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    Silica-supported nanostructured copper phyllosilicate: Boosting stability, capacity, and conductivity of Li-ion battery Si-based anodes
    (2026-11-01)
    Shajan, Minnu Gemini
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    Chou, Feng Yuan
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    Prasanseang, Warot
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    Yimtrakarn, Trakarn
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    Sooknoi, Tawan
    Explosive demand for large-scale rechargeable batteries has driven the search for alternative electrode materials with higher energy density, lower toxicity, lower cost, and more natural abundance. Si-based materials, e.g., Si, SiO, SiO<inf>2</inf>, and silicates have emerged as promising choices, with extremely high capacities from most cost-effective and abundant sources. However, these compounds still suffer from major issues, such as extreme volume change, poor cycling stability, high manufacturing costs, and low conductivity. Herein, we have prepared low-cost porous nanosized silica-supported copper phyllosilicate, x CuPS/SiO<inf>2</inf>, with different Cu loadings and investigated them as anode material in Li cells. Due to the highly dispersed Cu species strongly interacted with nanosphere SiO<inf>2</inf> support matrix, 20CuPS/SiO<inf>2</inf> has been found to deliver a capacity as high as ∼3550 mAh g<sup>‒1</sup> at 500 mA g<sup>‒1</sup> with an impressive capacity retention of 99% upon conversion reactions with Li<sup>+</sup>, and a reversible capacity of 2216 mAh g<sup>‒1</sup> at 5000 mA g<sup>‒1</sup>. These values are among the highest ever reported for Si-, silicate-, silica-, and copper oxide-based anodes. Various phases, i.e., CuO, Li<inf>4</inf>SiO<inf>4</inf>, SiO, Si, Li<inf>2</inf>O, Cu, and Li<inf>x</inf>Si, are formed in the SiO<inf>2</inf> nanodomain, as confirmed by various ex situ characterization techniques, and the redox mechanism has been proposed. The components, particularly Li<inf>4</inf>SiO<inf>4</inf>, Li<inf>2</inf>O, and SiO<inf>2</inf>, are shown to help buffer volumetric or structural changes induced by the redox processes. The nanosized composite and the in situ -formed metallic Cu play a crucial role in rapid charge-transfer kinetics. These synergistic effects ultimately result in an unprecedented electrochemical performance of x CuPS/SiO<inf>2</inf> observed in this work.
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    Selective acetylene removal from ethylene-rich feed by cross-metathesis over supported WO3 catalysts
    (2023-01-25)
    Promchana, Pratya
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    Choojun, Kittisak
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    Limphirat, Wanwisa
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    Poo-arporn, Yingyot
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    Sooknoi, Tawan
    Acetylene in ethylene-rich feed can be removed via acetylene/ethylene cross-metathesis over WO<inf>3</inf>-supported catalysts at 450 °C, yielding 1,3-butadiene with cyclohexene as a minor product. The catalyst must be treated with ethylene at 600 °C to generate a genuinely active site of tungsten (IV) alkylidene species (W=CH<inf>2</inf>). The H<inf>2</inf> treatment decreases surface W[dbnd]O concentration, and hence the activity. Raman spectroscopy shows that active single-site WO<inf>3</inf> species, including mono oxo-WO<inf>3</inf> ((O=)W(O-Si)<inf>3</inf> and (O=)W(O-Si)<inf>4</inf>) and dioxo-WO<inf>3</inf> species (O=)<inf>2</inf>W(O-Si)<inf>2</inf>) were generated in 2%WO<inf>3</inf>/SiO<inf>2</inf>, while the WO<inf>3</inf> cluster and bulk WO<inf>3</inf> exist in 3–5%WO<inf>3</inf>/SiO<inf>2</inf> and 7%WO<inf>3</inf>/SiO<inf>2</inf>, respectively. The 5%WO<inf>3</inf>/NaX and 5%WO<inf>3</inf>/NaY provide lower activity due to coke formation over the acid sites. With high surface area and confined surface silanol of 5%WO<inf>3</inf>/MCM-41% and 5%WO<inf>3</inf>/SBA-15, in situ TR-EXAFS evidences the formation of only O[dbnd]W(O-Si)<inf>3</inf>. This species provides an isolated W=CH<inf>2</inf> site with relatively higher activity and is less prone to coke formation than the WO<inf>3</inf> cluster in 5%WO<inf>3</inf>/SiO<inf>2</inf>.
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    Semi-micro preparation and characterization of bonded phase ODS-silica prepared from rice husk silica
    (2006-04-01)
    Burns, Duncan Thorburn
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    Tungkananurak, Kanita
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    Jadsadapattarakul, Damrongsak
    Bonded phase ODS-silica has been prepared using purified silica prepared from rice husk by burning, reflux with sodium hydroxide solution and precipitation as a gel. The gel was spray dried, further purified by washing with concentrated hydrochloric acid then distilled water prior to vacuum drying and silanization and end-capping. The product's physical and chromatographic properties are reported. © Springer-Verlag 2006.