Hybrid porous magnetic bentonite-chitosan beads for selective removal of radioactive cesium in water.

Porous silicon has found wide applications in many different fields including catalysis and lithium-ion batteries. Three-dimensional hierarchical macro-/mesoporous silicon is synthesized from zero-dimensional Stober silica particles through a facile and scalable magnesiothermic reduction process. By systematic structure characterization of the macro-/mesoporous silicon, a self-templating mechanism governing the formation of the porous silicon is proposed. Applications as lithium-ion battery anode and photocatalytic hydrogen evolution catalyst are demonstrated. It is found that the macro-/mesoporous silicon shows significantly improved cyclic and rate performance over the commercial nanosized and micrometer-sized silicon particles. After 300 cycles at 0.2 A g–1, the reversible specific capacity is still retained as much as 959 mAh g–1 with a high mass loading density of 1.4 mg cm–2. With the large current density of 2 A g–1, a reversible capacity of 632 mAh g–1 is exhibited. The coexistence of both macro- ...

Self-Templating Construction of 3D Hierarchical Macro-/Mesoporous Silicon from 0D Silica Nanoparticles

This work investigated the thermoelectric properties of thin silicon membranes that have been decorated with high density of nanoscopic holes. These ?holey silicon? (HS) structures were fabricated by either nanosphere or block-copolymer lithography, both of which are scalable for practical device application. By reducing the pitch of the hexagonal holey pattern down to 55 nm with 35percent porosity, the thermal conductivity of HS is consistently reduced by 2 orders of magnitude and approaches the amorphous limit. With a ZT value of 0.4 at room temperature, the thermoelectric performance of HS is comparable with the best value recorded in silicon nanowire system.

Holey Silicon as an Efficient Thermoelectric Material

Silicon is regarded as one of the most promising next generation lithium-ion battery anodes due to its exceptional theoretical capacity, appropriate voltage profile, and vast abundance. Nevertheles...

Rational Design and Mechanical Understanding of Three-Dimensional Macro-/Mesoporous Silicon Lithium-Ion Battery Anodes with a Tunable Pore Size and Wall Thickness.

SiO2 amorphous nanopowder (NP) is produced with the specific surface area of 154 m2/g by means of evaporation by a pulsed electron beam aimed at Aerosil 90 pyrogenic amorphous NP (90 m2/g) as a target. SiO2 NP nanoparticles showed improved magnetic, thermal, and optical properties in comparison to Aerosil 90 NP. Possible reasons of emergence of d0 ferromagnetism at the room temperature in SiO2 amorphous NP are discussed. Photoluminescent and cathode luminescent properties of the SiO2 NP were investigated.

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Properties of Silicon Dioxide Amorphous Nanopowder Produced by Pulsed Electron Beam Evaporation

A new hole-bridge structure based on a SiO2 nanoarray and its ferromagnetism

A detailed study of a new method for preparing ordered porous silicon (PS) is reported. An Ag@SiO2 two-dimensional template was caused to self-assemble on a silicon surface using the vertical deposition method. Ordered PS was obtained by electrodeless etching of the Si wafer plus template in a mixed solution of HF and H2O2. The ordered PS was characterized using Field Emission Scanning Electron Microscopy, Spectrofluorimetry and Fourier Transform Infrared Absorption Spectroscopy. The diameter of the nanopores is about 500 nm. And the thermal conductivities of the ordered PS were found to be reduced compared to bulk silicon and disordered PS, due to enhanced phonon scattering. Compared with disordered PS, the ordered PS has a lower specific surface area. Straight holes and columnar structure in the ordered PS result in high absorption when the wavelength is longer than 890 nm and a high transmittance in the test range of 400–4000 wavenumbers.

A template-based method for preparing ordered porous silicon

A new method for fabricating ordered porous silicon is reported. A two-dimensional silica nanosphere array is used as a template with a hydrofluoric acid–hydrogen peroxide solution for etching the nanospheres. The initial diameter and distribution of the holes in the resulting porous silicon layer are determined by the size and distribution of the silica nanospheres. The corrosion time can be used to control the depths of the holes. It is found that the presence of a SiO2 layer, formed by the oxidation of the rough internal surface of the hole, is the primary reason allowing the corrosion to proceed. Ultraviolet reflection and thermal conductivity measurements show that the diameter and distribution of the holes have a great influence on properties of the porous silicon.

http://iopscience.iop.org/article/10.1088/0256-307X/33/5/058103/pdf

Xiao-Wei Liu

Papers

A new hole-bridge structure based on a SiO2 nanoarray and its ferromagnetism

A template-based method for preparing ordered porous silicon

A Method for Preparation of Ordered Porous Silicon Based on a 2D SiO 2 Template