Ordered Mesoporous Crystalline Mo-Doped WO₂ Materials with High Tap Density as Anode Material for Lithium Ion Batteries

Highly ordered mesoporous crystalline Mo-doped WO₂ (Mo_<i>x</i>W_1–<i>x</i>O₂: 1 > <i>x</i> > 0.08) materials with different molybdenum contents were synthesized via a nanocasting strategy using mesoporous silica KIT-6 as a hard template. The presence of molybdenum significantly increased the rate of reduction of tungsten trioxide to tungsten dioxide using hydrogen gas as the reducing agent, and it also prevented the dioxide product from being further reduced to zerovalent metal tungsten. This molybdenum doping strategy provides a new solution for the synthesis of WO₂-based materials with well-defined nanostructures. The obtained mesoporous Mo_0.14W_0.86O2 material possessed a metallic conductivity (0.8 Ω cm, 300 K) and a high tap density of 3.6 g cm^–3. This material exhibits a high and reversible lithium storage capacity of 635 mAh g^–1 and is stable up to at least 70 cycles without noticeable fading

Mesoporous Multifunctional Upconversion Luminescent and Magnetic “Nanorattle” Materials for Targeted Chemotherapy

Nanorattles consisting of hydrophilic, rare-earth-doped NaYF₄ shells each containing a loose magnetic nanoparticle were fabricated through an ion-exchange process. The inner magnetic Fe₃O₄ nanoparticles are coated with a SiO₂ layer to avoid iron leaching in acidic biological environments. This multifunctional mesoporous nanostructure with both upconversion luminescent and magnetic properties has excellent water dispersibility and a high drug-loading capacity. The material emits visible luminescence upon NIR excitation and can be directed by an external magnetic field to a specific target, making it an attractive system for a variety of biological applications. Measurements on cells incubated with the nanorattles show them to have low cytotoxicity and excellent cell imaging properties. In vivo experiments yield highly encouraging tumor shrinkage with the antitumor drug doxorubicin (DOX) and significantly enhanced tumor targeting in the presence of an applied magnetic field

Synthesis and Lithium Storage Mechanism of Ultrafine MoO₂ Nanorods

Ultrafine MoO₂ nanorods with a diameter of ∼5 nm were successfully synthesized by a nanocasting method using mesoporous silica SBA-15 as hard template. This material demonstrates high reversible capacity, excellent cycling performance, and good rate capacity as an anode electrode material for Li ion batteries. The significant enhancement in the electrochemical Li storage performance in ultrafine MoO₂ nanorods is attributed to the nanorod structure with small diameter and efficient one-dimensional electron transport pathways. Moreover, density functional theory calculations were performed to elucidate the Li uptake/removal mechanism in the MoO₂ electrodes, which can help us understand the unique cycling behavior of MoO₂ material

Silicon-Based Thermoelectrics Made from a Boron-Doped Silicon Dioxide Nanocomposite

We report a method for preparing p-type silicon germanium bulk alloys directly from a boron-doped silica germania nanocomposite. This is the first successful attempt to produce and characterize the thermoelectric properties of SiGe-based thermoelectric materials prepared at temperatures below the alloy’s melting point through a magnesiothermic reduction of the silica-germania nanocomposite. We observe a thermoelectric power factor that is competitive with the literature record obtained for high energy ball milled nanocomposites. The large grain size in our hot pressed samples limits the thermoelectric figure of merit to 0.5 at 800 °C for an optimally doped Si₈₀Ge₂₀ alloy