Xin Tan

Hetero-structured TiO2/SrTiO3 nanotube array film with highly reactive anatase TiO2 {001} facets

Interest in highly reactive anatase TiO2 with controllable facets has increased rapidly in recent years because its unique properties provide new insights into the interfacial chemistry of TiO2 in applications such as photocatalysis and in its use as an electrode material. We report here the fabrication of hetero-structured TiO2/SrTiO3 nanotube arrays with a preferred orientation to the anatase TiO2 {001} facet by a typical anodization and subsequent hydrothermal approach, followed by annealing. Based on XRD, FE-SEM, FE-TEM, XPS and Raman measurements, it is shown that TiO2 is partially converted into SrTiO3 attached to in situ TiO2 nanotubes. A hetero-structured interface of TiO2/SrTiO3 with preferred growth of the anatase TiO2 {001} facet was confirmed to be formed after the hydrothermal process. The resulting hetero-structured samples were used as photocatalysts to decolorize methylene blue in aqueous solution in a photocatalytic and photoelectrocatalytic process. The hetero-structured samples show enhanced photocatalytic properties compared with the reference TiO2 nanotube arrays.

Li4Ti5O12/hollow graphitized nano-carbon composites as anode materials for lithium ion battery

Li4Ti5O12/hollow graphitized nano-carbon composites (LTO/HGCs) have been synthesized by a hydrothermal reaction using hollow graphitized nano-carbon as a conductive agent, and the composites were calcined at 750 °C for 12 h. The as-prepared particles are highly-crystalline spinel-type Li4Ti5O12 with a uniform particle size distribution, perfect crystal structure and small amounts of particle aggregation. The highly oriented hollow graphitized nano-carbon with a hexagonal carbon structure is uniformly distributed on the surface of Li4Ti5O12 nanoparticles, effectively improved the contact of Li4Ti5O12 nanoparticles. Electrochemical performance of the composites as anodes for lithium ion batteries is evaluated by galvanostatic discharge/charge, electrochemical impedance spectroscopy and cyclic voltammetry. The results show that the discharge capacity of composites with HGC (10.0 wt%) is 162.2 mA h g−1 and 105.4 mA h g−1 at the rate of 15 mA g−1 and 1.5 A g−1, respectively, and the discharge capacity retention rate after 500 cycles is 91.2% at 5C. The addition of hollow graphitized nano-carbon has improved the Li4Ti5O12 performance in terms of rate capacity, cycling life and capacity retention due to the improvement of electrical conductivity and decrease of resistance and polarization. These facts suggest that LTO/HGCs are one of the promising anode materials for high rate lithium ion batteries.

A simple and facile approach for synthesis of a free-standing TiO2 nanotube layer and its photovoltaic application

A vertically oriented, free-standing TiO2 nanotube (FS-TNT) layer was facilely fabricated via anodization and heat treatment, and the detaching mechanism of the FS-TNT layer is presented and authenticated. In addition, the closed-bottom-up FS-TNT layer after 2 h anodization facing the P25 film shows a significant improvement in the cell performance (η = 7.62%).

Characterization of Y/TiO2 Nanoparticles and their Reactivity for CO2 Photoreduction

A series of Y/TiO2 nanoparticles (NPs) were synthesized via sol-gel method. The crystal structures, morphologies and chemical properties were characterized using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). We investigated the effects of different doping amounts of Y on the reaction of CO2 photoreduction. The results shown that 0.1 wt.%Y/TiO2 (0.1YT) performed the highest photocatalytic activity, which yielded 384.62 µmol/g∙cat. formaldehyde after 6 h of UV illumination.

Experimental Study on the Ammonium Ion-Exchange Material and its Removal of Ammonia Nitrogen from Water

Washed kaolin produced in Maoming, Guangzhou was used as the raw material and NaOH and NaAlO2 were used as the modifiers to prepare a high-performance deaminating material by providing kaolin with sodium-type exchange groups through modification and calcination. Then the ammonia ion exchange capacity of this material was studied by means of Cation Exchange Capacity (CEC) determination. Research has also been done on the conditions for the preparation of this material, the factors that influence the result of the removal of ammonia nitrogen from water by this material, and the ammonia nitrogen removal rate of this material. In this study , an extruding-rounding process to make the powder material into 1-2mm grains and studied the forming process of the grains. Research results show that: The ammonia exchange capacity of the prepared material was greater than 70 mg NH4+-N/g. Laboratory static ammonia nitrogen experiment showed that the high-performance ammonia deaminating material could remove 90% of the ammonia nitrogen from water and were qualified for the removal of ammonia nitrogen in water treatment processes. Through the establishment of Pseudo-first reaction kinetic model and Pseudo-second reaction kinetic model of modified of kaolin absorption on NH4+, we can see that the adsorption of ammonia nitrogen in water by this ammonium ion-exchange material matches the pseudo-second-order reaction.

Research on Characterization and Application of High-Performance Ion Exchange Material

The object of this research is to investigate the removal of nitrogen in the form of ammonium ion (NH4+-N) from aqueous solutions using Na-form of high-performance ammonium ion-exchange material. The Chinese Kaolin from the province of Guangzhou is used as the raw material and modified to prepare the ion-exchange materials. According to CEC measurement, the obtained ammonium ion-exchange material had an ammonium ion exchange capacity greater than 75mgNH4+-N/g and can be used to remove ammonia nitrogen in water treatment. In this paper, several surface feature evaluation methods（SEM、XPS、IR）are used to discuss and analyze the modification process of kaolin and the action mechanism and modification results of the ammonia ion exchange material.

Building a System Dynamic Model of Regional Low-Carbon Development

The development of low-carbon economy is considered as a top-down economic transformation driven by policy. The realization of low-carbon economy is not simply been technical but policy-making methods need to be conducted in-depth research. This paper delivers a policy influence research method by constructing a regional low-carbon development model based on System Dynamics, and validates this model by comparing the simulation data and the Chinese calendar year statistics. Finally, some policy making suggestions based on the research are provided.

New Reactor Fabricated Using Light Leakage Fiber for Azo Dye Degradation

Lanthanum-doped anatase TiO2 coatings, which are composed of assemble crystalline of 50 nm diameter particles, when the percentage of dopant is 0.5 wt%, have been successfully fabricated by solgel dip-coating process on light leakage silica fiber (LSF) which length is 15cm and diameter is 125μm. This was achieved by adjustment of the lanthanum-doped solgel parameters such as molar ratio of precursors in lanthanum-doped TiO2-sols, the ratio of titanium tetrabutoxide to polyvinyl alcohol, dip-coating velocity, drying duration in air, thermal treatment and number of cyclical time of the process. Titania nanocrystals were prepared at ambient temperature in a liquid media using titanium tetrabutoxide as precursor, and the crystallization of amorphous precursor was preceded by peptizing with acid and then refluxing for a periodic time in homothermal water-bath. The photocatalytic properties of the La-TiO2 films had been testified by the photo degradation of methyl orange. The lanthanum-doped anatase TiO2 thin films were characterized by XRD and TEM. The products show much improved photocatalytic activity that will be useful in the design of a novel antibacterial, deodorant and antipollution new photo reactor.

Preparation of Interface-Cross-Linked Micelles as Drug Delivery via RAFT Polymerization

Block copolymer PLA200-b-PPEGMEMA225 were prepared via ring-open polymerization and RAFT process. Further stabilization of the micellar system was performed in water using a dimethacrylate (EDGMA), and the RAFT to cross-link the interface. The interface-cross-linked micelle was found to present better properties than the uncross-linked block copolymer micelle during the drug loading and releasing experiment. Both block copolymers and cross-linked micelles show no toxicity on COS-7 cell line.

Lanthanum-Doped Titania Film Coated on Light Leakage Fiber Photo-Degradation Methyl Orange

Lanthanum-doped anatase TiO2 coatings, which are composed of assemble crystalline of 50 nm diameter particles, when the percentage of dopant is 0.5 wt%, have been successfully fabricated by sol–gel dip-coating process on light leakage silica fiber (LSF) which length is 15cm and diameter is 125μm. This was achieved by adjustment of the lanthanum-doped sol–gel parameters such as molar ratio of precursors in lanthanum-doped TiO2-sols, the ratio of titanium tetrabutoxide to polyvinyl alcohol, dip-coating velocity, drying duration in air, thermal treatment and number of cyclical time of the process. Titania nano crystals were prepared at ambient temperature in a liquid media using titanium tetrabutoxide as precursor, and the crystallization of amorphous precursor was preceded by peptizing with acid and then refluxing for a periodic time in homothermal water-bath. The photocatalytic properties of the La-TiO2 films had been testified by the photo degradation of methyl orange. The lanthanum-doped anatase TiO2 thin films were characterized by XRD and TEM. The products show much improved photocatalytic activity that will be useful in the design of a novel antibacterial, deodorant and antipollution photo reactor.