| 1. |
- Csendes, Zita, et al.
(author)
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Superoxide dismutase inspired immobilised Ni(II)-protected amino acid catalysts Synthesis, characterisation, and catalytic activity
- 2014
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In: Journal of Molecular Catalysis A: Chemical. - : Elsevier BV. - 1381-1169. ; 395, s. 93-99
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Journal article (peer-reviewed)abstract
- Covalently anchored Ni(II)-C-protected amino acid (L-histidine, L-cysteine, and L-cystine) complexes inspired by the active site of the Ni-superoxide dismutase enzyme were synthesised using chloropropylated silica gel as support. The structural features of the surface complexes were studied by the Kjeldahl method and ICP-MS, mid/far IR, UV-vis diffuse reflectance, and X-ray absorption spectroscopies. The enzyme-like activities of the materials were determined in a biochemical test reaction. Covalent grafting and building the complex onto the surface of the support were successful in all cases. It was found that in many instances the structures obtained and the coordinating groups substantially varied upon changing the conditions of the syntheses. All the covalently immobilised Ni(II)-complexes displayed enzyme-like activity. They also were active in the liquid-phase oxidation of cyclohexene, providing the epoxide with high selectivity. (C) 2014 Elsevier B.V. All rights reserved.
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| 2. |
- Pedersen, Anders F., et al.
(author)
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Operando XAS Study of the Surface Oxidation State on a Monolayer IrOx, on RuOx and Ru Oxide Based Nanoparticles for Oxygen Evolution in Acidic Media
- 2018
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In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 122:2, s. 878-887
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Journal article (peer-reviewed)abstract
- Herein we present surface sensitive operando XAS L-edge measurements on IrOx/RuO2 thin films as well as mass-selected RuOx and Ru nanoparticles. We observed shifts of the white line XAS peak toward higher energies with applied electrochemical potential. Apart from the case of the metallic Ru nanoparticles, the observed potential dependencies were purely core-level shifts caused by a change in oxidation state, which indicates no structural changes. These findings can be explained by different binding energies of oxygenated species on the surface of IrOx and RuOx. Simulated XAS spectra show that the average Ir oxidation state change is strongly affected by the coverage of atomic O. The observed shifts in oxidation state suggest that the surface has a high coverage of O at potentials just below the potential where oxygen evolution is exergonic in free energy. This observation is consistent with the notion that the metal-oxygen bond is stronger than ideal.
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| 3. |
- Siddharth, Shukla, et al.
(author)
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Probing the three-dimensional porous and tortuous nature of absorptive glass mat (AGM) separators
- 2020
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In: Journal of Energy Storage. - : Elsevier BV. - 2352-152X .- 2352-1538. ; 2017:101003
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Journal article (peer-reviewed)abstract
- The valve regulated lead acid (VRLA) battery is a predominant electrochemical storage system that stores energy in a cheap, reliable and recyclable manner for innumerable applications. The absorptive glass mat (AGM) separator is a key component, which is pivotal for the successful functioning of the VRLA battery. Herein, the intricate three-dimensional (3D) porous structure of AGM separators has been unveiled using X-ray micro-computed tomography (microCT) analysis. X-ray microCT has quantified a variety of fiber and structural parameters including fiber orientation, porosity, tortuosity, pore size distribution, pore interconnectivity and pore volume distribution. A predictive model of hydraulic tortuosity has been developed based upon some of these fiber and structural parameters. Moreover, the pore size distribution extracted via X-ray microCT analysis has served as a benchmark for making a comparison with the existing analytical model of the pore size distribution of AGM separators. Pore size distributions obtained via the existing analytical model and through X-ray microCT analysis are in close agreement.
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