A facile and versatile method is reported to fabricate the interwoven tubular hierarchy of SnO2 films using a biotemplate eggshell membrane (ESM) combined sol–gel approach. In order to promote the crystallization of SnO2 films, calcination is necessary and can adjust the size of the building units in the range 2.8–26 nm. Under the direction of ESM biomacromolecules, SnO2 nanocrystallites come into being and assemble into nanotubes, and further pattern porous hierarchical meshworks to faithfully retain the morphology of natural ESM. The sensor performance of as-prepared biomorphic SnO2 was measured for ethanol, liquefied petroleum gas (LPG), H2S, and gasoline. It is found that the SnO2 hierarchical films obtained have a good selectivity for LPG with a working temperature above 300 °C while for ethanol below 270 °C.

Ceria promoted Co@NC (NC, N doped carbon) catalysts are prepared by pyrolysis of biomass materials. Characterization results indicate ceria and Co species facilitate the distribution of each other due to...

Three diverse layers of eggshell membrane (ESM) were introduced in a biogenic sol–gel technique for the synthesis of hierarchical SnO2 nanomaterials with corresponding configurations. Typically, the biomorphic replication of the interwoven inner eggshell membrane was systematically investigated by controlling synthesis conditions such as pH value, dipping time, and calcination temperature. The as‐prepared SnO2 tubes consisting of interconnected 5‐nm nanocrystallite units were successfully interwoven into ESM‐morphic films. Herein, the biomaterial ESM served both as the physical substrate and the functional macromolecule template to realize the precision replication, by the interactions between ESM macromolecules (containing carboxyl, hydroxy, amino groups, etc.) and Sn colloid ingredients. Moreover, some biomacromolecules also acted as the surfactant to yield small‐scaled and well‐distributed SnO2 nanocrystallites based on the strong bondage of short‐chained amino acids within ESM glycoprotein with SnO2 nuclei. This technique can be attributed to a biomimetic sol–gel process and is widely applicable to the synthesis of other functional material systems. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

The bonding and electronic structures of oxygen molecules adsorbed on Al (001) are theoretically investigated from first-principles using the density functional theory within the generalization gradient approximation (GGA) and a supercell approach. The surface is described by means of a 2 X 2 cell with a thickness of fourteen layers, which consist of 9 layers of Al atoms and 5 layers of vacuum. Oxygen molecules are situated on Al surface. The calculated results indicate that oxygen molecules with their axes parallel to the Al surface are the energetically easiest to be adsorbed on Al (001), while those vertical to the Al surface are the most difficult. There are two different processes for the adsorption of oxygen molecules on Al (001), which are O 2 ---+(0 2 )2----+20----+20 2 -and 02---+(02r ---+0 2 -+0, and their occurrences are strongly dependent on the initial morphologies.Oxidation is a ubiquitous phenomenon of nature. The economic loss due to oxidation is very large every year. The investigation of the adsorption of oxygen on the surfaces of metals is of great importance for better understanding of the oxidation mechanism because it is the very beginning stage of oxidation of metals. It is generally believed that the process of O 2 adsorption on metals is in an order of Or-+O---+O----+0 2 -, and the following stages are oxide nucleation, growth and the oxide film formation. As the process of adsorption is too quick to be observed by experiments, a theoretical study may be useful for clarifying the process.Aluminum is one of the richest elements in the earth. It is widely used not only in industry devices but also in everyday life. It is also an important alloying element for making steels and alloys, too. Several works were reported concerning interface phenomena of 01Al [l---9]. Most of them focused on the atomic oxygen adsorption on Al (111). For example, Kiejna et al. [!] investigated the stable adsorption sites for oxygen atoms above or below Al (Ill). Zhukovskii et al. [8] reported the interaction between oxygen and Al (111). Only Krakauer et al.[9] simulated the electronic structures of atomic oxygen on Al (001) using a cluster method. Aluminum is a face centered cubic (FCC) 1768 crystal, and (111) is the closest packed plane, which can form well compatible interface with the plane of a-Ab03 (0001) without interface atomic reconstruction since their symmetry groups are C 3v and D 3h respectively. On the other hand, because the symmetry groups of Al (001) and a-Ab03 (0001) are D 1 4h and D 3h respectively, the formation of the interface of Al (001)la-AI 2 0 3 (0001) involves interface atomic reconstruction. Experimental observations and interpretations of the 01Al (111) interface, therefore, are much easier than those of other interfaces [8]. The transformation processes of O 2 on the Al (001) surfaces were seldom reported. The geometry structures of Al (001) and a-Ab03 are incompatible, and the atomic close packed density of Al (001) is only less than that of Al (111), so 02/Al (001) may be more pop...

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