Monoxide

About: Monoxide is a research topic. Over the lifetime, 2152 publications have been published within this topic receiving 36101 citations.

p-channel thin-film transistor using p-type oxide semiconductor, SnO

Abstract: This paper reports that among known p-type oxide semiconductors, tin monoxide (SnO) has a high hole mobility and produces good p-type oxide thin-film transistors (TFTs) Device-quality SnO films were grown epitaxially on (001) yttria-stabilized zirconia substrates at 575°C by pulsed laser deposition These exhibited a Hall mobility of 24cm2V−1s−1 at room temperature Top-gated TFTs, using epitaxial SnO channels, exhibited field-effect mobilities of 13cm2V−1s−1, on/off current ratios of ∼102, and threshold voltages of 48V

Cobalt oxide surface chemistry: The interaction of CoO(1 0 0), Co3O4(1 1 0) and Co3O4(1 1 1) with oxygen and water

Abstract: Cobalt oxides comprise two readily accessible cation oxidation states: Co 2+ and Co 3+ , which are thermodynamically competitive under common ambient conditions, and redox mechanisms connecting the two states are largely responsible for their success in partial oxidation catalysis. In our studies, CoO(1 0 0), Co 3 O 4 (1 1 0), and Co 3 O 4 (1 1 1) single crystal substrates have been investigated with X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), and low energy electron diffraction (LEED) for their surface reactivity toward O 2 and H 2 O and for their stability under reducing UHV conditions. There is facile inter-conversion between CoO and Co 3 O 4 stoichiometry at the oxide surface which, despite the compositional variability, remains well ordered in long-range structure. Surface impurities, however, can pin the surface at either CoO or Co 3 O 4 compositional extremes. Contrary to reports of a pressure gap that creates difficulty in oxide hydroxylation under UHV, it is pos sible to hydroxylate both cobalt monoxide and spinel oxide substrates with H 2 O, provided sufficient activation is available to dis sociate the water molecule.

CH and CC Bond Activation by Bare Transition‐Metal Oxide Cations in the Gas Phase

Abstract: Over the last decade the gas-phase chemistry of bare transition-metal oxide cations MO+ has received considerable attention. This interest is primarily due to the particular role of metal oxides in the oxidation of organic compounds in a variety of chemical and biochemical transformations. At a molecular level the simplest model system for these processes deals with reactions of bare metal-oxide ions in the gas phase. Due to the high oxophilicities of the early transition metals, their monoxide cations MO+ do not mediate O-atom transfer to any organic compounds at all. In contrast, monoxide cations of late transition metal can oxygenate a variety of hydro-carbons, and the most reactive ions, MnO+, FeO+, NiO+, OsO+, and PtO+, even activate methane. Insight into the reaction mechanisms of these oxidation processes can be obtained by analysis of reaction kinetics, isotope effects, product distributions etc., and for the reactions of MO+ with alkanes the initial CH bond activation by MO+ is often rate-determining. Interestingly, the high reactivity of some MO+ ions is not always associated with a decrease in regioselectivity; for example, FeO+ ions induce regiospecific γ-CH bond activation of dialkylketones in the gas phase. The situation for the epoxidation of olefins in the gas phase turns out to be even more complex than for condensedphase analogues. This is primarily because the metal ion that mediates O-atom transfer to the olefin also catalyzes the isomerization of the epoxides formed, to afford the energetically more stable aldehydes or ketones. Aromatic compounds can also be hydroxylated by MO+ ions, and particularly the oxidation of benzene by bare FeO+ ions in the gas phase reveals striking parallels to the metabolism of arenes. Furthermore, the storing capabilities of ion cyclotron resonance mass spectrometers even permit the design of catalytic processes in which a single metal ion converts more than one substrate molecule into an oxygenated product in a sequence of strictly bimolecular reactions. The most outstanding examples are the Pt+-mediated oxidation of methane by molecular oxygen and the Co+-mediated hydroxylation of benzene by N2O as oxidant. Finally, the key features of the gas-phase reactions are compared with observations in condensed-phase systems in which metal oxides are anticipated as central intermediates. The result of this comparison is promising in the sense that, in general, the understanding of transition-metal-mediated oxidations in the gas phase may lead to a more uniform description of these processes at a molecular level. Ultimately, it is hoped that gas-phase studies will serve as one of the building blocks in the evolution of tailor-made catalysts.