Mesoporous and mesostructured TiO2 coatings for photocatalytic applications

The correlation between the textural properties and the photocatalytic activity of nanocrystalline Titanium dioxide (TiO₂)-anatase films obtained by sol–gel has been investigated. Mesoporous and mesostructured TiO₂-anatase films were prepared using different titanium precursors and Pluronic (F127) and polyethylene glycol hexadecyl ether P5884 (Brij58) surfactants via acid catalysis. Ca(NO₃)₂ and WCl₆ were incorporated to TiO₂ sols to investigate the effect of the doping on the photocatalytic behaviour. The microstructure and textural properties were characterised by X-ray diffraction, spectral ellipsometry and transmission electronic microscopy. The photocatalytic properties were evaluated in aqueous solution (methyl orange) and in gas phase (trichloroethylene, sulphide acid and methyl-ethyl-ketone) using multilayer films deposited on glass-slides. TiO₂-B-Brij-58 films exhibited the most efficient photocatalytic activity either in aqueous or gas medium. The Ca doping strongly enhances the photocatalytic activity associated with the reduced recombination of electrons and holes in the catalyst.     

Mesoporous electrode material from alumina-stabilized anatase TiO2 for lithium ion batteries

A mesoporous electrode material whose structure is composed of anatase nanocrystals stabilized by alumina is reported. Powder X-ray diffraction shows the anatase phase only, but micro-Raman spectroscopy shows that the materials have a core-shell morphology with grains of bulk anatase covered by a thin rutile layer on the surface. This structure is unique when compared to analogous materials stabilized by zirconia (PNNL-1). Nitrogen adsorption isotherms demonstrate a monotonous increase in surface area and mesopore volume with increasing Al content. Thin film electrodes from these materials were characterized by lithium insertion electrochemistry. Cyclic voltammograms exhibit significant differences in Li accommodation in Al-free and Al-stabilized materials.     

介孔TiO_2载体对固体聚合物电解质水电解阳极催化剂性能的影响

以钛酸四丁酯为原料,采用溶剂蒸发自组装法(EISA)在不同焙烧温度下制备不同比表面积及结构的介孔TiO_2载体.利用亚当斯熔融法在介孔TiO_2载体表面负载IrO_2纳米颗粒,对IrO_2/TiO_2的结构和性能进行了表征,并在质子交换膜(PEM)单电池中对IrO_2/TiO_2催化剂进行了电化学表征.结果表明,随着焙烧温度的升高,TiO_2载体比表面积降低,孔径增大,孔容减小,组织结构有利于向金红石相转变.TiO_2载体的存在明显改善了IrO_2颗粒的分布,IrO_2晶粒尺寸减小.在IrO_2负载量(质量分数)为40%的情况下,IrO_2颗粒易在低比表面积的载体表面形成连续的IrO_2导电催化层,载体比表面积越低其催化活性越高.在1A/cm~2的电流密度下,IrO_2,40%IrO_2/TiO_2-2和40%IrO_2/TiO_2-3催化剂的极化电势分别为2.028,2.426和2.064 V.介孔TiO_2载体的表面结构及导电性极大影响了催化剂的电化学活性.     

Continuous supercritical hydrothermal synthesis: lithium secondary ion battery applications

Nanosized lithium iron phosphate (LiFePO₄) and transition metal oxide (MO, where M is Cu, Ni, Mn, Co, and Fe) particles are synthesized continuously in supercritical water at 25?C30?MPa and 400??C under various conditions for active material application in lithium secondary ion batteries. The properties of the nanoparticles, including crystallinity, particle size, surface area, and electrochemical performance, are characterized in detail. The discharge capacity of LiFePO₄ was enhanced up to 140?mAh/g using a simple carbon coating method. The LiFePO₄ particles prepared using supercritical hydrothermal synthesis (SHS) deliver the reversible and stable capacity at a current density of 0.1?C rate during ten cycles. The initial discharge capacity of the MO is in the range of 800?C1,100?mAh/g, values much higher than that of graphite. However, rapid capacity fading is observed after the first few cycles. The continuous SHS can be a promising method to produce nanosized cathode and anode materials.     

A high performance carrier for SnO2 nanoparticles used in lithium ion battery

Ferrocene-encapsulated single-walled carbon nanotubes (Fc@SWNTs) are developed as carriers for attaching SnO(2). When Fc@SWNTs coated with SnO(2) nanoparticles were used as anode material in lithium ion batteries, the reversible capacity remained over 900 mA h g(-1) after 40 cycles, much higher than other carbon nanomaterials.     

Preparation and electrochemical properties of Ag-modified TiO2 nanotube anode material for lithium–ion battery

TiO₂ nanotubes prepared by using a hydrothermal process were firstly coated with silver nanoparticles as the anode materials for lithium–ion batteries by the traditional silver mirror reaction. The physical properties of the as-synthesized samples were investigated by X-ray diffraction and transmission electron microscopic. The as-prepared samples were used as negative materials for lithium–ion battery, whose charge–discharge properties, cyclic voltammetry, electrochemical impedance spectroscopy and cycle performance were examined in detail. The results showed that the Ag additive decreased the polarization of anode, and marvelously improved the high-rate discharge capacity and cycling stability of TiO₂ nanotubes.     

One-pot hydrothermal synthesis of porous anatase TiO2 nanotube formed bundles for lithium ion battery anodes

Anatase phase of TiO₂ nanomaterial has been deemed a potential anode material for lithium ion battery (LIB) applications because of its remarkable electrochemical properties. However, TiO₂ anodes always suffer from intrinsic poor electrical conductivity and slow ion kinetics, which would restrict their practical usage. To address this issue, efficient control and design of the anatase crystal structure of TiO₂ material with desirable morphology is one of the critical approaches. In this work, a good lithium storage capability of 181 mA hr g⁻¹ at rate of 0.2C, high rate performance of 70 mA hr g⁻¹ at 20C, and excellent cyclability of 117 mA hr g⁻¹ with a capacity retention of 93% at 1C after 100 cycles and 84 mA hr g⁻¹ at 10C after 1,000 cycles are observed in an optimized porous anatase TiO₂ one-dimensional nanotube bundle nanomaterial fabricated through a simple hydrothermal process with post calcination treatment. These excellent electrochemical properties of the product can be ascribed to its anatase crystal phase, 1D nanostructure, and porous framework with a large surface area, which provide it with an efficient electrode/electrolyte contact area and a faster ion/electron diffusion pathway.     

Improved electrochemical properties of Sn-doped TiO2 nanotube as an anode material for lithium ion battery

Anatase TiO₂ nanotube was doped with different contents of Sn (3, 5, and 7 at.%) through sol-gel method and subsequent hydrothermal process. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET), and Hall effect measurement are utilized to characterize the structures, components, chemical environments, morphologies, specific areas, and electronic conductivities of the samples. The investigation in cycling performances demonstrates that 5 at.% Sn-doped TiO₂ nanotube exhibits the best cycling stability, with specific capacity of 386 mAh g^?1 and coulombic efficiency of 99.2 % after 50 cycles at 0.1 C, much higher than those of the other Sn-doped samples and pristine TiO₂ nanotube. The improved electrochemical performances of Sn-doped TiO₂ nanotube are attributed to the increase of electronic conductivity and therefore enhance the reversible capacity of the material.     

Synthesis and electrochemical study of Li-Mn-Ni-O cathodes for lithium battery applications

Cathode powders of the Li–Mn–Ni–O system have been prepared at a Mn/(Mn+Ni) ratio varying from 0 to 1. The solid state reaction method was used to obtain the cathode materials by mixing MnO₂, LiCO₃ and NiO. A 20% excess of lithium was used in the precursors. The materials produced were examined by X-rays to identify their structure. Batteries were assembled by using these materials as cathode with a liquid electrolyte consisting of EC/DC 1:1, 1 LiPF₆ and Li anode. Their capacity, cycle fading and charge-discharge conditions were evaluated.Presented at the 3rd International Meeting "Advanced Batteries and Accumulators", June 16th–June 20th 2002, Brno, Czech Republic     

高压锂离子电池电解液的研究进展

电极/电解液界面不稳定是高压锂离子电池发展的主要瓶颈.提高界面稳定性是高压锂离子电池得以应用的前提.本文综述了碳酸酯基电解液氧化分解反应机理、新型耐高压溶剂体系和新型成膜添加剂实验与理论的研究进展.     

Novel porous anatase TiO2 nanorods and their high lithium electroactivity

We demonstrated a simple approach for the synthesis of a kind of novel porous anatase TiO₂ nanorods. The method is based on a reaction in composite-hydroxide eutectic system and normal atmosphere without using an organic dispersant or capping agent. The synthesis technique is cost effective, easy to control and is adaptable to mass production. This is the first time TiO₂ nanorods with a porous structure are fabricated by using this method. The as-prepared material was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), nitrogen adsorption and desorption experiments and electrochemical measurements. The results showed that the anatase TiO₂ nanorods obtained in our experiment have a large specific surface area with a porous structure which makes it have a potential application in catalysts and battery materials, especially in lithium ion batteries. In this study, we mainly tested their electrochemical performance as negative materials for lithium ion batteries. Further research to optimize synthesis conditions, particularly to develop their application in the field of catalysis is currently in progress.     

Synthesis and electrochemical properties of PbLi2Ti6O14 for lithium ion battery applications

Journal of Solid State Electrochemistry - Lead lithium titanium oxide with the composition PbLi2Ti6O14 has been successfully synthesized by the rheological phase reaction method and exhibited...     

Mesoporous Foam TiO2 Nanomaterials for Effective Hydrogen Production

Hydrolysis of TiCl₄ in a diether‐functionalized imidazolium ionic liquid (IL), namely 1‐methyl‐3‐[2‐(2‐methoxy(ethoxy)ethyl]imidazolium methane sulfonate (M(MEE)I ? CH₃SO₃), results in a heterostructured organic/inorganic and sponge‐like porous TiO₂ material. The thermal treatment (300 °C) followed by calcination (500 °C) affords highly porous TiO₂. The characterization of the obtained samples (with and without IL, before and after calcination) by XRD, SEM, and TEM reveals TiO₂ anatase crystalline phases and irregular‐shaped particles with different porous structures. These hierarchical‐structured mesoporous TiO₂ nanomaterials were employed as efficient photocatalysts in the water‐splitting process, yielding up to 1304 μmol g^?1 on hydrogen production.     

Mesoporous Anatase TiO2 Nanorods as Thermally Robust Anode Materials for Li‐Ion Batteries: Detailed Insight into the Formation Mechanism

Uniformly mesoporous and thermally robust anatase nanorods were produced with quantitative yield by a simple and efficient one‐step approach. The mechanism of this process was revealed by insertion of Eu³⁺ cations from the reaction medium as luminescent probes. The obtained structure displays an unusually high porosity, an active surface area of about 300 m²g^?1 and a specific capacity of 167 mA h g^?1 at a C/3 rate, making it attractive as an anode electrode for Li‐ion batteries. An additional attractive feature is its remarkable thermal stability; heating to 400 °C results in a decrease in the active surface area to a still relatively high value of 110 m² g^?1 with conservation of open mesoporosity. Thermal treatment at 800 °C or higher, however, causes transformation into a non‐porous rutile monolith, as commonly observed with nanoscale titania.     

SnS2/graphene nanocomposite: A high rate anode material for lithium ion battery

In this work,via a facile solvothermal route,we synthesized an anode material for lithium ion batteries(LIBs)—SnS_2 nanoparticle/graphene(SnS_2 NP/GNs) nanocomposite.The nanocomposite consists of SnS_2nanoparticles with an average diameter of 4 nm and graphene nanosheets without restacking.The SnS_2 nanoparticles are firmly anchored on the graphene nanosheets.As an anode material for LIBs,the nanocomposite exhibits good Li storage performance especially high rate performance.At the high current rate of 5,10,and 20 A/g,the nanocomposite delivered high capacities of 525,443,and 378 mAh/g,respectively.The good conductivity of the graphene nanosheets and the small particle size of SnS_2contribute to the electrochemical performance of SnS_2 NP/GNs.     

Electrolytic synthesis of FeS2 for thin-layer lithium battery

Purposeful synthesis of iron sulfide FeS₂ films for a lithium battery were purposefully synthesized on a 18N12Kh9T steel cathode from a solution containing Mohr’s salt and Na₂S₂O₃. Various aspects of synthesis were studied. Thin-film Fe-sulfide synthesis products were tested in a prototype lithium battery and also in a lithium-ion system. The synthesized electrolytic iron sulfide FeS₂ with a marcasite structure is capable of reversible electrochemical transformation with output of 390 mA h g^?1 in negative electrodes of the lithium-ion system with a LiMn₂O₄ counter electrode.     

New carbon-rich materials for electronics, lithium battery, and hydrogen storage applications

Methods for the preparation of novel carbon-rich materials for use in electronic devices, lithium batteries or possible hydrogen storage applications are presented.     

A new promising high temperature lithium battery solid electrolyte

Lithium lanthanoid silicates find importance as a solid electrolyte in high temperature lithium batteries in view of its high ionic conductivity at high temperatures. An first ever attempt is made to synthesis a new high temperature solid electrolyte viz., lithium samarium holmium silicate by sol–gel process and it has been characterized by thermal analysis (TGA–DTA), X-ray diffraction (XRD), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Lithium ion conductivity of 0.8087 × 10⁻⁷ Ω⁻¹ cm⁻¹ at 25 °C was obtained and it increases with increasing temperature. For the first time a highest conductivity of 0.1095 × 10⁻² Ω⁻¹ cm⁻¹ was obtained at 850 °C which is high compared to other high temperature lithium battery solid electrolytes.     

中孔TiO2的制备与表征

以聚氧乙烯十二烷基醚为模板剂,钛酸四丁酯为钛源制备了中孔TiO2,探讨了焙烧温度和掺杂对中孔TiO2结构的影响。利用XRD,TEM,FT-IR和N2吸附等对其结构进行了表征。结果表明,中孔TiO2具有较大的孔径和较高的热稳定性;钇掺杂使中孔TiO2的比表面积和孔体积增大及热稳定性提高。以噻吩加氢脱硫为探针反应,考察了以中孔TiO2为载体的Ni基催化剂的催化活性,钇掺杂能提高其催化活性。