Oriented molecular attachments through sol-gel chemistry for synthesis of ultrathin hydrated vanadium pentoxide nanosheets and their applications.

Ultrathin single-crystalline V2 O5 ·0.76H2 O nanosheets with a thickness of 1.5-2.6 nm are prepared on the basis of molecular-level 'oriented attachment' through special sol-gel chemistry. The initial formation of 3-7 nm nanodiscs by confining the condensation reactions within the ab plane is critical to form nanosheets. As a proof-of-concept, these nanosheets exhibit good properties for hydrogen sensors and supercapacitors.

Growth of dandelion-shaped CuInSe2 nanostructures by a two-step solvothermal process.

CuInSe(2) (CIS) nanodandelion structures were synthesized by a two-step solvothermal approach. First, InSe nanodandelions were prepared by reacting In(acac)(3) with trioctylphosphine-selenide (TOP-Se) in 1-octadecene (ODE) at 170 °C in the presence of oleic acid. These InSe dandelions were composed of polycrystalline nanosheets with thickness < 10 nm. The size of the InSe dandelions could be tuned within the range of 300 nm-2 µm by adjusting the amount of oleic acid added during the synthesis. The InSe dandelion structures were then reacted with Cu(acac)(2) in the second-step solvothermal process in ODE to form CIS nanodandelions. The band gap of the CIS dandelions was determined from ultraviolet (UV) absorption measurements to be ∼ 1.36 eV, and this value did not show any obvious change upon varying the size of the CIS dandelions. Brunauer-Emmett-Teller (BET) measurements showed that the specific surface area of these CIS dandelion structures was 44.80 m(2) g(-1), which was more than five times higher than that of the CIS quantum dots (e.g. 8.22 m(2) g(-1)) prepared by using reported protocols. A fast photoresponsive behavior was demonstrated in a photoswitching device using the 200 nm CIS dandelions as the active materials, which suggested their possible application in optoelectronic devices.