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Patent

Defect engineering in metal oxides via surfaces

TL;DR: In this article, the authors present methods for controlling defects in materials, including point defects, such as interstitials and vacancies, and extended defects, including dislocations and clusters, which are useful for processing materials by controlling defects to access beneficial physical, optical, chemical and/or electronic properties.
Abstract: The present invention provides methods for controlling defects in materials, including point defects, such as interstitials and vacancies, and extended defects, including dislocations and clusters. Defect control provided by the present invention allows for fabrication and processing of materials and/or structures having a selected abundance, spatial distribution and/or concentration depth profile of one or more types of defects in a material, such as vacancies and/or interstitials in a crystalline material. Methods of the invention are useful for processing materials by controlling defects to access beneficial physical, optical, chemical and/or electronic properties.
Citations
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Patent
24 May 2012
TL;DR: In this paper, metal oxide catalysts comprising various dopants are provided, which are useful as heterogenous catalysts in a variety of catalytic reactions, for example, the oxidative coupling of methane to C2 hydrocarbons such as ethane and ethylene.
Abstract: Metal oxide catalysts comprising various dopants are provided. The catalysts are useful as heterogenous catalysts in a variety of catalytic reactions, for example, the oxidative coupling of methane to C2 hydrocarbons such as ethane and ethylene. Related methods for use and manufacture of the same are also disclosed.

73 citations

Patent
23 May 2013
TL;DR: In this paper, a system and methods conducive to the formation of one or more alkene hydrocarbons using a methane source and an oxidant in an OCM reaction are provided.
Abstract: Systems and methods conducive to the formation of one or more alkene hydrocarbons using a methane source and an oxidant in an oxidative coupling of methane (OCM) reaction are provided. One or more vessels each containing one or more catalyst beds containing one or more catalysts each having similar or differing chemical composition or physical form may be used. The one or more catalyst beds may be operated under a variety of conditions. At least a portion of the catalyst beds may be operated under substantially adiabatic conditions. At least a portion of the catalyst beds may be operated under substantially isothermal conditions.

49 citations

Patent
07 Jan 2015
TL;DR: In this article, an integrated system for the production of higher hydrocarbon compositions from methane using an oxidative coupling of methane system to convert methane to ethylene, followed by conversion of ethylene to selectable higher hydrocarbons.
Abstract: Integrated systems are provided for the production of higher hydrocarbon compositions, for example liquid hydrocarbon compositions, from methane using an oxidative coupling of methane system to convert methane to ethylene, followed by conversion of ethylene to selectable higher hydrocarbon products Integrated systems and processes are provided that process methane through to these higher hydrocarbon products

46 citations

Patent
11 Jan 2013
TL;DR: In this article, an oxidative coupling of methane (OCM) product gas comprising ethane and ethylene is introduced to a separation unit comprising two separators, and the OCM product gas is separated to provide a C2-rich effluent, a methane rich effluent and a nitrogen-rich discharge.
Abstract: Disclosed herein are processes for producing and separating ethane and ethylene. In some embodiments, an oxidative coupling of methane (OCM) product gas comprising ethane and ethylene is introduced to a separation unit comprising two separators. Within the separation unit, the OCM product gas is separated to provide a C2-rich effluent, a methane-rich effluent, and a nitrogen-rich effluent. Advantageously, in some embodiments the separation is achieved with little or no external refrigeration requirement.

43 citations

Patent
29 Nov 2012
TL;DR: Nanowires useful as heterogeneous catalysts are provided in this article, which is useful in a variety of catalytic reactions, for example, the oxidative coupling of methane to C2 hydrocarbons.
Abstract: Nanowires useful as heterogeneous catalysts are provided. The nanowire catalysts are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane to C2 hydrocarbons. Related methods for use and manufacture of the nanowires are also disclosed.

41 citations

References
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Journal ArticleDOI
07 Jul 1972-Nature
TL;DR: Water photolysis is investigated by exploiting the fact that water is transparent to visible light and cannot be decomposed directly, but only by radiation with wavelengths shorter than 190 nm.
Abstract: ALTHOUGH the possibility of water photolysis has been investigated by many workers, a useful method has only now been developed. Because water is transparent to visible light it cannot be decomposed directly, but only by radiation with wavelengths shorter than 190 nm (ref. 1).

27,819 citations

Journal ArticleDOI
TL;DR: The slow pace of hazardous waste remediation at military installations around the world is causing a serious delay in conversion of many of these facilities to civilian uses as discussed by the authors, which is a serious problem.
Abstract: The civilian, commercial, and defense sectors of most advanced industrialized nations are faced with a tremendous set of environmental problems related to the remediation of hazardous wastes, contaminated groundwaters, and the control of toxic air contaminants. For example, the slow pace of hazardous waste remediation at military installations around the world is causing a serious delay in conversion of many of these facilities to civilian uses. Over the last 10 years problems related to hazardous waste remediation have emerged as a high national and international priority.

17,188 citations

Journal ArticleDOI
Ryoji Asahi1, Takeshi Morikawa1, T. Ohwaki1, Koyu Aoki1, Y. Taga1 
13 Jul 2001-Science
TL;DR: Film and powders of TiO2-x Nx have revealed an improvement over titanium dioxide (TiO2) under visible light in optical absorption and photocatalytic activity such as photodegradations of methylene blue and gaseous acetaldehyde and hydrophilicity of the film surface.
Abstract: To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.

11,402 citations

Journal ArticleDOI
TL;DR: In this article, the authors focus on interfacial processes and summarize some of the operating principles of heterogeneous photocatalysis systems, including the electron transfer and energy transfer processes in photocatalytic reactions.
Abstract: In 1972, Fujishima and Honda discovered the photocatalytic splitting of water on TiO{sub 2} electrodes. This event marked the beginning of a new era in heterogeneous photocatalysis. Since then, research efforts in understanding the fundamental processes and in enhancing the photocatalytic efficiency of TiO{sub 2} have come from extensive research performed by chemists, physicists, and chemical engineers. Such studies are often related to energy renewal and energy storage. In recent years, applications to environmental cleanup have been one of the most active areas in heterogeneous photocatalysis. This is inspired by the potential application of TiO{sub 2}-based photocatalysts for the total destruction of organic compounds in polluted air and wastewaters. There exists a vast body of literature dealing with the electron transfer and energy transfer processes in photocatalytic reactions. A detailed description of these processes is beyond the scope of this review. Here, the authors tend to focus on interfacial processes and to summarize some of the operating principles of heterogeneous photocatalysis. In section 2, the authors first look at the electronic excitation processes in a molecule and in a semiconductor substrate. The electronic interaction between the adsorbate molecule and the catalyst substrate is discussed in terms of the catalyzed ormore » sensitized photoreactions. In section 3, thermal and photocatalytic studies on TiO{sub 2} are summarized with emphasis on the common characteristics and fundamental principles of the TiO{sub 2}-based photocatalysis systems. In section 4, they address the research effort in the electronic modification of the semiconductor catalysts and its effect on the photocatalytic efficiency. Several representative examples will be presented including the Schottky barrier formation and modification at metal-semiconductor interfaces. Some concluding remarks and future research directions will be given in the final section. 160 refs.« less

10,719 citations

Journal ArticleDOI
01 May 2008-Nature
TL;DR: It is shown, using a simple analytical example, that memristance arises naturally in nanoscale systems in which solid-state electronic and ionic transport are coupled under an external bias voltage.
Abstract: Anyone who ever took an electronics laboratory class will be familiar with the fundamental passive circuit elements: the resistor, the capacitor and the inductor. However, in 1971 Leon Chua reasoned from symmetry arguments that there should be a fourth fundamental element, which he called a memristor (short for memory resistor). Although he showed that such an element has many interesting and valuable circuit properties, until now no one has presented either a useful physical model or an example of a memristor. Here we show, using a simple analytical example, that memristance arises naturally in nanoscale systems in which solid-state electronic and ionic transport are coupled under an external bias voltage. These results serve as the foundation for understanding a wide range of hysteretic current-voltage behaviour observed in many nanoscale electronic devices that involve the motion of charged atomic or molecular species, in particular certain titanium dioxide cross-point switches.

8,971 citations