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Showing 1 to 20 of 23 for “"Birnessite"”.
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Superoxide-assisted solid-state synthesis of birnessite type MnO2 materials: physiochemical properties and electrochemical viability
… solid-state synthesis of layered birnessite manganese dioxide. This synthetic method produces materials with variable physiochemical properties that can be tuned depending on the oxidant amount used in the synthesis. To further understand the physiochemical tunability of this …
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The catalytic role of birnessite in the Maillard reaction and the abiotic formation of humic substances
… effect on browning in the glucose-glycine-birnessite system. The catalytic effect of birnessite on the Maillard reaction was still evident even under conditions of complete darkness and therefore may occur at any depth in soil and related environments. Molecular topological analysis was …
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STUDIES OF 2D LAYERED MnO2 AND MoS2 FOR ANTIBACTERIAL AND ELECTROCHEMICAL APPLICATIONS
… applications. A further research effort studied birnessite, focusing on the activity of exfoliated birnessite and the role of birnessite defects for water oxidation. The catalytic activity of layered MnO2 has been studied widely. Birnessite has the lowest oxygen evolution reaction (OER) activity …
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Long-range extracellular electron transport by dissimilatory metal-reducing bacteria across a physical separation
… separate DMRB from the insoluble Mn(IV) mineral birnessite were etched into silicon using photolithography or electron beam lithography. The central feature of the microfluidic reactors was a 1.5 μm thick wall containing an array of <200 nm deep pores that allowed the diffusion of solutes but not …
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Lead Sorption Efficiencies of Natural and Sunthetic Mn and Fe-oxides
… The Mn-oxide phases examined included synthetic birnessite, natural and synthetic cryptomelane, and natural and synthetic pyrolusite; the Fe-oxides studied were synthetic akaganeite, synthetic ferrihydrite, natural and synthetic goethite, and natural and synthetic hematite. The sorption flow …
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The interaction of cobalt, amino acids, and cobalt amino acid complexes with sediment surfaces
… complexes on both Na⁺-montmorillonite and Na⁺-birnessite (MnO₂). Amino acids were also adsorbed on Co²⁺-saturated montmorillonite and birnessite. The oxidation state and chemical nature of sorbed cobalt and the chemical nature of the amino acid amine groups were investigated using x-ray …
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THE EFFECT OF ALTERNATING DISTRIBUTION OF TRANSITION METALS IN LAYERED MATERIALS ON OXYGEN EVOLUTION CATALYSIS
… a study of the effect of surface reduction of birnessite on catalytic activity. A sample of birnessite was reduced by stirring with sodium dithionite, in which case the oxidation states of surface Mn decreased faster than those of inside Mn. We characterized the difference between the oxidation …
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Transition metal oxide layered materials as catalyst and precatalyst for green energy applications: Oxygen evolution reaction and Fischer-Tropsch synthesis
… materials, particularly transition metal oxides, birnessite and lithium cobalt oxide as catalytic materials for the conversion of renewable energy into fuels and. In order to accomplish this, we principally studied the energy intensive oxygen evolution reaction (OER) in water splitting, and …
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Mechanistic understanding of biogenic Mn-oxide mediated bisphenol A degradation
… 2-bio] produced by R. AzwK-3b is a hexagonal-birnessite-like colloidal phase. This initial phase is known to undergo “aging” process and transforms into triclinic-birnessite-like particulate phase. We prepared two phases of MnO2-bio (colloidal and particulate) and their synthetic counterparts …
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Understanding Heterogenous Catalysis on Zeolites and Manganese Oxides
… of the possible mechanisms was conducted on birnessite (OL) and cryptomelane (OMS-2). Using acetaldehyde as the substrate molecule, the mechanism on Birnessite, is proposed to proceed via a solvent assisted Eley-Rideal mechanism with molecular hydrogen in the liquid phase. Birnessite has no …
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Synthesis and characterization of high-performance supercapacitor devices based on carbon/MnO2 composite and carbonized iron cations adsorbed onto polyaniline/nickel graphene foam
… graphene foam (C-Fe/PANI/Ni-GF) and birnessite-type MnO2/carbon composite electrode materials were investigated for supercapacitor applications. The C-Fe/PANI/Ni-GF electrode material was directly synthesized on a current collector by pyrolysis of the iron-PANI mixture coated on …
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Investigating the Effect of Electrolyte Concentration and Charging Protocol on Materials Utilization in Rechargeable Zinc Manganese Dioxide Batteries
… link between capacity fade and the amount of birnessite (another polymorph of MnO<sub>2</sub>) that appears to be formed. We uncover the underlying cause of cathode capacity fade by cycling industrially produced EMD cathodes at various levels of theoretical one-electron capacity, termed depth …
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The impact of abiotic and biogenic mn oxide coatings on contaminant mobility, bioavailability, and attenuation
… potentially forms a polymer-like precursor to birnessite consistent with the phyllomanganate family. Surface properties of the coated bacteria are dominated by the oxide as Zn formed inner-sphere complexes resulting in octahedral structures. On the other hand, sorption to the sheathed L. …
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The characterisation of Manganese (IV) compounds and the study of the thermal decomposition of Potassium Chlorate alone and with Mn(IV) and other oxides and salts
… parameters were established. A compound - sodium birnessite- was identified as a significant agent in the determination of curing properties. It was synthesised and its curing properties alone and in combination with other manganese dioxide compounds was evaluated. In an effort to find a specific …
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Uranium isotopic fractionation induced by U(VI) adsorption onto common aquifer minerals
… induced by U(VI) adsorption onto goethite, birnessite, illite, quartz, and complex aquifer materials. The influence of U(VI) speciation on fractionation was also examined by measuring differences between fractionation factors accompanying the adsorption of uranyl, uranyl hydroxyl, uranyl …
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Composites of Spherical Polyelectrolyte Brushes and Nanoparticles – Synthesis, Characterization and Their Use in Catalysis
… topology built up from MnO6 octahedra denoted as birnessite. The PXRD patterns revealed a disorder along the stacking direction of the single layers of hexagonal sheets. Furthermore, the structure of the composite material observed by TEM strongly differs compared to that in cryoTEM micrographs. …
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DESCRIPTION OF POLARONS IN LAYERED TRANSITION METAL OXIDES USING THE r2SCAN DENSITY FUNCTIONAL WITH FULLY NONLOCAL CORRECTIONS AND EFFECT OF STRAIN ON THE BAND GAP OF MONOLAYER MOLYBDENUM DISULFIDE
… literature values for U and Ud, we investigated birnessite (KnMnO2, n = 0.03) and KnNiO2, n = 0.03. With one K atom intercalated in a supercell, both materials show a localized eg polaronic state on the transition metal ion reduced by the K atom, when the geometry is calculated using published U …
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Characterization of Uranium and Rare Earth Element Mobility and Attenuation Downstream of Decommissioned Tailings Impoundments at the Bicroft Mine near Bancroft, Ontario
… that Fe- and Mn-oxyhydroxides, goethite, and birnessite are the main mineral hosts for U and REEs in both the colloids and sediments. In addition, detrital grains of U- and REE-bearing minerals were found >200 m downstream in colloids and wetland sediments, showing the potential for long range …
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Cycling of Iron and Manganese (Oxyhydr)oxides in the Presence of Organic Matter
… we see no measurable photoreduction of triclinic birnessite in similar experiments. We also show that AQYs of 𝛿-MnO₂ photoreduction in natural filtered waters from three water bodies in Cape Cod, MA (Siders Pond, Oyster Pond, and seawater) are similar. We use this AQY response with wavelength to …
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Electrochemical properties of crystalline polymorphs of MnO2 in aluminum and zinc metal batteries
… polymorphs of MnO<sub>2</sub> are used: birnessite (δ-MnO<sub>2</sub>), a layered structure, and todorokite, a seldomly studied structure composed of large tunnels. For the Al batteries, two electrolyte were used: an ionic liquid containing aluminium chloride and …
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