The mesoporous titanium oxides- and carbide-carbon nanocomposites (Ti-C nanocomposites) with different morphologies at various Ti/C mass ratios were directly synthesized via supramolecular self-assembly with in situ crystallization process. The microstructures including surface area, morphology, and crystallinity were characterized by surface area analyzer, TEM, and SAXS/ XRD, respectively. The specific BET surface areas (178-639 m²g ^-1), micropore surface areas (6.3-47.3%), and total pore volumes (0.18-0.46 cm³g^-1) increase with the increase in calcination temperatures and Ti/C mass ratios. The calcination temperature and carbon content have significant effect, on the thermal stability of titanium-based nanomaterials. The crystallinity changes from anatase, rutile, Magneli phases, and. then to TiC when the carbon content is lower than 35 wt %, while the crystal phase of Ti-C composites at 50 wt % changes directly from anatase to TiC. However, Mageli products lose the mesostructures. The sizes Of TiO₂ nanocrystals are in the range 2.6-9.7 nm, and. increase with increasing temperature to slightly distort the ordered mesostructured regularity up to 800 °C, and low distorted octahedrons with 6-fold coordinated titanium carbide are formed at 1000 °C. In addition, the graphitized carbons, determined by sp²- and sp³-bonded carbon contents from XAS spectra, increased upon increasing calcination temperature, depicting the increase in graphitization after calcination. Results obtained in this study allow us to elucidate the micro-structural changes of titanium-based materials inside the highly ordered mesoporous carbon matrices and open an avenue to the design and synthesis of a multitude of cooperatively functional organic-inorganic materials with attractive novel properties.

Chun Hsien Huango;Dong Gu;东元 赵;Ruey An Doong

Chemistry of Materials

2010-3-9

Fuctionalization of porous carbon materials through chemical methods orientates the development of new hybrid materials with specific functions. In this paper, a comprehensive study of pore evolution, mesostructural oxidation resistance, and simultaneous surface functionalization of ordered mesoporous carbon FDU-15 under various oxidation conditions is presented for the first time. The mesostructure and pore evolution with increasing oxidative strength are retrieved from XRD, TEM, and N₂ sorption techniques. The textural properties can be conveniently manipulated by changing the oxidation parameters, including different oxidative solution, temperature, and duration. It is revealed that the mesoporous carbon FDU-15 shows excellent structural stability under severe oxidation treatments by acidic (NH₄) ₂S₂O₈,HNO₃, and H₂O ₂ solutions, much more stable than the mesostructural analogue CMK-3 carbon prepared by the nanocasting method. The surface area and porosity deteriorate to a large extent compared to the pristine carbon, with the micropores/small mesopores as the major contribution to the deterioration. The micropore/small mesopore can be blocked by the attached surface oxides under mild oxidation, while reopened with more carbon layer dissolution under more severe conditions. Simultaneously, high densities of surface oxygen complexes, especially carboxylic groups, can be generated. The contents and properties of the surface oxygen-containing groups are extensively studied by FTIR, TG, elemental analyses, and water and ammonia adsorption techniques. Such surface-functionalized mesoporous carbons can be used as a highly efficient adsorbent for immobilization of heavy metal ions as well as functional organic and biomolecules, with high capacities and excellent binding capabilities. Thus, we believe that the functionalized mesoporous carbon materials can be utilized as a promising solid and stable support for water treatment and organic/ biomolecules immobilization and may be applicable in drug delivery, separation, adsorption technology, and columns for GC and HPLC systems in the near future.

Zhangxiong Wu;Paul A. Webley;东元 赵

Langmuir

2010-6-15

We report the fabrication of gold nanotube arrays by means of a direct electrodeposition method utilizing nanochannel alumina templates. The observations by SEM and TEM show that gold nanotubes were obtained within the alumina template with different pore diameters. The mechanism related to the morphology formation is discussed. The sensing applications of the gold nanotube arrays have been investigated by using square-wave voltammetry and cyclic voltammetry. The gold nanotube arrays exhibit low-potential electrocatalytic detection of hydrogen peroxide with high sensitivity and show promise for biosensing applications.

Xinyi Zhang;Huanting Wang;Laure Bourgeois;Renji Pan;东元 赵;Paul A. Webley

Journal of Materials Chemistry

2008

Herein, free-standing supertubes, composed of a single layer of close-packed carbon-coated nanoparticles, are fabricated by a confined-epitaxial-assembly strategy. Benefiting from the tubular geometry, monolayer superlattice structure, and uniform and conformal carbon coating, such free-standing supertubes promise high electrochemical performance while simultaneously serving as a robust platform for reliably elucidating the structure-performance relationship of lithium-ion batteries (LIBs). As a model, Fe₃O₄ supertubes, when used as LIB anodes, can deliver a capacity of ∼800 mAh g⁻¹ after 500 cycles at 5 A g⁻¹, outperforming most Fe₃O₄-based materials reported previously. More importantly, the structural evolution of Fe₃O₄ supertubes is revealed at meso-/nano-/atomic scales simultaneously upon lithiation and delithiation, which correlates well with the battery's capacity reactivation, stabilization, and degradation behaviors during the course of 500 cycles. Complex nanostructures are expected to outperform their simple counterparts with enhanced electrochemical performance. Investigating the complex structural evolution of active materials with electrochemical performance is a crucial step toward the development of high-performance electrochemical devices. Herein, free-standing supertubes comprising a monolayer of carbon-coated nanoparticles enabling homogeneous electrochemical process have been fabricated. Such supertubes provide a fundamentally important platform capable of revealing long-term structural evolution on multiple length scales, the better understanding of which may provide insights into the device operation mechanisms and shed light on the rational design of high-performance electrode materials. Given the flexibility in tuning nanoparticle composition, it is anticipated that such supertubes may serve as a platform for elucidating the structure-performance relationship of many other energy-storage and energy-conversion devices. Well-defined supertubes, which integrate the merits of the tubular geometry, conformal carbon coating, and nanoparticle monolayer superlattice structure, are designed and fabricated by a confined-epitaxial-assembly method. Such self-assembled supertubes, when evaluated as electrode materials for lithium-ion batteries, exhibit superior electrochemical performance while also providing a fundamentally important platform capable of visually revealing a structure-performance relationship on multiple length scales over long-term cycling.

Tongtao Li;Biwei Wang;Jing Ning;Wei Li;Guannan Guo;Dandan Han;Bin Xue;Jinxiang Zou;Guanhong Wu;Yuchi Yang;Angang Dong;东元 赵

Matter

2019-10-2

Control of porosity and structure and modification of surface and framework are the golden rules to adapt carbon materials to targeted applications. The former has been fairly well developed for the soft-templated FDU-type mesoporous carbons while there is still a large need for the latter. In this paper, a simple post-synthetic route is adopted to incorporate nitrogen-containing functionalities into the frameworks of these carbon materials. The basic principle relies on the confinement of melamine molecules in the mesochannels of an ordered mesoporous carbon matrix such that they self-condense into carbon nitride uniformly dispersed under a heat treatment at ∼500 °C and subsequently lead to the formation of mesoporous nitrogen-enriched carbon materials at 700-900 °C with well-retained ordered mesostructure and high surface area. The structure, porosity, composition and the nitrogen-containing functionalities are extensively studied. The integration of regular and open mesostructure, uniform and large mesopore size, high mesoporosity, and nitrogen enrichment makes these materials highly efficient for phenol removal, not only through physisorption with fast adsorption kinetics and large capacity but also by a newly found photo-degradation property with remarkable catalytic activity. Furthermore, the mesoporous nitrogen-enriched carbons deliver promising properties for CO ₂ capture with greatly enhanced heats of adsorption and well-retained high capacity. Given that the FDU-type mesoporous carbon materials hold variable structures, tunable pore sizes, flexible morphologies and an ease for large-scale synthesis, the success in nitrogen-enrichment would significantly accelerate the progress of their practical applications in pollution control, environment management, supercapacitors and fuel cells.

Zhangxiong Wu;Paul A. Webley;东元 赵

Journal of Materials Chemistry

2012-6-14

Porous Pt nanowire arrays show enhanced electrocatalytic activities for ethanol oxidation in direct alcohol fuel cells.

Xinyi Zhang;Wei Lu;Jiyan Da;Huanting Wang;东元 赵;Paul A. Webley

Chemical Communications

2009

X-ray standing wave enhanced scattering effects are observed in mesoporous silica thin films (MSTFs) deposited on rough indium tin oxide coated glass substrates in grazing-incidence small-angle x-ray scattering studies. The distorted-wave Born approximation theory along with a rigorous wave function analysis is employed to elucidate the dynamical scattering processes occurring in MSTFs. The data analysis is significantly simplified by expressing the x-ray scattering intensity from MSTFs in two separate functions of the wave vector transfer, where the in-plane correlation between neighboring mesopore channels is decoupled from the out-of-plane interference interaction. Remarkable agreement is achieved between experiment and theory.

Longlong Wu;Yupu Liu;Xiao Wang;Geng Wang;东元 赵;Gang Chen

Applied Physics Letters

2017-1-23

东元 赵;Ying Wan

2007

A simple mixture of thiourea and AgNO₃ in alkaline solution without any template or substrate, allowed to stand at room temperature, forms a unique self-supported pattern of Ag₂S nanorods. The picture shows a scanning electron micrograph of a typical product: a flake of polycrystalline Ag₂S with Ag₂S nanorods that radiate from a central point.

Qingyi Lu;Feng Gao;东元 赵

Angewandte Chemie - International Edition

2002-6-3

Since mesoporous silicates (M41S) were first discovered in the early 1990s, organic-inorganic assembly combined with sol-gel processes by using surfactants as structure-directing agents had been considered to be the major pathway for creating mesoscaled periodic materials. However, unfortunately, many mesostructured materials could not be prepared by the sol-gel process. Nanocasting, using highly ordered mesoporous silica as a template, has brought forward incredible possibilities in preparing novel mesostructured materials, and has led to a great number of ordered nanowire arrays with: a) small diameter (<10 nm); b) large surface areas (up to 2500 m² g ^-1) and uniform mesopores (1.5-10 nm); c) tunable 2-D or 3-D mesostructures; d) controlled morphology such as spheres, rods, films, and monoliths; and e) different components including carbon, metals, metal oxides and metal sulfides. We intend to review the results of research into replica mesostructures by nanocasting in recent years from the viewpoint of synthesis. Detailed synthetic processes are described, and problems that are often encountered in the procedure are discussed with several solutions. Many mesostructured replicas are introduced, sorted by their components, including synthetic methods, characteristics of the materials, applications and future challenges. Finally, a simple view of the prospects in this area is provided.

Haifeng Yang;东元 赵

Journal of Materials Chemistry

2005-3-28