Nanostructured materials from precursors

The ideal control on the structural and textural properties of perovskite-type oxides can be better achieved by exploiting aerosol spray synthesis methods to prepare highly dispersed and nanostructured materials from metal salt precursors. High-specific-surface-area (above 20m /g) crystalline perovskite-type oxides can be then obtained, which are suitable for a variety of applications. A major advantage of spray methods is that the material is directiy processed from the precursor solution with a reduced number of processing steps during powder synthesis (one-step approach), thus making them ideally suited for... 

Equation 3.1 and Equation 3.2) (including the mean particle sizes obtained) (Adapted from Bonnemann, H. and Brijoux, W., in Surfactant-Stabilized Nanosized Colloidal Metals and Alloys as Catalyst Precursors/Advanced Catalysts and Nanostructured Materials, Moser, W., Ed., Academic Press, San Diego, 1996, pp. 165-196, Chap. 7. With permission from Elsevier Science.)... 

Figure 5.3.9 (A) Simplified geometric model [46, 89] for the preparation of industrial Cu/ZnO catalysts comprising subsequent meso- and nanostructuring of the material from [56], In a first micro structure directing step (mesostructuring), the Cu,Zn coprecipitate crystallizes in the form of thin needles of the zincian malachite precursor, (Cu,Zn)2(0H)C03. In a second step, the individual needles are decomposed and demix into CuO and ZnO. The effectiveness of this nanostructuring step depends critically on a high Zn content in the precursor, which in zincian malachite is limited to Cu Zn ca. 70 30 due to solid-state chemical constraints [75]. Finally, interdispersed CuO/ZnO is reduced to yield active Cu/ZnO. (B) Chemical memory Dependence of catalytic activity in methanol synthesis on the conditions of the coprecipitation and aging steps, from [85].

According to Kavan (1997), electrochemical carbons are synthetic solids consisting mainly of atoms of elemental carbon, which can be prepared electrochemically from suitable precursors. Electrochemical carbonization is characterized by three specific features (Kavan et al., 2004) (1) ability to obtain relatively unstable carbon chains (2) easy templating of carbon nanostructured materials by the precursors and (3) defined kinetics of certain reactions, allowing for the control of film thickness. 

Lastly, it is possible to decorate and elaborate nanowires using SCFs, for example by hydrogen reduction of metal precursors in SCCO2 [59]. Cu and Pd nanocrystals were deposited from different types of nanostructured materials including nanocrystal-nanowire, spherical aggregation-nanowire, shell-nanowire composites, and mesoporous metals supported by the framework of nanowires [59]. 

Hoheisel TN, Schrettl S, SziUuweit R, Frauenrath H (2010) Nanostructured carbonaceous materials from molecular precursors. Angew Chem Int Ed 49 6496-6515... 

Chemistry plays an important role in the fabrications of new functional materials with desired properties from conceptual point of view via tuning of microstructural properties. The synthetic approach of functional Inorganic nanomaterials with their novel properties and with their applications is a powerful driving force for the scientists in materials science. The synthesis of single source precursor was carried out based on molecular structure design concept (MSDC) for the stabilization via transformation into a solid crystalline nanostructure material with improved structural and properties. Single source precursor is a molecular entity which contains all the necessary elements of a final product in a well-defined structural formula [36-42]. It is of three types as shown below ... 

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