Silicon nanowires with permanent electrostatic charges for nanogenerators.

Electrets are dielectric materials possessing a quasi-permanent electric charge or dipole polarization. Frequently, the electrets are adversely affected by environmental temperature and humidity, leading to charge instability, which severely restricts applications. Here we show that silicon nanowires (SiNWs) via modified oxide-assisted growth can surprisingly serve as electrets with permanent electrostatic charges and surface potential up to 7.7 mV. Significantly, the extraordinary electret behavior of SiNWs is extremely robust, remaining stable against immersion in water for over 2 months. The SiNWs were utilized to fabricate a nanogenerator, which yielded an output electrical power of 2.19 × 10(-11) W with a conversion efficiency of 2.2%. The nanogenerator consists of only one movable part, giving highly sustainable and stable output signals, and thus holds promise for various self-powered applications. The permanent electrostatic charges on SiNWs are attributed to the formation of α-quartz in SiNWs.

Heteropolyacid-assisted fabrication of carbon nanostructures under ambient conditions.

Under ambient conditions, H(3)PW(12)O(40)-assisted electrochemical reduction process for chemical synthesis of SWNT-CNS, and H(3)PMo(12)O(40)-assisted ball milling process for COS fabrication.

An ultrasensitive method: surface-enhanced Raman scattering of Ag nanoparticles from beta-silver vanadate and copper.

Ultrasensitive surface-enhanced Raman scattering signals of four typical analytes were observed on Ag nanoparticles from beta-silver vanadate and copper, even though the concentrations of these analytes were as low as 1 x 10(-16) M (Rhodamine 6G or crystal violet) and 1 x 10(-15) M (trinitrotoluene or bovine serum albumin).

Metal (Cu, Au)-modified silicon nanowires for high-selectivity solvent-free hydrocarbon oxidation in air.

Metal (Au, Cu)-modified Si nanowires (SiNWs) are superior catalysts for selective oxidation of hydrocarbons, while SiNWs are a powerful substrate support (enhance efficiency and selectivity) for nanocatalysts.

Scanning tunneling microscope excited cathodoluminescence from ZnS nanowires.

The electronic excitation spectrum of ZnS nanowires (NWs) is characterized by cathodoluminescence (CL) excited using the tip of a scanning tunneling microscope as a highly localized and bright source of low-energy (150-350 eV) electrons with impinging power densities in the range of up to 60 kW/cm(2) or more. The CL spectra reveal significant differences when compared with the photoluminescence spectra of ZnS NWs. The differences can be associated with the properties of the surface region of the NWs, which are preferentially emphasized in the CL spectra owing to the small probing depth of low-energy electrons.