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828 results on '"Kulesza, Pawel J."'

207. FeIII48‐Containing 96‐Tungsto‐16‐Phosphate: Synthesis, Structure, Magnetism and Electrochemistry.

Author

Goura, Joydeb, Bassil, Bassem S., Bindra, Jasleen K., Rutkowska, Iwona A., Kulesza, Pawel J., Dalal, Naresh S., and Kortz, Ulrich

Subjects
ELECTROCHEMISTRY, MAGNETISM, PHOSPHATES, SINGLE crystals, POLYANIONS
Abstract

The 48‐FeIII‐containing 96‐tungsto‐16‐phosphate, [FeIII48(OH)76(H2O)16(HP2W12O48)8]36− (Fe48), has been synthesized and structurally characterized. This polyanion comprises eight equivalent {FeIII6P2W12} units that are linked in an end‐on fashion forming a macrocyclic assembly that contains more iron centers than any other polyoxometalate (POM) known to date. The novel Fe48 was synthesized by a simple one‐pot reaction of an {Fe22} coordination complex with the hexalacunary {P2W12} POM precursor in water. The title polyanion was characterized by single‐crystal XRD, FTIR, TGA, magnetic and electrochemical studies. [ABSTRACT FROM AUTHOR]

Published
2020
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220. Toward Pt-Free Anion-Exchange Membrane Fuel Cells: Fe–Sn Carbon Nitride–Graphene Core–Shell Electrocatalysts for the Oxygen Reduction Reaction

Author

Negro, Enrico, primary, Bach Delpeuch, Antoine, additional, Vezzù, Keti, additional, Nawn, Graeme, additional, Bertasi, Federico, additional, Ansaldo, Alberto, additional, Pellegrini, Vittorio, additional, Dembinska, Beata, additional, Zoladek, Sylwia, additional, Miecznikowski, Krzysztof, additional, Rutkowska, Iwona A., additional, Skunik-Nuckowska, Magdalena, additional, Kulesza, Pawel J., additional, Bonaccorso, Francesco, additional, and Di Noto, Vito, additional

Published
2018
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221. 15-Copper(ii)-containing 36-tungsto-4-silicates(iv) [Cu15O2(OH)10X(A-α-SiW9O34)4]25−(X = Cl, Br): synthesis, structure, magnetic properties, and electrocatalytic CO2reduction

Author

Bassil, Bassem S., primary, Haider, Ali, additional, Ibrahim, Masooma, additional, Mougharbel, Ali S., additional, Bhattacharya, Saurav, additional, Christian, Jonathan H., additional, Bindra, Jasleen K., additional, Dalal, Naresh S., additional, Wang, Meng, additional, Zhang, Guangjin, additional, Keita, Bineta, additional, Rutkowska, Iwona A., additional, Kulesza, Pawel J., additional, and Kortz, Ulrich, additional

Published
2018
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223. Activation of Reduced-Graphene-Oxide Supported Pt Nanoparticles by Aligning with WO3-Nanowires toward Oxygen Reduction in Acid Medium: Diagnosis with Rotating-Ring-Disk Voltammetry and Double-Potential-Step Chronocoulometry

Author

Rutkowska, Iwona A., primary, Wadas, Anna, additional, Zoladek, Sylwia, additional, Skunik-Nuckowska, Magdalena, additional, Miecznikowski, Krzysztof, additional, Negro, Enrico, additional, Noto, Vito Di, additional, Zlotorowicz, Agnieszka, additional, Zelenay, Piotr, additional, and Kulesza, Pawel J., additional

Published
2018
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225. Solar-driven water oxidation and decoupled hydrogen production mediated by an electron-coupled-proton buffer

Author

Bloor, Leanne G., Solarska, Renata, Bienkowski, Krzysztof, Kulesza, Pawel J., Augustynski, Jan, Symes, Mark D., and Cronin, Leroy

Abstract

Solar-to-hydrogen photoelectrochemical cells (PECs) have been proposed as a means of converting sunlight into H2 fuel. However, in traditional PECs, the oxygen evolution reaction and the hydrogen evolution reaction are coupled, and so the rate of both of these is limited by the photocurrents that can be generated from the solar flux. This in turn leads to slow rates of gas evolution that favor crossover of H2 into the O2 stream and vice versa, even through ostensibly impermeable membranes such as Nafion. Herein, we show that the use of the electron-coupled-proton buffer (ECPB) H3PMo12O40 allows solar-driven O2 evolution from water to proceed at rates of over 1 mA cm–2 on WO3 photoanodes without the need for any additional electrochemical bias. No H2 is produced in the PEC, and instead H3PMo12O40 is reduced to H5PMo12O40. If the reduced ECPB is subjected to a separate electrochemical reoxidation, then H2 is produced with full overall Faradaic efficiency.

Published
2016

235. Activation of Reduced-Graphene-Oxide Supported Pt Nanoparticles by Aligning with WO3-Nanowires toward Oxygen Reduction in Acid Medium: Diagnosis with Rotating-Ring-Disk Voltammetry and Double-Potential-Step Chronocoulometry.

Author

Rutkowska, Iwona A., Wadas, Anna, Zoladek, Sylwia, Skunik-Nuckowska, Magdalena, Miecznikowski, Krzysztof, Kulesza, Pawel J., Zlotorowicz, Agnieszka, Zelenay, Piotr, Negro, Enrico, and Di Noto, Vito

Subjects
GRAPHENE oxide, NANOPARTICLES, TUNGSTEN, OXYGEN, POROSITY
Abstract

The chemically-reduced graphene-oxide has been used as support to anchor catalytic Pt nanoparticles and, while subsequently modified with tungsten oxide nanowires, has produced a hybrid electrocatalytic system for electroreduction of oxygen in acid medium. Such characteristics of reduced graphene oxide as defective surface and low degree of organization of graphitic structures facilitate dispersion of platinum nanocenters. Further combination with WO3 nanonowires is expected to increase the system's interfacial hydrophilicity and porosity. Most likely WO3 nanostructures are attached mainly to the edges of graphene thus preventing its stacking and creating space for the flux of oxygen and the reaction products. The results of electrochemical diagnostic experiments are consistent with the view that the electrocatalytic activity of the system utilizing tungsten oxide nanowires toward the reduction of oxygen in acid medium has been enhanced even at the Pt loading as low as 30 μg cm-2. Furthermore, the rotating ring-disk electrode voltammetry data is consistent with decreased formation of the undesirable hydrogen peroxide intermediate in the presence of WO3. The conclusions are supported with mechanistic and kinetic studies performed with use of double-potential-step chronocoulometry as an alternative diagnostic tool to rotating ring-disk voltammetry. [ABSTRACT FROM AUTHOR]

Published
2018
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239. Electron self-exchange dynamics of hexacyanoferrate in redox polyether hybrid molten salts containing polyether-tailed counterions

Author

Kulesza, Pawel J., Dickinson, Enders, Williams, Mary Elizabeth, Hendrickson, Susan M., Malik, Marcin A., Miecznikowski, Krzysztof, and Murray, Royce W.

Subjects
Ammonium chloride -- Research, Ammonium chloride -- Electric properties, Ammonium paratungstate -- Research, Ammonium paratungstate -- Electric properties, Ammonium compounds -- Research, Ammonium compounds -- Electric properties, Ferrites (Magnetic materials) -- Research, Glycol ethers -- Research, Glycol ethers -- Electric properties, Chemistry, Physical and theoretical -- Research, Chemicals, plastics and rubber industries
Abstract

A highly viscous room-temperature redox polyether hybrid melt was prepared by combining the hexacyanoferrate(III) with a quaternary ammonium countercation consisting of triethylammonium connected to a poly(ethylene glycol) methyl ether. The microelectrode voltammetry and potential step chronoamperometry in the undiluted melt give an apparent diffusion coefficient of D(sub APP) = 2.5 x 10(super -10) cm(super 2)/s at 20 degree Centigrade.

Published
2001

249. 15-Copper(ii)-containing 36-tungsto-4-silicates(iv) [Cu15O2(OH)10X(A-α-SiW9O34)4]25− (X = Cl, Br): synthesis, structure, magnetic properties, and electrocatalytic CO2 reduction

Author

Bassil, Bassem S., Haider, Ali, Ibrahim, Masooma, Mougharbel, Ali S., Bhattacharya, Saurav, Christian, Jonathan H., Bindra, Jasleen K., Dalal, Naresh S., Wang, Meng, Zhang, Guangjin, Keita, Bineta, Rutkowska, Iwona A., Kulesza, Pawel J., and Kortz, Ulrich

Subjects
COPPER, SILICATES, ELECTROCHEMICAL analysis
Abstract

The 15-copper(ii)-containing 36-tungsto-4-silicates [Cu15O2(OH)10X(A-α-SiW9O34)4]25− (X = Cl, 1; Br, 2) have been prepared in 70% yield by reaction of the trilacunary 9-tungstosilicate precursor [A-α-SiW9O34]10− with Cu2+ ions in aqueous pH 8 medium. Both polyanions 1 and 2 were isolated as hydrated mixed potassium/sodium salts and characterized in the solid state by FT-IR, TGA, single-crystal XRD, and elemental analysis. DC magnetic susceptibility measurements from 1.8–300 K established the ground state to be paramagnetic with a magnetic moment corresponding to 15 uncoupled Cu2+ (S = 1/2) ions. EPR measurements and simulations were consistent with this analysis. Electrochemical studies were performed for polyanions 1 and 2 dissolved in solution to elucidate the electroactivity of both copper and tungstate sites. Using 2 as a representative example, the electrocatalytic activity towards CO2 reduction upon deposition on a glassy carbon electrode surface, while retaining selectivity relative to hydrogen evolution, was demonstrated. [ABSTRACT FROM AUTHOR]

Published
2018
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