Qianming Gong

Sonophotocatalytic degradation of methyl orange by carbon nanotube/TiO2 in aqueous solutions

In this study, carbon nanotubes (CNTs)/TiO2 composite were prepared and the sonophotocatalytic activity of CNTs/TiO2 nanoparticles was investigated, in which methyl orange (MO) was chosen as an object. The results indicate that the photocatalytic efficiency of CNTs/TiO2 remarkable increases in the presence of ultrasound, and the sonophotocatalysis process followed a first-order kinetics. The kinetic constant of CNTs/TiO2 for the MO degradation is 2.2 times higher than that of P25, which indicated that the sonophotocatalytic ability of CNTs/TiO2 is obviously higher than P25 powder.

Chemical vapor infiltration tailored hierarchical porous CNTs/C composite spheres fabricated by freeze casting and their adsorption properties

Carbon nanotubes (CNTs) are one of the most promising candidates as adsorbents in many fields due to their unique structural characteristics. In this paper, hierarchical porous CNTs/carbon (CNTs/C) composite spheres were prepared and their strength and adsorption of vitamin B12 (VB12) were investigated. The initial porous CNT spheres were fabricated by freeze casting followed by freeze drying. Afterwards, the primary porous CNT spheres were further reinforced and tailored by chemical vapor infiltration (CVI) and steam activation. Consequently, the composite CNTs/C spheres with hierarchical porous structure and high strength were successfully fabricated. SEM and polarized light microscopy observations showed that, in addition to macro-sized radial through-pores in the spheres, many micro-sized pores were distributed uniformly in the wall of the radial tunnel-like through-pores. Mercury porosimetry and BET tests indicated that the width of the radial lamellar channels was about 5–15 μm, and the average diameter of the mesopores was about 3.8 nm. Adsorption of VB12 for these hierarchical porous CNTs/C spheres could reach 51.48 mg g−1, which is about 3.7 and 3.4 times those of traditional activated carbon beads and macroporous resin beads, respectively.

A gelatin composite scaffold strengthened by drug-loaded halloysite nanotubes

Mechanical properties and anti-infection are two of the most concerned issues for artificial bone grafting materials. Bone regeneration porous scaffolds with sustained drug release were developed by freeze-drying the mixture of nanosized drug-loaded halloysite nanotubes (HNTs) and gelatin. The scaffolds showed porous structure and excellent biocompatibility. The mechanical properties of the obtained composite scaffolds were enhanced significantly by HNTs to >300%, comparing to those of gelatin scaffold, and match to those of natural cancellous bones. The ibuprofen-loaded HNTs incorporated in the scaffolds allowed extended drug release over 100h, comparing to 8h when directly mixed the drug into the gelatin scaffold. The biological properties of the composite scaffolds were investigated by culturing MG63 cells on them. The HNTs/gelatin scaffolds with excellent mechanical properties and sustained drug release could be a promising artificial bone grating material.

Fabrication of uniform porous CNTs/activated carbon composite spheres by oil-drop method in stratified oils and their adsorption of VB12

Presented is a flexible route to prepare uniform porous carbon nanotubes/activated carbon (CNTs/AC) composite spheres with high adsorption capacity. In this work, CNTs were firstly dispersed in ethanol aqueous solution of phenolic formaldehyde (PF) resin and then the transitional CNTs/PF composite spheres were synthesized by an oil-drop method. Meanwhile the CNT suspension drops were gradually cured in stratified oils with different densities. Subsequently, after being carbonized at 600 °C, steam activated at 800 °C and followed by alkali and deionized water wash, the resultant porous CNTs/AC composite spheres were acquired with CNTs of more than 65 wt%. Remarkably, the adsorption of VB12 by the CNTs/AC composite spheres was as high as 60.36 mg g−1, which was 4.32 and 3.96 times that of activated carbon beads and macroporous resin beads, respectively. Observations and microstructure analyses indicated that the good sphericity of the CNTs/AC spheres could be attributed to the suspended state of the CNTs/PF drops during curing which was supported by the stratified oils, and that the interconnected porous structure should be developed synergistically by ethanol and water evaporation during curing, carbonization of PF resin and activation of CNTs/AC spheres.

Influence of Functional Groups on the Dispersion of TiO2 Particles on Carbon Nanotube

In this work, the functional groups on acid-treated and heat-treated carbon nanotubes (CNTs) were investigated by Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy. The morphology of the TiO2 particles decorated on the two kinds of CNTs was also studied, respectively. The results indicated that the functional groups could adsorb ions in the aqueous solution due to their electronegativity and benefit for the well dispersion of TiO2.The mechanism of TiO2 well dispersion on CNTs surface was also discussed.

Synthesis of porous carbon nanotubes/activated carbon composite spheres and their application for vitamin B12 adsorption

Abstract In this paper, carbon nanotubes (CNTs) were added to activated carbon to enhance the mesopores. At first, different amounts of CNTs were added to phenolic resin and composite spheres were synthesized by suspension polymerization. Then, by carbonizing these spheres at 600°C followed by steam activation at 850°C for more than 90 min, we prepared highly developed porous CNTs/activated carbon composite spheres. The composite spheres were characterized by a laser particle size analyzer, scanning electron microscopy, Raman spectrum, and nitrogen adsorption-desorption isotherms. Results showed that the composite spheres had good sphericity even with high proportion of CNTs (45 wt.%). Analysis also showed that the pore size distribution of the composite spheres containing CNTs was “multi-peak”, especially with 20–100-nm pores. The improved 20–100-nm porous structures in the composite spheres can be ascribed to aggregated pores of CNT bundles. The amount of vitamin B12 adsorbed on the 45 wt.% CNT composite spheres was as high as 32.38 mg/g. The spheres could be used as adsorbents for middle-molecular-weight toxins or large molecules in hemoperfusion.

Densification of in situ prepared mesocarbon microbead/carbon nanotube composites by hot-press sintering

In situ prepared mesocarbon microbead/carbon nanotube (MCMB/CNT) composites are potential precursors of high density carbon materials for various applications. Integrated MCMB/CNT composites were successfully fabricated by hot-press sintering at 550℃ under 30 MPa. After further calcination at 900℃, the hot-press sintering fabricated MCMB block has an apparent density of 1.77 g/cm^3 and the open porosity 5.1%. With the addition of 5% (mass fraction) CNTs, the density of the composite block is elevated to 1.84 g/cm^3, and its open porosity is reduced to 3.5%. The flexural strength of composite block with 5% CNTs is elevated to 116 MPa. Through the hot-press sintering, pores of 10-50 nm in the calcinated bulks are remarkably eliminated. The interstice between microbeads in the composite blocks is filled up by CNTs together with β-resin and quinoline-insoluble spheres, which can further contribute to the densification.

Hierarchically Mesostructured Aluminum Current Collector for Enhancing the Performance of Supercapacitors

Aluminum (Al) current collector is one of the most important components of supercapacitors, and its performance has vital effects on the electrochemical performance and cyclic stability of supercapacitors. In the present work, a scalable and low-cost, yet highly efficient, picosecond laser processing method of Al current collectors was developed to improve the overall performance of supercapacitors. The laser treatment resulted in hierarchical micro-nanostructures on the surface of the commercial Al foil and reduced the surface oxygen content of the foil. The electrochemical performance of the Al foil with the micro-nanosurface structures was examined in the symmetrical activated carbon-based coin supercapacitors with an organic electrolyte. The results suggest that the laser-treated Al foil (laser-Al) increased the capacitance density of supercapacitors up to 110.1 F g-1 and promoted the rate capability due to its low contact resistance with the carbonaceous electrode and high electrical conductivity derived from its larger specific surface areas and deoxidized surface. In addition, the capacitor with the laser-Al current collector exhibited high cyclic stability with 91.5% capacitance retention after 10 000 cycles, 21.3% higher than that with pristine-Al current collector due to its stronger bonding with the carbonaceous electrode that prevented any delamination during aging. Our work has provided a new strategy for improving the electrochemical performance of supercapacitors.

Reaction Mechanism of Cu(In, Ga)Se2 Formation During Milling Process of Powder Mixture of Cu2Se, In2Se3 and Ga2Se3

Sputtering targets of CIGS quaternary ceramic were fabricated by hot-press sintering the milled powder mixture of Cu2Se, In2Se3 and Ga2Se3. When the milling time of the powders less than 4 h, the sintered targets delaminated, while the delamination disappeared with the prolonging milling time. Therefore the physico-chemical changes of the powder mixture during the milling process and their influence on the delamination of the targets were investigated. The results indicate that with the progress of the milling process, mechanical alloying (MA) occurred, and chalcopyrite Cu(In, Ga)Se2 (CIGS) formed from Cu2Se, In2Se3 and Ga2Se3; With the increasing milling time, CuInSe2 (CIS) formed on the surface of binary copper selenide firstly and CIGS was subsequently generated due to the inward diffusion of Ga; Thus the original blend powders became a mixture of CIGS and residual Ga2Se3 after milling for 48 h. Since CIGS and Cu2-xSe have a similar crystallographic structure, therefore this epitaxial relation may facilitate the formation of CIGS. The disappearance of Cu-Se binary compound and the formation of CIGS restrained the delamination of the CIGS targets in the sintering process.