Shuge Peng

Hollow mesoporous silica supported ruthenium nanoparticles: a highly active and reusable catalyst for H 2 generation from the hydrolysis of NaBH 4

Ru nanoparticles supported on hollow mesoporous silica (HMS), which are prepared via in situ wet chemical reduction, have been investigated as the highly efficient heterogeneous catalyst for H2 generation from the hydrolysis of an alkaline NaBH4 solution. Many techniques, including X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS), are used to characterize the as-prepared nanocatalyst (Ru/HMS). Factors, such as Ru loadings in HMS, catalyst concentration, and solution temperature, on catalytic property and reutilization are investigated in this work. A rate of H2 generation as high as 18.6 L min-1 g-1 (Ru) using 1 wt% NaBH4 solution containing 3 wt% NaOH and 40 mg of Ru/HMS catalyst can be reached at room temperature. The minimum apparent activation energy (Ea) of H2 generation, obtained by fitting the curve of Ea values versus catalyst amount, is determined to be 46.7 ± 1 kJ/mol. The residual catalytic activity of the repeated Ru/HMS still remains 47.7% after 15 runs, which perhaps results from the incorporation of the residual by-product (NaBO2) in the pores of HMS based on the analysis of XPS.

Surface Modification of Graphene Oxide by Carboxyl-Group: Preparation, Characterization, and Application for Proteins Immobilization

Two-dimensional grapheme offers interesting electronic, thermal, and mechanical properties that are currently being explored for advanced electronics, membranes, and composites. Here we synthesize and explore the biological applications of grapheme oxide. The functionalization chemistry was developed to impart solubility and compatibility of grapheme oxide in biological environments. We found that the global myoglobin (Mb) – grapheme oxide hybrids (Mb-GO) could be successfully prepared by chemical deposition via carboxylic acid modified graphite oxide (GO-COOH) as the intermediate under mild conditions. The functioned grapheme oxide was characterized by many techniques including UV-Vis, FT-IR, Raman, SEM, and TEM. The results indicated that the hydroxyl groups and epoxide groups could be converted to carboxylic acid moieties under strongly basic conditions, and the carboxylic acid modified graphite oxide had increased water solubility and more carboxylic acid groups available for subsequent enzyme immobilization by covalent binding. The average amount of carboxylic acid groups in GO-COOH were determined to be 1.243 mmol in 100 mg GO-COOH by acid-base titration. And the average mole percentage of the carboxylic acid groups on GO-COOH was about 14.9%. The funcitionalization of GO with carboxylic acid groups provided basis for constructing various function materials, including biosensors, enzyme reactors, cellular imaging, and drug delivery.

Water Dispersible Ru (0) Nanorods: A Highly Efficient Heterogeneous Catalyst for the Hydrogen Generation from Sodium Borohydride Solutions

Water-dispersible Ru (0) nanorods stabilized by Poly (N-vinyl-2-pyrrolidone) (PVP) were employed as catalyst in the hydrolysis of sodium borohydride (NaBH4). The hydrogen generation rate was determined as a function of solution temperature, NaBH4 concentration, and catalyst amount. Ru (0) nanorods were found to be highly active catalysts even at room temperature. Kinetics study indicated that the hydrolysis reaction was first order in catalyst concentration and zeroth order in substrate concentration. The activation parameters of the hydrolysis reaction were also determined from the evaluation of the kinetic data. The PVP-stabilized Ru (0) nanorods provided a lower apparent activation energy (Ea = 33.4 ± 1 kJ/mol) than bulk Ru(0) metal and other reported Ru-based supported catalysts for the hydrolysis of NaBH4.

Effect of polyethyleneimine modified graphene on the mechanical and water vapor barrier properties of methyl cellulose composite films

A series of novel methyl cellulose (MC) composite films were prepared using polyethyleneimine reduced graphene oxide (PEI-RGO) as an effective filler for water vapor barrier application. The as-prepared PEI-RGO/MC composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, tensile test and scanning electron microscopy. The experimental and theoretical results exhibited that PEI-RGO was uniformly dispersed in the MC matrix without aggregation and formed an aligned dispersion. The addition of PEI-RGO resulted in an enhanced surface hydrophobicity and a tortuous diffusion pathway for water molecules. Water vapor permeability of PEI-RGO/MC with loading of 3.0% of surface modified graphene was as low as 5.98×10-11gmm-2s-1Pa-1. The synergistic effects of enhanced surface hydrophobicity and tortuous diffusion pathway were accounted for the improved water vapor barrier performance of the PEI-RGO/MC composite films.

The Adaptive Tribological Investigation of Polycaprolactam/Graphene Nanocomposites

The design and mechanism of adaptive materials in the field of tribology are of particular importance because of the tribological properties greatly depending on the operating conditions and external environment. Polycaprolactam (PCL) adaptive nanocomposites containing porous graphene impregnated with solid paraffin were prepared by in situ polymerization. The tribological results showed that the designed nanocomposites, which displayed adaptive tribological behaviors, had low and stable friction coefficients and the wear rates compared to neat PCL even under high pressure and velocity condition. The proposed adaptive tribological mechanisms are due to the high load-carrying capabilities of graphene nanosheets forming proper surface texture, the lubricating role of molten paraffin produced at sliding interface under friction heating and the mitigated thermal damage caused by lower surface temperature through depleting friction heat. The as-prepared polycaprolactam composites are expected to broaden the application of such polymers in engineering parts, and the design concept can easily apply to other self-adaptive tribological composites.

Amino-group Hybrid Magadiite Support: Preparation, Characterization, and Application for Hydrogen Generation

A simple method of preparing durable magadiite-supported catalyst for hydrogen generation was developed in this article. This magadiite-supported catalyst was the structure of ruthenium nanoparticles immobilized on the surface of amino-group hybrid magadiite. The amino-group hybrid magadiite support (NH2-magadiite) was successfully prepared by oxidation and chemical coupling reaction, and then was used as the template to trap Ru nanoparticles (Ru/NH2-magadite). Many techniques were used to characterize the structure of amino-group hybrid magadiite and the morphology of the supported Ru nanoclusters, including UV-Vis, FT-IR, XRD, SEM, TEM and EDX. The hydrolysis of alkaline sodium borohydride (NaBH4) solution was used as probe to evaluate the catalytic activity of the supported Ru catalysts by NH2-magadiite and Na-magadiite supports, respectively. The results show that amino group was successfully grafted on the external surface of magadiite, and Ru nanoparticles could be trapped evenly onto the external of magadiite by the NH2-magadiite support template. Ru/NH2-magadite catalyst shows higher catalytic activity than that of Na-magadiite supported Ru catalyst (Ru/Na-magadiite). Highly dispersed Ru nanoparticles on the external surface of NH2-magadiite support played an important role in improving catalytic activity of NaBH4 hydrolysis.

Kinetic Study of Hydrogen Generation from the Hydrolysis of Alkaline NaBH4 over Ru/MMT: an Insight on the Effect of Catalyst Amount

An efficient and cheap catalyst, montmorillonite supported Ru nanoclusters (Ru/MMT) were successfully prepared and explored for the hydrogen generation from alkaline NaBH4 solution. The catalytic behavior and the kinetics of Ru/MMT catalyzed hydrolysis of alkaline NaBH4 was studied detailedly by measuring the volume of generated hydrogen gas varying catalyst concentration and temperature. The relationship between the activation energy (Ea) of NaBH4 hydrolysis reaction and Ru/MMT amount was constructed, and the minimum value was determined to be 49.6 kJ/mol, which was lower than the most reported Ru-based supported catalysts that have been reported in the open literatures. The higher catalytic activity of Ru/MMT was due to the more open frame of montmorillonite than the other inorganic supporters, which decreases the substrate inhibition in catalytic hydrolysis of NaBH4.

Silica /polydicyclopentadiene nanocomposites: Preparation, characterization, and mechanical properties

ABSTRACT Silica/poly-dicyclopentadiene (SiO2/poly-DCPD) nanocomposites with improved mechanical properties were successfully prepared by in-situ ring-opening metathesis polymerization (ROMP) using reaction injecting molding (RIM) technique in this work. To improve the interfacial compatibility between SiO2 nanoparticles and poly-DCPD matrix, polystyrene (PS) was chemically modified onto the surface of SiO2 nanoparticles to obtain oil-soluble polystyrene coated silica spheres with core-shell structure (PS@SiO2). The mechanical behaviors of SiO2 /poly-DCPD nanocomposites with different PS@SiO2 content have been investigated in detail. The improved mechanical properties of SiO2 /poly-DCPD nanocomposites were mainly attributed to the well interfacial compatibility between the PS shell layer of PS@SiO2 spheres and poly-DCPD matrix, which resulted from the swelling of DCPD monomer in PS shell before polymerization.

In-situ polymerization of silica/polydicyclopentadiene nanocomposites: Improved tribological properties and evaluation of interfacial compatibility

ABSTRACT Polymer materials concluding polydicyclopentadiene (poly-DCPD) are widely used in engineering fields but have low load-carrying capacities which limit its widely application. SiO2/poly-DCPD nanocomposites were prepared by in situ polymerization in this work. polystyrene (PS), chemically modified onto the surface of SiO2 nanoparticles to obtain oil-soluble polystyrene coated silica spheres with core-shell structure (PS@SiO2), was used to improve the interfacial compatibility between SiO2 nanoparticles and poly-DCPD matrix. Field-emission scanning electron microscope (FESEM) was used to observe and evaluate the interfacial structure of SiO2/poly-DCPD nanocomposites. The tribological behaviors of SiO2 /poly-DCPD nanocomposites with different PS@SiO2 loading have been investigated detailly in this work. The results showed that the addition of PS@SiO2 nanospheres could greatly decrease friction coefficient and wear rate of the SiO2/poly-DCPD nanocomposites, especially when the loading of PS@SiO2 nanospheres arrived to 4 wt%. The well interfacial compatibility between the PS shell layer of PS@SiO2 spheres and poly-DCPD matrix should be resposible for the improved tribological properties of SiO2 /poly-DCPD nanocomposites.

PVP-stabilized Ru colloidal nanoparticles by solvothermal synthesis: Preparation, characterization, and catalytic properties

ABSTRACT Stable poly (N-vinyl-2-pyrrolidone)-stabilized ruthenium colloidal nanoparticles (PVP-Ru) were prepared by solvothermal method; n-butyl alcohol, a low boiling point alcohol, was used as the reductant and solvent and PVP (polyvinyl pyrrolidone) served as protecting agents. PVP-Ru nanoparticles were characterized by UV-Vis absorbance spectra (UV-Vis), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier Transform Infrared Spectroscopy (FT-IR). The PVP-Ru colloidal nanoparticles were applied to catalytic oxidization of ethanol to evaluate the catalytic activity, and the products were analyzed by gas chromatograph (GC). The results showed that the average diameter of the Ru nanoparticles was 1.23 nm with a narrow distribution. X-ray photoelectron spectroscopy verified that Ru was in the metallic state. The PVP-Ru colloidal nanoparticles possessed high catalytic activity and selectivity for the oxidation of gas ethanol to acetaldehyde.