Grassy Silica Nanoribbons and Strong Blue Luminescence

Abstract

Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications.

Nanodot-to-Rod Transition and Particle Attachment in Self-Organized Polycrystalline Aggregates

“…Within this seaweed zone, we find a slight decrease in fiber width with increasing distances from the front (Figure 6b) and near the sheet center; the texture is very similar to the one in Figure 1c (see Figure S13a for an overview image). While reminiscent of certain microporous silica ribbons, 35 EDX analyses reveal high concentrations of barium (Ba/Si ratios ranging between 3.2 and 4.6), which are values within the typical range for biomorphs. 28 These values also match our analysis of the nanotextured sheet edges near the active growth front (Table S1).…”

Photoluminescence of a Porous Vycor Glass; Surface-Enhanced Photocatalyzed Conversion of CO2 to CH4

“…A variety of porous silicas have been found to be emissive. − Excitation of xerogels derived from the polymerization of tetramethoxysilane/methanol/water (TMOS/CH 3 OH/H 2 O) and tetraethoxysilane/ethanol/water with 200–300 nm light, for example, leads to broad, weak emissions in the 300–450 nm region. − Water is ubiquitous in xerogels and the increase in emission intensity with drying and loss of emissivity on consolidation to a nonporous glass led to the proposal that emissivity derives from silanol groups on the silica surface, or surface states possessing a geometry not typical of glassy silica . Although xerogels are partially polymerized silicas, porous Vycor glass (PVG) derives from a melt heated above its sintering temperature that is acid-leached after cooling. − Nonetheless, UV excitation of PVG also leads to a weak emission in the 400 nm region.…”