Porous semiconductor chalcogenide aerogels.
ABSTRACT Chalcogenide aerogels based entirely on semiconducting II-VI or IV-VI frameworks have been prepared from a general strategy that involves oxidative aggregation of metal chalcogenide nanoparticle building blocks followed by supercritical solvent removal. The resultant materials are mesoporous, exhibit high surface areas, can be prepared as monoliths, and demonstrate the characteristic quantum-confined optical properties of their nanoparticle components. These materials can be synthesized from a variety of building blocks by chemical or photochemical oxidation, and the properties can be further tuned by heat treatment. Aerogel formation represents a powerful yet facile method for metal chalcogenide nanoparticle assembly and the creation of mesoporous semiconductors.
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ABSTRACT: We report low cost, high purity shape controlled strategies for the synthesis of mesporous 1D nanostructures owing to their diverse applications in photovoltaics, hydrogen production, and photocatalysis. A novel hydrothermal synthesis method is explored to produce surfactant-free seed mediated mesoporous TiO2 nanowires in grams quantity. The effect of hydrothermal growth time on the evolution of the morphology and structural properties of mesoporous TiO2 nanowires were systematically investigated. FESEM images showed that the diameter of these nanowires is in between 15 and 35 nm, and decreased with the growth time and their length is in few microns. The X-ray diffraction pattern and Raman vibrational spectra of annealed samples were corresponding to the anatase phase. A plausible orientation attachment driven growth was proposed to elucidate the formation mechanism of mesoporous TiO2 nanowires.Ceramics International 04/2015; 41(3):4260-4266. DOI:10.1016/j.ceramint.2014.11.096 · 2.09 Impact Factor
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ABSTRACT: The synthesis of semiconductor nanocrystalline networks using weak capping ligands in aqueous media has been demonstrated. Carbohydrates, including ?-cyclodextrin, D-(+)-glucose, D-glucosamine, lactobionic acid, sucrose, and starch were chosen as weak ligands to facilitate the formation of PbTe nanoparticle networks. The nanoparticle size, ranging from 5 nm to 30 nm, can be tuned by manipulating the temperature and concentration. Through a similar strategy, more complicated nanostructures including carbohydrate spheres@PbTe core-shell structures and Te@carbohydrate@PbTe multilayered submicron cables have been fabricated. This is a general approach which can be easily extended to the fabrication of other semiconductor networks, including PbSe and Bi2Te3 using carbohydrates and ethylenediaminetetraacetic acid (EDTA), respectively, as ligands. KeywordsLead telluride-nanoparticle-network-core shell structures-thermoelectric-carbohydrateNano Research 10/2010; 3(10):685-693. DOI:10.1007/s12274-010-0030-8 · 6.96 Impact Factor
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ABSTRACT: Copper-based monolithic aerogel was prepared by sol–gel method with inorganic salt as precursor, the polyacrylic acid as template and the propylene oxide as gelation agent. The as-prepared aerogel was calcined at 400 °C to remove the organic substances and obtain crystalline copper-oxide nanostructured materials (tenorite, JCPDS File No. 00-045-0937). The aerogels’ structural properties were characterized by the field emission scanning electron microscopy, the high resolution transmission electron microscopy, the X-ray diffraction (XRD), and the Brunauer-Emmett-Teller methods. The results indicate that the as-prepared copper-based aerogel shows a typical three-dimensional porous structure with a large surface areas about 587 m2/g. The XRD patterns show that the as-prepared copper-based aerogel belongs to amorphous materials. The phase transition from the amorphous to crystalline copper oxide occurs at 400 °C.Journal of Sol-Gel Science and Technology 07/2012; 63(1). DOI:10.1007/s10971-012-2777-8 · 1.55 Impact Factor