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Jonah Erlebacher - One of the best experts on this subject based on the ideXlab platform.
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dealloying silver gold alloys in neutral silver nitrate solution Porosity Evolution surface composition and surface oxides
Journal of The Electrochemical Society, 2008Co-Authors: Joshua Snyder, Kenneth J T Livi, Jonah ErlebacherAbstract:The electrochemistry of dealloying silver/gold alloys in neutral pH silver nitrate solution to form nanoporous gold (NPG) is discussed. At pH 7, Porosity Evolution was observed to occur at high potentials, above that required for oxygen Evolution, and within the nominal domain of the Pourbaix diagram where silver would be expected to form a passivating oxide. Electron microscopy shows that a small pore (∼5 nm) NPG is formed over a potential regime of 1.3-2.0 V vs normal hydrogen electrode, but electrochemical measurements show that the specific capacitance of samples over the same voltage range rises nearly threefold. The observations are explained in terms of residual surface oxides passivating the pores behind the dissolution front, which is itself acidified (and thus corrosive) due to an accumulation of protons associated with oxide formation and water dissociation. A model is proposed that is consistent with the electrochemical and microscopy results. This method of fabricating NPG has advantages of simplicity and safety, and the Porosity formation mechanism may be extended to other systems.
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Dealloying Silver/Gold Alloys in Neutral Silver Nitrate Solution: Porosity Evolution, Surface Composition, and Surface Oxides
Journal of The Electrochemical Society, 2008Co-Authors: Joshua Snyder, Kenneth J T Livi, Jonah ErlebacherAbstract:The electrochemistry of dealloying silver/gold alloys in neutral pH silver nitrate solution to form nanoporous gold (NPG) is discussed. At pH 7, Porosity Evolution was observed to occur at high potentials, above that required for oxygen Evolution, and within the nominal domain of the Pourbaix diagram where silver would be expected to form a passivating oxide. Electron microscopy shows that a small pore (∼5 nm) NPG is formed over a potential regime of 1.3-2.0 V vs normal hydrogen electrode, but electrochemical measurements show that the specific capacitance of samples over the same voltage range rises nearly threefold. The observations are explained in terms of residual surface oxides passivating the pores behind the dissolution front, which is itself acidified (and thus corrosive) due to an accumulation of protons associated with oxide formation and water dissociation. A model is proposed that is consistent with the electrochemical and microscopy results. This method of fabricating NPG has advantages of simplicity and safety, and the Porosity formation mechanism may be extended to other systems.
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Kinetic Monte Carlo Simulations of Porosity Evolution During Selective Dissolution From Ternary Alloys
2007Co-Authors: Jonah ErlebacherAbstract:Dealloying of uniform single phase alloys sometimes results in the formation of beautiful and functional nanoporous metals possessing mesoPorosity with ligaments and pore channels of order 10 nm. An example of such a material is nanoporous gold made by dealloying silver from silver/gold alloys. Kinetic Monte Carlo (KMC) methods have previously been used to elucidate the mechanisms of Porosity Evolution [1]. In these models, each atom of a system is tracked as they diffuse along the surface or as the less noble component dissolves into the electrolyte.
Joshua Snyder - One of the best experts on this subject based on the ideXlab platform.
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dealloying silver gold alloys in neutral silver nitrate solution Porosity Evolution surface composition and surface oxides
Journal of The Electrochemical Society, 2008Co-Authors: Joshua Snyder, Kenneth J T Livi, Jonah ErlebacherAbstract:The electrochemistry of dealloying silver/gold alloys in neutral pH silver nitrate solution to form nanoporous gold (NPG) is discussed. At pH 7, Porosity Evolution was observed to occur at high potentials, above that required for oxygen Evolution, and within the nominal domain of the Pourbaix diagram where silver would be expected to form a passivating oxide. Electron microscopy shows that a small pore (∼5 nm) NPG is formed over a potential regime of 1.3-2.0 V vs normal hydrogen electrode, but electrochemical measurements show that the specific capacitance of samples over the same voltage range rises nearly threefold. The observations are explained in terms of residual surface oxides passivating the pores behind the dissolution front, which is itself acidified (and thus corrosive) due to an accumulation of protons associated with oxide formation and water dissociation. A model is proposed that is consistent with the electrochemical and microscopy results. This method of fabricating NPG has advantages of simplicity and safety, and the Porosity formation mechanism may be extended to other systems.
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Dealloying Silver/Gold Alloys in Neutral Silver Nitrate Solution: Porosity Evolution, Surface Composition, and Surface Oxides
Journal of The Electrochemical Society, 2008Co-Authors: Joshua Snyder, Kenneth J T Livi, Jonah ErlebacherAbstract:The electrochemistry of dealloying silver/gold alloys in neutral pH silver nitrate solution to form nanoporous gold (NPG) is discussed. At pH 7, Porosity Evolution was observed to occur at high potentials, above that required for oxygen Evolution, and within the nominal domain of the Pourbaix diagram where silver would be expected to form a passivating oxide. Electron microscopy shows that a small pore (∼5 nm) NPG is formed over a potential regime of 1.3-2.0 V vs normal hydrogen electrode, but electrochemical measurements show that the specific capacitance of samples over the same voltage range rises nearly threefold. The observations are explained in terms of residual surface oxides passivating the pores behind the dissolution front, which is itself acidified (and thus corrosive) due to an accumulation of protons associated with oxide formation and water dissociation. A model is proposed that is consistent with the electrochemical and microscopy results. This method of fabricating NPG has advantages of simplicity and safety, and the Porosity formation mechanism may be extended to other systems.
Kenneth J T Livi - One of the best experts on this subject based on the ideXlab platform.
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dealloying silver gold alloys in neutral silver nitrate solution Porosity Evolution surface composition and surface oxides
Journal of The Electrochemical Society, 2008Co-Authors: Joshua Snyder, Kenneth J T Livi, Jonah ErlebacherAbstract:The electrochemistry of dealloying silver/gold alloys in neutral pH silver nitrate solution to form nanoporous gold (NPG) is discussed. At pH 7, Porosity Evolution was observed to occur at high potentials, above that required for oxygen Evolution, and within the nominal domain of the Pourbaix diagram where silver would be expected to form a passivating oxide. Electron microscopy shows that a small pore (∼5 nm) NPG is formed over a potential regime of 1.3-2.0 V vs normal hydrogen electrode, but electrochemical measurements show that the specific capacitance of samples over the same voltage range rises nearly threefold. The observations are explained in terms of residual surface oxides passivating the pores behind the dissolution front, which is itself acidified (and thus corrosive) due to an accumulation of protons associated with oxide formation and water dissociation. A model is proposed that is consistent with the electrochemical and microscopy results. This method of fabricating NPG has advantages of simplicity and safety, and the Porosity formation mechanism may be extended to other systems.
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Dealloying Silver/Gold Alloys in Neutral Silver Nitrate Solution: Porosity Evolution, Surface Composition, and Surface Oxides
Journal of The Electrochemical Society, 2008Co-Authors: Joshua Snyder, Kenneth J T Livi, Jonah ErlebacherAbstract:The electrochemistry of dealloying silver/gold alloys in neutral pH silver nitrate solution to form nanoporous gold (NPG) is discussed. At pH 7, Porosity Evolution was observed to occur at high potentials, above that required for oxygen Evolution, and within the nominal domain of the Pourbaix diagram where silver would be expected to form a passivating oxide. Electron microscopy shows that a small pore (∼5 nm) NPG is formed over a potential regime of 1.3-2.0 V vs normal hydrogen electrode, but electrochemical measurements show that the specific capacitance of samples over the same voltage range rises nearly threefold. The observations are explained in terms of residual surface oxides passivating the pores behind the dissolution front, which is itself acidified (and thus corrosive) due to an accumulation of protons associated with oxide formation and water dissociation. A model is proposed that is consistent with the electrochemical and microscopy results. This method of fabricating NPG has advantages of simplicity and safety, and the Porosity formation mechanism may be extended to other systems.
Huayao Zou - One of the best experts on this subject based on the ideXlab platform.
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Quantitative analyses of Porosity Evolution in tight grainstones: A case study of the Triassic Feixianguan formation in the Jiannan gas field, Sichuan Basin, China
Marine and Petroleum Geology, 2017Co-Authors: Guangwei Wang, Fang Hao, Xiangchun Chang, Caijun Lan, Huayao ZouAbstract:Abstract Tight grainstones, although widespread throughout the Lower Triassic Feixianguan Formation in the Sichuan Basin, have received little attention, in part, due to their lower Porosity and greater heterogeneity relative to their dolostone counterparts. Based on data from cores and thin sections, as well as petrophysical properties, the Feixianguan grainstones, representing a major gas reservoir in the Jiannan gas field were systemically analysed to better understand Porosity Evolution in tight carbonates that have experienced original oil accumulation and subsequent thermal cracking during progressive burial. The grainstones were divided into two types according to whether pyrobitumen was present, and their Porosity Evolutions were quantitatively reconstructed. Taking 40% as the original Porosity, the grainstones without pyrobitumen, which were ineffective palaeo-oil reservoirs, lost 21.94% and 3.13% of their porosities through marine and burial calcite cementation, respectively, and 13.34% by compaction, and have a current Porosity of 1.59%, thus allowing them to serve as major present-day gas reservoirs. Comparatively, pyrobitumen-bearing grainstones, which were once palaeo-oil reservoirs, lost 23.96% and 2.36% of their porosities through marine and burial calcite cementation, respectively; 11.4% by compaction, and 1.44% by pyrobitumen and have a current Porosity of 0.84%, thus making them ineffective gas reservoirs. This study provides a quantitative understanding of the close association between Porosity Evolution and reservoir effectiveness for the palaeo-oil charge and present-day gas accumulation with respect to diagenetic history, which is useful for the future exploration in tight gas limestone reservoirs.
M Cocco - One of the best experts on this subject based on the ideXlab platform.
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The Role of Porosity Evolution and fluid flow in frictional instabilities: A parametric study using a spring‐slider dynamic system
Geophysical Research Letters, 2010Co-Authors: Yuta Mitsui, M CoccoAbstract:[1] We have investigated the role of Porosity Evolution and fluid flow in frictional instabilities by analyzing the response of a single degree of freedom dynamic system. The spring slider is governed by rate- and state-dependent constitutive law. We also account for effective normal stress changes caused by thermal pressurization with constant or variable Porosity. Our simulations show that the stress drop during dynamic instabilities depends on constitutive parameters, Porosity Evolution, fluid flow as well as on the effective fault zone thickness, defined in this study as the ratio between the nominal thickness of the fault zone (w) and the hydraulically activated layer (why). Both Porosity Evolution and fluid flow can avoid the extremely large stress drop values inferred by thermal pressurization models and provide an attempt to reconcile them with seismological observations.
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the role of Porosity Evolution and fluid flow in frictional instabilities a parametric study using a spring slider dynamic system
Geophysical Research Letters, 2010Co-Authors: Yuta Mitsui, M CoccoAbstract:[1] We have investigated the role of Porosity Evolution and fluid flow in frictional instabilities by analyzing the response of a single degree of freedom dynamic system. The spring slider is governed by rate- and state-dependent constitutive law. We also account for effective normal stress changes caused by thermal pressurization with constant or variable Porosity. Our simulations show that the stress drop during dynamic instabilities depends on constitutive parameters, Porosity Evolution, fluid flow as well as on the effective fault zone thickness, defined in this study as the ratio between the nominal thickness of the fault zone (w) and the hydraulically activated layer (why). Both Porosity Evolution and fluid flow can avoid the extremely large stress drop values inferred by thermal pressurization models and provide an attempt to reconcile them with seismological observations.