Xiangke Guo

Sandwich-like LiFePO4/graphene hybrid nanosheets: in situ catalytic graphitization and their high-rate performance for lithium ion batteries

We report a novel approach to fabricate sandwich-like LiFePO4/graphene hybrid nanosheets as battery materials by means of in situ graphitizing organic interlayers (ISGOI). These sandwich-like LiFePO4/graphene nanosheets demonstrated high rate storage and excellent cycle stability.

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.

Expeditious fabrication of flower-like hierarchical mesoporous carbon superstructures as supercapacitor electrode materials

We report a facile and efficient strategy for preparing flower-like hierarchical mesoporous carbon superstructures (FMCS) through a one-pot hydrothermal reaction of nickel acetate with glucose. In the fabrication process of FMCS, the nickel acetate ingeniously plays multifunctional roles: as inducer of flower-like hierarchical carbon, as catalyst of graphitization, and as pore-forming agent. First, flower-like Ni(OH)2/polysaccharide microspheres were self-assembled via a hydrothermal reaction at 180 °C for 24 h. Second, flower-like mesoporous carbon superstructures were obtained by etching and removing the Ni from the Ni/C precursor carbonized from the Ni(OH)2/polysaccharide microspheres. The obtained flower-like superstructures are composed of two-dimensional mesoporous carbon petal building blocks, with a thickness of 20 nm. Electrochemical data showed that the product FMCS-1 displayed a specific capacitance of 226 F g−1 at 0.5 A g−1, and retained 82% (185 F g−1) at a high current density of 20 A g−1, indicative of outstanding rate capability. Furthermore, the three-dimensional (3D) flower-like hierarchical mesoporous carbon superstructures demonstrated excellent cycling stability, with approximately 100% retention of the initial specific capacitance after 2000 cycles at a current density of 10 A g−1.

Organoamine-assisted biomimetic synthesis of faceted hexagonal hydroxyapatite nanotubes with prominent stimulation activity for osteoblast proliferation

Uniform single-crystalline hydroxyapatite nanotubes with hexagonal facets are synthesized via a distinctive organoamines-assisted biomimetic route. These novel HA nanotubes exhibit exceptional performance in stimulating osteoblast proliferation, which gives them intriguing potential for bone repair.

High performance mesoporous zirconium phosphate for dehydration of xylose to furfural in aqueous-phase

The conversion of sugars to chemicals in aqueous-phase is especially important for the utilization of biomass. In current work, zirconium phosphate obtained by hydrothermal methods using organic amines as templates has been examined as a solid catalyst for the dehydration reaction of xylose to furfural in aqueous-phase. The use of dodecylamine and hexadecylamine in the synthesis process results in mesoporous zirconium phosphate with uniform pore width of ∼2 nm and in morphology of nanoaggregates, which is characterized by powder X-ray diffraction, N2 isothermal sorption, NH3 temperature-programmed desorption, FT-IR, and 31P MAS NMR spectroscopy. When used as a catalyst for xylose dehydration to furfural in aqueous-phase, the mesoporous zirconium phosphate presents excellent catalytic performance with high conversions up to 96% and high furfural yields up to 52% in a short time of reaction. Moreover, the catalyst is easily regenerated by thermal treatment in air and shows quite stable activity. The open structure with numerous active sites of the Bronsted/Lewis acid sites is responsible for the high catalytic efficiency of mesoporous zirconium phosphate.

Inorganic nanotubes formation through the synergic evolution of dynamic templates and metallophosphates: from vesicles to nanotubes

A novel synergic evolution of dynamic assembly, from vesicles to nanotubes, between the metallophosphates and organic amines, is disclosed, by which the multicomponent metallophosphate (Cu(2)(OH)PO(4)) nanotubes are synthesized for the first time.

Fabrication of TiO2@carbon core–shell nanosheets for advanced lithium-ion batteries with excellent cyclability

TiO2@carbon with a nanosheet morphology and core–shell structure was constructed by self-assembly/carbonization of P123, CTAB and exfoliated titanate nanosheets. The obtained composite possesses an ultrathin structure (∼5.5 nm) and exhibits high capacity (549 mA h g−1) and excellent cyclability (385 mA h g−1 after 2000 cycles at 4.6 A g−1) as an anode for Li-ion batteries.

Preparation and catalytic property of a non-crystalline alloy of iron–boron with one-dimensional nanostructures

This paper describes our recent progress on the synthesis and catalytic hydrogenation property of iron?boron non-crystalline alloy with one-dimensional nanostructures, including nanowires, nanorods and nanotubes. The synthesis of one-dimensional nanostructures of iron?boron non-crystalline alloy involves the use of lyotropic liquid crystals of non-ionic?anionic mixed surfactants as templates. The non-ionic surfactants used are Tween 40 (polyoxyethylene sorbitan monopalmitate) and Tween 60 (polyoxyethylene sorbitan monostearate), and the anionic surfactant is CSA (camphorsulfonic acid). The non-crystalline iron?boron nanotubes thus prepared are more effective than the corresponding nanowires and nanorods for the catalytic hydrogenation of m-nitrotoluene. The lyotropic liquid crystals of mixed surfactants provide an effective template for the fabrication of inorganic materials with one-dimensional nanostructures.

Biomimetic synthesis of aluminophosphate nanorolls induced by mixed organoamines

Natural kingite-like aluminophosphate nanorolls were obtained by biomimetic synthesis using a mixed-organoamine template.

Fabrication of highly dispersed/active ultrafine Pd nanoparticle supported catalysts: a facile solvent-free in situ dispersion/reduction method

The development of sustainable routes for the synthesis of noble metal supported catalysts is of high importance because of their wide applications on a large scale in the catalysis field. Herein we report a facile solvent-free solid-state dispersion route to fabricate highly dispersed ultrafine palladium nanoparticle supported catalysts. In the first step, a noble metal precursor Pd(acac)2 was dispersed spontaneously by treating the physical mixture of Pd(acac)2 and catalyst support hydroxyapatite (HAP) at 120 °C under a flow of N2. Subsequent H2 reduction results in the formation of two kinds of Pd particles. In situ reduction at 120 °C is essential for preparing highly dispersed Pd nanoparticles (∼1.2 nm, a1Pd/HAP-SSD) and cooling-down reduction leads to the formation of larger Pd nanoparticles (∼4 nm, b1Pd/HAP-SSD). The as-prepared a1Pd/HAP-SSD exhibits higher activity for phenol hydrogenation than b1Pd/HAP-SSD and that obtained by a traditional wet impregnation method, due to the highly dispersed ultrafine Pd0 nanoparticles obtained by in situ dispersion/reduction. Compared with conventional wet chemistry-based methods, the synthesis route in this work simplifies the synthesis process, avoids producing large polluted wastes, and enhances the dispersion of noble metals. This may open a new way to prepare highly dispersed/active noble metal supported catalysts and is also potentially of high importance for the green production of noble metal supported catalysts on a large scale in the future.