Jie Han

Facile Synthesis of Highly Stable Gold Nanoparticles and Their Unexpected Excellent Catalytic Activity for Suzuki−Miyaura Cross-Coupling Reaction in Water

We have demonstrated that poly(2-aminothiophenol)-stablized gold nanoparticles with proper gold size and polymer thickness are active catalysts for Suzuki-Miyaura cross-coupling reaction of aryl halides with arylboronic acids in water and air for the first time. High yields can be obtained with aryl halides or arylboronic acids bearing a variety of substituents. This new finding will undoubtedly broaden the application of gold nanoparticles in organic catalytic reactions.

Ag-Nanoparticle-Loaded Mesoporous Silica: Spontaneous Formation of Ag Nanoparticles and Mesoporous Silica SBA-15 by a One-Pot Strategy and Their Catalytic Applications

A facile one-step method was proposed for the successful synthesis of Ag-nanoparticle-loaded mesoporous silica SBA-15 composites, where silver ions and their corresponding reductant aniline were added in the traditional synthetic system of mesoporous silica SBA-15 containing P123 as the surfactant and TEOS as the silica source. Mesoporous silica SBA-15 and Ag nanoparticles were spontaneously formed with Ag nanoparticles embedded in channels and even implanted in frameworks of mesoporous silica SBA-15. A tentative formation process was then proposed according to experimental observations. Furthermore, catalytic activities of Ag-nanoparticle-loaded silica SBA-15 composites toward the reduction of 4-nitrophenol in the presence of NaBH(4) and the reduction of H(2)O(2) were also investigated.

Yolk@Shell Nanoarchitecture of Au@r-GO/TiO2 Hybrids as Powerful Visible Light Photocatalysts

Yolk@shell nanostructures of Au@r-GO/TiO2 with mesoporous shells were prepared by a sol-gel coating process sequentially with GO and TiO2 on Au/SiO2 core/shell spheres, followed by calcination and template removal, where the silica interlayer acts as a template not only to produce the void space but also to promote the coating of the r-GO and TiO2 layer. The evaluation of visible light photocatalytic activities in dye decomposition and water-splitting H2 production demonstrated their superior photocatalytic performance, which indicates their potential as powerful photocatalysts.

TiO2/NiO hybrid shells: p–n junction photocatalysts with enhanced activity under visible light

Mesoporous hybrid shells of TiO2/NiO were prepared by sequential coating of TiO2 and NiO on SiO2 nanospheres through a combined sol–gel and hydrothermal process followed by calcination and template removal. Evaluation of visible light photocatalytic activities in dye degradation and H2 production demonstrated their superior performance, which could be attributed to the porous nature of the hybrid shells and the enhanced charge separation and visible-light absorption associated with the introduction of NiO.

Poly(o-phenylenediamine) Submicrosphere-Supported Gold Nanocatalysts: Synthesis, Characterization, and Application in Selective Oxidation of Benzyl Alcohol

A facile solution route was proposed for the successful synthesis of uniform poly(o-phenylenediamine) (PoPD) submicrospheres with an average diameter of 700 nm. Utilizing the reactivity of dedoped PoPD submicrospheres for gold salt HAuCl4, gold nanoparticles can be synthesized in the presence of PoPD without additional reductant for HAuCl4. Furthermore, PoPD submicrospheres with abundant amino groups and pi electrons in benzene rings on their surfaces can significantly stabilize gold nanoparticles, which will lead to the formation of PoPD submicrosphere-supported gold nanoparticles. Reaction conditions, such as addition of poly(vinylpyrrolidone) and concentration of HAuCl4, were found to affect the size of gold nanoparticles. Products were characterized by Fourier-transform infrared (FT-IR) and X-ray diffraction (XRD) spectroscopies. The synthesized PoPD submicrosphere-supported gold nanoparticles with different size were used to evaluate their catalytic performances for benzyl alcohol. Results revealed that PoPD submicrosphere-supported gold nanoparticles showed high yield and selectivity for benzyl alcohol to aldehyde conducted under air and in water media. The factors, such as catalyst size and amount, solvent, temperature, alkali type, and reaction time, were all systematically investigated to elucidate their effects on the yield and selectivity of catalytic benzyl alcohol reactions.

Nanostructured Hybrid Shells of r-GO/AuNP/m-TiO2 as Highly Active Photocatalysts

Nanostructured hybrid shells of r-GO/AuNP/m-TiO2 were synthesized using SiO2 spheres as templates, followed by graphene oxide (GO) and Au nanoparticle (AuNP) deposition and TiO2 coating, and then post-treatments of template removal and calcination. Evaluation of their photocatalytic activity by degradation of Rhodamine B (RhB) under the irradiation of UV, visible light, and simulated daylight demonstrated the superior photocatalytic performance of the sandwich-like hollow hybrid shells, which could be attributed to the porous nature of the hybrid shells and the enhanced charge separation and visible-light absorption of r-GO and AuNPs.

One-pot surfactantless route to polyaniline hollow nanospheres with incontinuous multicavities and application for the removal of lead ions from water.

Polyaniline (PANI) hollow nanospheres with controllable incontinuous nanocavities ranging in size from 10 to 50 nm as a novel hollow nanostructure have been successfully fabricated by chemical polymerization of aniline with chloroaurate acid as the oxidant and citric acid as the doping acid. Experimental factors, such as concentration and kind of oxidant and doping acid, were investigated to illustrate their effect on morphology of PANI. According to experimental results and time-dependent investigations, a possible formation mechanism involved was then proposed. The adaptability of this route to hollow nanostructures with multicavities of other conducting polymer was also revealed. Furthermore, the adsorption properties of PANI hollow nanospheres toward lead ions in water were investigated.

Highly uniform self-assembled conducting polymer/gold fibrous nanocomposites: additive-free controllable synthesis and application as efficient recyclable catalysts.

Uniform poly(2-aminothiophenol) nanofibers embedded with highly dispersed gold nanoparticles have been fabricated through a facile templateless one-step method. The diameter of composite nanofibers can be controlled in the range of 200-80 nm by simply tuning the speed of mechanical stirring during materials synthesis. Results from our work will provide insight into the shape-controlled synthesis of other nanomaterials by simply introducing mechanical agitation. Removal of gold nanoparticles in composite nanofibers leads to polymer nanotubes with continuous or incontinuous nanocavities depending on mechanical stirring speeds. Furthermore, morphology-dependent catalytic performances of such composites are also investigated.

Reactive polyaniline-supported sub-10 nm noble metal nanoparticles protected by a mesoporous silica shell: controllable synthesis and application as efficient recyclable catalysts

Polystyrene@Polyaniline@Au/m-SiO2 yolk/shell nanostructures containing numerous sub-10 nm gold nanoparticles in each particle as highly stable/recyclable polymer-supported gold catalysts have been suggested.

Facile Synthesis of Hierarchical Conducting Polymer Nanotubes Derived from Nanofibers and Their Application for Controlled Drug Release

Hollowing of inorganic nano/micromaterials can be realized by well-known Ostwald ripening and Kirkendall processes. However, hollowing of organic polymer without sacrificial templates is seldom seen. Herein, we demonstrate for the first time that conducting polymer nanofibers can be transformed into nanotubes by a simple, effective, and controllable swelling-evaporation strategy. By controlling swelling degree, surface-patterned poly(o-toluidine) (POT) nanofibers, and nanotubes with controllable inner diameter can be fabricated. Novel characteristics of such nanotubes, such as patterned surfaces and sealed tips, will endow them with enhanced properties when applied in fields as controlled drug delivery, noble metal nanocatalysts supporter, and adsorbent for heavy-metal ions.