Mesoporous Anatase TiO 2 Nanorods as Thermally Robust Anode Materials for Li‐Ion Batteries: Detailed Insight into the Formation Mechanism

Titanium dioxide-based anode materials for lithium-ion batteries: structure and synthesis

Lithium-ion batteries (LIBs) have high energy density, long life, good safety, and environmental friendliness, and have been widely used in large-scale energy storage and mobile electronic devices. As a cheap and non-toxic anode material for LIBs, titanium dioxide (TiO₂) has a good application prospect. However, its poor electrical conductivity leads to unsatisfactory electrochemical performance, which limits its large-scale application. In this review, the structure of three TiO₂ polymorphs which are widely investigated are briefly described, then the preparation and electrochemical performance of TiO₂ with different morphologies, such as nanoparticles, nanowires, nanotubes, and nanospheres, and the related research on the TiO₂ composite materials with carbon, silicon, and metal materials are discussed. Finally, the development trend of TiO₂-based anode materials for LIBs has been briefly prospected.

Single-Source Alkoxide Precursor Approach to Titanium Molybdate, TiMoO5, and Its Structure, Electrochemical Properties, and Potential as an Anode Material for Alkali Metal Ion Batteries

Transition-metal oxide nanostructured materials are potentially attractive alternatives as anodes for Li ion batteries and as photocatalysts. Combining the structural and thermal stability of titanium oxides with the relatively high oxidation potential and charge capacity of molybdenum(VI) oxides was the motivation for a search for approaches to mixed oxides of these two metals. Challenges in traditional synthetic methods for such materials made development of a soft chemistry single-source precursor pathway our priority. A series of bimetallic Ti-Mo alkoxides were produced by reactions of homometallic species in a 1:1 ratio. Thermal solution reduction with subsequent reoxidation by dry air offered in minor yields Ti₂Mo₂O₄(OMe)₆(OⁱPr)₆ (1) by the interaction of Ti(OⁱPr)₄ with MoO(OMe)₄ and Ti₆Mo₆O₂₂(OⁱPr)₁₆(iPrOH)₂ (2) by the reaction of Ti(OⁱPr)₄ with MoO(OⁱPr)₄. An attempt to improve the yield of 2 by microhydrolysis, using the addition of stoichiometric amounts of water, resulted in the formation with high yield of a different complex, Mo₇Ti_7+xO_31+x(OⁱPr)_8+2x (3). Controlled thermal decomposition of 1–3 in air resulted in their transformation into the phase TiMoO₅ (4) with an orthorhombic structure in space group Pnma, as determined by a Rietveld refinement. The electrochemical characteristics of 4 and its chemical transformation on Li insertion were investigated, showing its potential as a promising anode material for Li ion batteries for the first time. A lower charge capacity and lower stability were observed for its application as an anode for a Na ion battery.

Controlled decomposition of a structurally characterized Ti-Mo oxo-alkoxide precursor offered an approach to the new ternary oxide TiMoO₅, showing promising characteristics as an anode material for Li ion batteries.

TiO₂ Nanobelt@Co₉S₈ Composites as Promising Anode Materials for Lithium and Sodium Ion Batteries

TiO₂ anodes have attracted great attention due to their good cycling stability for lithium ion batteries and sodium ion batteries (LIBs and SIBs). Unfortunately, the low specific capacity and poor conductivity limit their practical application. The mixed phase TiO₂ nanobelt (anatase and TiO₂-B) based Co₉S₈ composites have been synthesized via the solvothermal reaction and subsequent calcination. During the formation process of hierarchical composites, glucose between TiO₂ nanobelts and Co₉S₈ serves as a linker to increase the nucleation and growth of sulfides on the surface of TiO₂ nanobelts. As anode materials for LIBs and SIBs, the composites combine the advantages of TiO₂ nanobelts with those of Co₉S₈ nanomaterials. The reversible specific capacity of TiO₂ nanobelt@Co₉S₈ composites is up to 889 and 387 mAh·g⁻¹ at 0.1 A·g⁻¹ after 100 cycles, respectively. The cooperation of excellent cycling stability of TiO₂ nanobelts and high capacities of Co₉S₈ nanoparticles leads to the good electrochemical performances of TiO₂ nanobelt@Co₉S₈ composites.

General facile approach to transition-metal oxides with highly uniform mesoporosity and their application as adsorbents for heavy-metal-ion sequestration

Mesoporous powders of transition-metal oxides, TiO2, ZrO2, HfO2, Nb2O5, and Ta2O5, pure from organic impurities were produced by a rapid single-step thermohydrolytic approach. The obtained materials display an impressively large active surface area and sharp pore-size distribution, being composed of partially coalesced uniform nanoparticles with crystalline cores and amorphous shells. They reveal extremely high adsorption capacity in removal of Cr(VI) anions from solutions (25.8 for TiO2, 73.0 for ZrO2, and 74.7 mg g(-1) for Nb2O5 in relation to the Cr2O7(2-) anion), making them very attractive as adsorbents in water remediation applications. The difference in adsorption capacities for the studied oxides may be explained by variation in surface hydration and surface-charge distribution.

Precursor directed synthesis--"molecular" mechanisms in the Soft Chemistry approaches and their use for template-free synthesis of metal, metal oxide and metal chalcogenide nanoparticles and nanostructures

This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials.