نتایج جستجو برای: oxides
تعداد نتایج: 21448 فیلتر نتایج به سال:
Iron oxides play an increasingly prominent role in heterogeneous catalysis, hydrogen production, spintronics, and drug delivery. The surface or material interface can be performance-limiting in these applications, so it is vital to determine accurate atomic-scale structures for iron oxides and understand why they form. Using a combination of quantitative low-energy electron diffraction, scannin...
This review focuses on electron transfer at the interfaces between metal oxides and dye molecules within the context of the chemical nature of the anchoring functional groups, the structure of the dye molecules and the morphology of the metal oxides. In dye-sensitized metal oxides, the efficiency of interfacial charge separation and hence photon-to-current conversion may be sensitively manipula...
In several cases ethylenediaminetetraacetic acid (EDTA) proved to be an efficient mobilising amendment during chemically enhanced phytoextraction of heavy metals. The presence of Fe-(hydr)oxides and their dissolution after the addition of EDTA can limit the phytoextraction of the targeted heavy metals due to the high stability of the formed Fe(III)EDTA complexes. This study has focused on the i...
In this article, passivated Pb-Sn and Pb-Sb alloys with different compositions were studied by X-ray photoelectron spectroscopy (XPS). The passive films were found to have a double-layer structure. Both Sn and Sb were found to play an important role during the growth of passive film, which resulted in different compositions of passive filJ;l1s. The Pb oxides, Pb sulfate, SnlSb oxides, and Pb-Sn...
A simple and general procedure has been developed for the syntheses of ordered largepore (up to 14 nm) mesoporous metal oxides, including TiO2, ZrO2, Nb2O5, Ta2O5, Al2O3, SiO2, SnO2, WO3, HfO2, and mixed oxides SiAlOy, Al2TiOy, ZrTiOy, SiTiOy, ZrW2Oy. Amphiphilic poly(alkylene oxide) block copolymers were used as structure-directing agents in nonaqueous solutions for organizing the network-form...
1-(Diphenylphosphoryl)alka-1,2-dienes (phosphonoallenes) in Brønsted (super)acids (TfOH, FSO3H, and H2SO4) at -70 to 120 °C for 30 min to 4 h gave, at first, (3-hydroxyalk-1-en-1-yl)diphenylphosphine oxides, as kinetically favorable reaction products, that are further converted into 1-phenyl-1,4-dihydrophosphinoline 1-oxides as thermodynamically stable compounds. The latter compounds are formed...
While most of crystalline wide gap oxides are both stoichiometric and insulating, a handful of them including ZnO and In2O3 are naturally anion-deficient and electron conductors. Even fewer of the oxides are naturally cation-deficient and hole conductors, the arch-type of which is Cu2O. Based on first principles calculation of equilibrium nonstoichiometry and defect stability, we explain why th...
In this paper, cupric oxides was found to effectively oxidize levulinic acid (LA) and lead to the decarboxylation of levulinic acid to 2-butanone. The effects of cupric oxide dosage, reaction time and initial pH value were investigated in batch experiments and a plausible mechanism was proposed. The results showed that LA decarboxylation over cupric oxides at around 300 °C under acidic conditio...
Ungiminorine N-oxide was isolated from Puncrutium maritimum, and homolycorine N-oxide and O-methyl lycorenine N-oxide from Lapiedra martinezii. These compounds represent the first examples of naturally occurring Noxides from the Amaryllidaceae.
We demonstrate that configurational electronic entropy, previously neglected, in ab initio thermodynamics of materials can qualitatively modify the finite-temperature phase stability of mixed-valence oxides. While transformations from low-T ordered or immiscible states are almost always driven by configurational disorder (i.e., random occupation of lattice sites by multiple species), in FePO4-L...
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