Chengzhong Yu

High‐Yield Synthesis of Periodic Mesoporous Silica Rods and Their Replication to Mesoporous Carbon Rods

Ordered mesoporous carbon rods have been obtained in high yield using silica rods as templates. The inorganic salts that are used for the synthesis of the silica templates control the morphology and adjust the wall structure of the mesoporous silica materials and thus of the final carbon rods. The Figure shows a TEM image of a carbon sample synthesized using SBA-15-100 silica as a template.

Functional Nanoporous Graphene Foams with Controlled Pore Sizes

A simple hydrophobic-affinity-derived assembly approach to pack graphene sheets into a nanoporous foam structure has been developed. Nanoporous graphene foams with the highest pore volume and large surface area are obtained. The pore diameter of the graphene foams can be finely adjusted from the mesopore to the macropore range by employing spherical templates with different sizes.

Poly-l-lysine Functionalized Large Pore Cubic Mesostructured Silica Nanoparticles as Biocompatible Carriers for Gene Delivery

Large pore mesoporous silica nanoparticles (LP-MSNs) functionalized with poly-L-lysine (PLL) were designed as a new carrier material for gene delivery applications. The synthesized LP-MSNs are 100-200 nm in diameter and are composed of cage-like pores organized in a cubic mesostructure. The size of the cavities is about 28 nm with an entrance size of 13.4 nm. Successful grafting of PLL onto the silica surface through covalent immobilization was confirmed by X-ray photoelectron spectroscopy, solid-state (13)C magic-angle spinning nuclear magnetic resonance, Fourier transformed infrared, and thermogravimetric analysis. As a result of the particle modification with PLL, a significant increase of the nanoparticle binding capacity for oligo-DNAs was observed compared to the native unmodified silica particles. Consequently, PLL-functionalized nanoparticles exhibited a strong ability to deliver oligo DNA-Cy3 (a model for siRNA) to Hela cells. Furthermore, PLL-functionalized nanoparticles were proven to be superior as gene carriers compared to amino-functionalized nanoparticles and the native nanoparticles. The system was tested to deliver functional siRNA against minibrain-related kinase and polo-like kinase 1 in osteosarcoma cancer cells. Here, the functionalized particles demonstrated great potential for efficient gene transfer into cancer cells as a decrease of the cellular viability of the osteosarcoma cancer cells was induced. Moreover, the PLL-modified silica nanoparticles also exhibit a high biocompatibility, with low cytotoxicity observed up to 100 μg/mL.

Cheap and scalable synthesis of α-Fe2O3 multi-shelled hollow spheres as high-performance anode materials for lithium ion batteries

Delicate α-Fe2O3 multi-shelled hollow spheres have been prepared by a simple and scalable spray drying method followed by annealing in air. The resulting material shows high specific capacity, good cycling stability, and excellent rate performance in lithium ion battery applications.

Hyaluronic acid modified mesoporous silica nanoparticles for targeted drug delivery to CD44-overexpressing cancer cells

In this paper, a targeted drug delivery system has been developed based on hyaluronic acid (HA) modified mesoporous silica nanoparticles (MSNs). HA-MSNs possess a specific affinity to CD44 over-expressed on the surface of a specific cancer cell line, HCT-116 (human colon cancer cells). The cellular uptake performance of fluorescently labelled MSNs with and without HA modification has been evaluated by confocal microscopy and fluorescence-activated cell sorter (FACS) analysis. Compared to bare MSNs, HA-MSNs exhibit a higher cellular uptake via HA receptor mediated endocytosis. An anticancer drug, doxorubicin hydrochloride (Dox), has been loaded into MSNs and HA-MSNs as drug delivery vehicles. Dox loaded HA-MSNs show greater cytotoxicity to HCT-116 cells than free Dox and Dox-MSNs due to the enhanced cell internalization behavior of HA-MSNs. It is expected that HA-MSNs have a great potential in targeted delivery of anticancer drugs to CD44 over-expressing tumors.

An Ordered Mesoporous Carbon with Short Pore Length and Its Electrochemical Performances in Supercapacitor Applications

The pores of conventional ordered mesoporous carbons (OMCs) are usually over several micrometers in length, making it difficult for electrolyte access and ion diffusion to the deep pores of the carbon grains when they are used as the electrode of electrochemical double layer capacitors (EDLCs). We have synthesized an ordered mesoporous carbon with a much shorter pore length of 200-300 nm through a hard-template method. The electrochemical properties as an electrode material for EDLC were investigated in an alkaline solution in comparison with the conventional OMC. A maximum capacitance of 14 mu F/cm(2) was obtained for this short pore length OMC (SOMC) in 6 M KOH solution compared with 10 mu F/cm(2) of the conventional OMC. SOMC delivered much better capacity retention than the conventional OMC in lower concentration electrolyte solution. The superior performance of SOMCs was attributed to its having more entrances for electrolyte accessibility and a short pathway for rapid ion diffusion. (c) 2007 The Electrochemical Society.

Anionic surfactant induced mesophase transformation to synthesize highly ordered large-pore mesoporous silica structures

Successive mesophase transformation induced by an anionic surfactant such as sodium dioctyl sulfosuccinate (AOT) has been demonstrated to fabricate four kinds of large pore mesoporous silica materials in a triblock copolymer F127 surfactant assembly system. The transformation of the highly ordered mesostructures from face-centered cubic (space group Fmm) to body-centered Imm then towards two-dimensional (2-D) hexagonal p6m and eventually to cubic bicontinuous Iad symmetries has been achieved by tuning the amount of AOT and 1,3,5-trimethylbenzene (TMB). Characterization by small-angle X-ray scattering (SAXS), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 sorption isotherms reveals that all mesoporous silica structures have highly ordered regularity in large domains and possess high surface areas, large pore volumes and uniform pore sizes. The expansion of hydrophobic volume in the amphiphilic Pluronic F127 surfactant associated with AOT and TMB molecules in an acidic media is attributed to the observed mesophase transformation. A further swelling of the surfactant micelles can be achieved by adding TMB molecules into the mixed AOT and F127 surfactants system due to their synergistic solubility enhancement, which gives rise to a long-range ordered 2-D hexagonal mesoporous silica structure with very large cell parameter (a = 16.5 nm) and pore size (∼12 nm). The understanding of the blend–surfactant assembly mechanism will lead to a more rational approach for economical and large-scale production of mesoporous materials with controllable structures.

Synthesis of Ordered Mesoporous Carbon Monoliths with Bicontinuous Cubic Pore Structure of Ia3d Symmetry

Large-diameter-sized mesoporous carbon monoliths with bicontinuous cubic structure of Ia3d symmetry have been synthesized by using mesoporous silica monoliths as hard templates; such carbon monoliths show potential application of advanced electrodes and electrochemical double layer capacitors.

Surfactant-Free Assembly of Mesoporous Carbon Hollow Spheres with Large Tunable Pore Sizes

Mesoporous carbon hollow spheres (MCHS) have wide applications, including catalysis, absorption, and energy storage/conversion. Herein, we report a one-pot, surfactant-free synthesis of MCHS using three molecules: resorcinol, formaldehyde, and tetrapropyl orthosilicate. The co-condensation process between the in situ generated silica primary particles and the polymer oligomers is regulated, leading to monodispersed MCHS with adjustable pore sizes from micropores to 13.9 nm. The resultant MCHS shows excellent performance for electrochemical double-layer capacitors with high capacitance (310 F g(-1) at 1 A g(-1)), excellent rate capability (157 F g(-1) at 50 A g(-1)), and outstanding cycling stability (98.6% capacity retention after 10 000 cycles at 10 A g(-1)). Our one-pot synthesis strategy is versatile and can be extended to fabricate metal oxide@mesoporous carbon yolk-shell structures in the absence of surfactant, paving the way toward designed synthesis of nanostructured mesoporous carbon composites for various applications.

A Facile One‐Step Solvothermal Synthesis of SnO2/Graphene Nanocomposite and Its Application as an Anode Material for Lithium‐Ion Batteries

Spare capacity: A SnO/graphene nanocomposite is fabricated by a novel solvothermal method (see picture). The nanocomposite exhibits a reversible lithium storage capacity of 838 mAhg in the first cycle and improved cyclability as an anode material for lithium-ion batteries.