| 1. |
- Budnyak, Tetyana M., et al.
(författare)
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Bile acids adsorption by chitoan-fumed silica enterosorbent
- 2019
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Ingår i: Colloid and Interface Science Communications. - : Elsevier BV. - 2215-0382. ; 32
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid composites from chitosan and fumed silica were synthesized and applied for the adsorption of bile acids (BA), e.g. cholic (CA) and taurocholic (TCA) acids. The chitosan immobilization was confirmed by infrared spectroscopy and the corresponding stability of the composites was confirmed by tests with the analytical reagent ninhydrin. The effects of adsorption parameters such as initial concentration of BA and pH were evaluated. The synthesized composite shows higher affinity and adsorption capacity toward TCA in comparison to CA. The results of equilibrium study for BA adsorption by the synthesized composite were analyzed by application of Langmuir, Freundlich and Temkin isotherm models. Adsorption capacity of chitosan-fumed silica composite was 97 mu mol/g for TCA and 43 mu mol/g for CA based on the applied Freundlich isoterm model. Our results show the potential of biopolymeric-inorganic composites for application as efficient enterosorbent in medical practice.
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| 2. |
- Corkett, Alex J., et al.
(författare)
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Band Gap Tuning in Bismuth Oxide Carbodiimide Bi2O2NCN
- 2019
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 58:9, s. 6467-6473
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Tidskriftsartikel (refereegranskat)abstract
- Layered bismuth oxides exhibit a broad range of tunable physical properties as a result of their excellent structural versatility which facilitates compositional substitutions at both cationic and anionic positions. Here we expand this family in a new direction through the preparation of the first example of a bismuth-containing oxide carbodiimide, Bi2O2NCN, which assumes an extended variant of the anti-ThCr2Si2 structure-type adopted by Bi(2)O(2)Ch (Ch = Se or Te) oxide chalcogenides. Electronic structure calculations reveal the title compound to be an indirect band gap semiconductor with a band gap of approximately 1.4 eV, in good agreement with the measured value of 1.8 eV, and intermediate between that of structurally related Bi2O2S (1.12 eV) and beta-Bi2O3 (2.48 eV). Mott-Schottky experiments demonstrate Bi2O2NCN to be an n-type semiconductor with a conduction band edge position of -0.37 V vs reversible hydrogen electrode. This study highlights the pseudochalcogenide nature of the N-=C=N- carbodiimide anion, which may be substituted in place of oxide or chalcogenide anions in this and potentially other structural classes as an effective means of electronic tuning.
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| 3. |
- Ertl, Michael, et al.
(författare)
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Mössbauerite as Iron-Only Layered Oxyhydroxide Catalyst for WO3 Photoanodes
- 2019
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 58:15, s. 9655-9662
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Tidskriftsartikel (refereegranskat)abstract
- Mössbauerite, a trivalent iron-only layered oxyhydroxide, has been recently identified as an electrocatalyst for water oxidation. We investigated the material as potential cocatalyst for photoelectrochemical water oxidation on semiconductor photoanodes. The band edge positions of mössbauerite were determined for the first time with a combination of Mott-Schottky analysis and UV-vis diffuse reflectance spectroscopy. The positive value of the Mott-Schottky slope and the flatband potential of 0.34 V vs reversible hydrogen electrode (RHE) identifies the material as an n-type semiconductor, but bare mössbauerite does not produce noticeable photocurrent during water oxidation. Type-II heterojunction formation by facile drop-casting with WO3 thin films yielded photoanodes with amended charge carrier separation and photocurrents up to 1.22 mA cm(-2) at 1.23 V vs RHE. Mössbauerite is capable of increasing the charge carrier separation at lower potential and improving the photocurrent during photoelectrochemical water oxidation. The rise in photocurrent of the mössbauerite-functionalized WO3 photoanode thus originates from improved charge carrier separation and augmented hole collection efficiency. Our results highlight the potential of mössbauerite as a second-phase catalyst for semiconductor electrodes.
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| 4. |
- Ma, Zili, et al.
(författare)
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Quaternary Core-Shell Oxynitride Nanowire Photoanode Containing a Hole-Extraction Gradient for Photoelectrochemical Water Oxidation
- 2019
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 11:21, s. 19077-19086
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Tidskriftsartikel (refereegranskat)abstract
- A nanowire photoanode SrTaO2N, a semiconductor suitable for overall water-splitting with a band gap of 2.3 eV, was coated with functional overlayers to yield a core-shell structure while maintaining its one-dimensional morphology. The nanowires were grown hydrothermally on tantalum, and the perovskite-related oxynitride structure was obtained by nitridation. Three functional overlayers have been deposited on the nanowires to enhance the efficiency of photoelectrochemical (PEC) water oxidation. The deposition of TiOx protects the oxynitride from photocorrosion and suppresses charge-carrier recombination at the surface. Ni(OH)(x) acts a hole-storage layer and decreases the dark-current contribution. This leads to a significantly improved extraction of photogenerated holes to the electrode-electrolyte surface. The photocurrents can be increased by the deposition of a cobalt phosphate (CoPi) layer as a cocatalyst. The heterojunction nanowire photoanode generates a current density of 0.27 mA cm(-2) at 1.23 V vs the reversible hydrogen electrode (RHE) under simulated sunlight (AM 1.5G). Simultaneously, the dark-current contribution, a common problem for oxynitride photoanodes grown on metallic substrates, is almost completely minimized. This is the first report of a quaternary oxynitride nanowire photoanode in core-shell geometry containing functional overlayers for synergetic hole extraction and an electrocatalyst.
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