin Zhang

WO3 nanorods/graphene nanocomposites for high-efficiency visible-light-driven photocatalysis and NO2 gas sensing

One-dimensional (1-D) nanostructures are of great importance due to their superior charge transport properties. Anchoring 1-D semiconductor nanomaterials on graphene offers potential advantages in photoelectrochemical and sensing applications. This paper presents a systematic investigation on the incorporation of WO3 nanorods and graphene for high-efficiency visible-light-driven photocatalysis and NO2 gas sensing. This novel composite shows remarkably enhanced performance compared to pure WO3 nanorods for these applications. The high photocatalytic activity of the WO3/graphene nanocomposite is found to be related to the increased adsorption toward chemical species, enhanced light absorption and efficient charge separation and transfer. Meanwhile, the improved conductivity, specific electron transfer and increased gas adsorption also contribute to their superior sensitivity and selectivity to NO2 gas.

Facile Synthesis of Au-Nanoparticle/Polyoxometalate/Graphene Tricomponent Nanohybrids: An Enzyme-Free Electrochemical Biosensor for Hydrogen Peroxide

A green, facile, one-pot synthesis of well-defined Au NPs@POM-GNSs tricomponent nanohybrids is reported (POM stands for polyoxometalate and GNSs for graphene nanosheets). The synthesis is convenient, rapid and environmentally friendly. The POMs serve as both reducing, encapsulating molecules, and bridging molecules; this avoids the introduction of other organic toxic molecules. Characterization using transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy analysis is performed, and the structure of the prepared nanohybrids of Au NPs@POM-GNSs is verified. Most importantly, the amperometric measurements show the Au NPs@POM-GNSs nanohybrids have high catalytic activity with good sensitivity, good long-term stability, wide linear range, low detection limit, and fast response towards H(2)O(2) detection for application as an enzyme-free biosensor. Transformation of the POMs during H(2)O(2) detection does not affect the catalytic activities of the nanohybrids. Thus, the synergistic effect of Au NPs and GNSs in the nanohybrids leads to the enhanced catalytic property.

Supramolecular Self-Assembly of Amphiphiles on Carbon Nanotubes: A Versatile Strategy for the Construction of CNT/Metal Nanohybrids, Application to Electrocatalysis

Homogeneous coating of carbon nanotubes with metallic nanoparticles was achieved using supramolecular auto-organization of amphiphilic molecules as template. The resulting Pd nanoparticles/carbon nanotube nanohybrids were then evaluated in electrocatalysis experiments, showing superior activity in ethanol oxidation compared to analogous systems.

Bottom-up construction of triazine-based frameworks as metal-free electrocatalysts for oxygen reduction reaction.

A bottom-up method is used to construct novel metal-free catalysts for deeper study of oxygen reduction reaction (ORR) catalysis. Through controlling the structural evolution of a 2D covalent triazine-based framework, the conductivity, nitrogen configurations, and multidoping structures of the as-prepared catalysts can be easily tuned, which makes a great platform for both studying the mechanisms of the ORR and optimizing the performances of the metal-free catalysts.

Molecular Interactions between Wells-Dawson Type Polyoxometalates and Human Serum Albumin

Binding human serum albumin (HSA) of three polyoxometalates (POMs) with the Wells-Dawson structure, alpha(2)-[P2W17O61]10- (abbreviated as alpha(2)-P2W17) and two of its metal-substituted derivatives, alpha(2)-[NiP2W17O61]8- and alpha(2)-[CuP2W17O61]8- (alpha(2)-P2W17Ni and alpha(2)-P2W17Cu, respectively) was studied in an aqueous medium at pH 7.5. Fluorescence quenching, circular dichroism (CD), thermal denaturation, and isothermal titration calorimetry (ITC) were used for this purpose. The results were compared with those obtained previously with the Keggin structure POM, [H2W12O40]6- (H2W12), and the wheel-shaped structure, [NaP5W30O110]14- (P5W30). All these POMs bind HSA mainly by electrostatic interactions. Comparison of the physical characteristics and HSA interaction parameters for the POMs of the present work and those studied previously showed that the overall charge of the clusters is not the single parameter governing the binding process and its consequences. In contrast, besides the influences of the structure, the dimension and/or weight of the POMs, the results have permitted highlighting of the importance of each POM atomic composition for its binding behavior.

CdS nanorods/reduced graphene oxide nanocomposites for photocatalysis and electrochemical sensing

CdS nanorods/reduced graphene oxide (RGO) composites were fabricated through a facile one-pot hydrothermal synthesis. The sample CdS/RGO-1% possesses excellent photocatalytic properties under visible light for the degradation of methyl orange with a rate constant of 1.76 × 10−2 min−1, which is about three times higher than that of pure CdS nanorods. The novel composite material can also be used as an enzyme-free biosensor for H2O2 based on its electrocatalytic behaviour. The low-cost sensor shows rapid response and high sensitivity. This method opens up a facile route for preparing graphene-based nanocomposites with excellent photocatalytic and electrocatalytic properties.

Green chemical decoration of multiwalled carbon nanotubes with polyoxometalate-encapsulated gold nanoparticles: visible light photocatalytic activities

A green, facile, one-pot synthesis of well-defined Au NPs@POM-CNTs tri-component nanohybrids is reported in this paper. The synthesis is convenient, rapid and environmentally friendly. The POMs serve as both reducing, encapsulating molecules and bridging molecules, and avoid introducing other organic toxic molecules. Most importantly, the prepared nanohybrids have been found to have enhanced photocatalytic activities under visible light irradiation. The synergistic effect of the three components in the nanohybrids leads to the enhanced photocatalytic property.

Facile synthesis of a Ag nanoparticle/polyoxometalate/carbon nanotube tri-component hybrid and its activity in the electrocatalysis of oxygen reduction

The facile, one-pot synthesis of Ag nanoparticle-decorated carbon nanotubes (CNTs) is reported. Polyoxometalates (POMs) were used to serve as both reducing and bridging molecules, which avoids the step of introducing other organic toxic molecules. Characterization using transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) analysis, etc. was performed and the structure of the prepared nanohybrid of Ag NPs@POM-CNTs was verified. The nanohybrid showed a high electrocatalytic activity towards oxygen reduction reaction because of the synergistic effect of Ag NPs and CNTs. The POM is removable in the nanohybrid without affecting the catalytic activities.

A general green strategy for fabricating metal nanoparticles/polyoxometalate/graphene tri-component nanohybrids: enhanced electrocatalytic properties

The well-defined metal NPs@POM–GNS tri-component nanohybrids were synthesized by a green, facile, one-pot method. The obtained nanohybrids exhibited exciting electrocatalytic activity for methanol and formic acid oxidation.

Polyoxometalate-mediated green synthesis of a 2D silver nanonet/graphene nanohybrid as a synergistic catalyst for the oxygen reduction reaction

A polyoxometalate (POM)-mediated green, facile and large-scale synthesis of 2D (2-dimensional) Ag NN/GNS nanohybrids (where NN stands for the nanonet and GNSs for graphene nanosheets) is reported. The synthesis is convenient, rapid and environmentally friendly. The POMs serve as reducing, encapsulating and bridging molecules, and avoid introducing any organic toxic molecules. The nanohybrids have been thoroughly characterized using SEM, EDX TEM, XRD, XPS and Raman spectroscopy. Most importantly, the nanohybrids were demonstrated to act as low cost catalysts for the oxygen reduction reaction in fuel cells with similar performance to Pt catalysts. We attribute it to the high catalytic activity of the Ag NN and the excellent electron transfer properties of GNSs and also their synergistic effect, being reinforced by the presence of molybdenum species on the Ag NN/GNS surface.