| 5111. |
- Li, F., et al.
(författare)
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Fabrication and assembly behavior of square microcapsules
- 2006
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 18:3, s. 270-
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Tidskriftsartikel (refereegranskat)abstract
- Square microcapsules have been fabricated within porous silicon membranes. The capsules float in water when released from the membrane (see Figure). Dry capsules float with one of their edges pointing down, but after uptake of water, they float face down; the edge-down capsules assemble end-to-end while the face-down capsules assemble face-to-face.
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| 5112. |
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| 5113. |
- Li, Feng, et al.
(författare)
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Formation of nanotapes by co-assembly of triblock peptide copolymers and polythiophenes in aqueous solution
- 2009
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Ingår i: SOFT MATTER. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 5:8, s. 1668-1673
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Tidskriftsartikel (refereegranskat)abstract
- Nanotapes are formed by the co-assembly of triblock peptide copolymers with an amino acid-substituted polythiophene derivative (PTT). The driving force for the assembly is ionic interaction (complex coacervation). These nanotapes were visualized by atomic force microscopy and confocal laser scanning microscopy. The interactions between the triblock peptide copolymers and the PTT are also expressed in the steady state and time resolved fluorescence spectra. The steady-state spectra indicate that upon interaction with the peptide copolymer, the backbone of the PTT adopts a rather twisted, and definitely less, aggregated conformation. The time-resolved fluorescence decay studies further confirm this interpretation. The structure of these nanotapes at the mesoscopic scale depends, among other physical chemical parameters, on the concentrations of its constituents.
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| 5114. |
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| 5115. |
- Li, Fenghong, et al.
(författare)
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Modified Surface Electronic and Magnetic Properties of La(0.6)Sr(0.4)MnO(3) Thin Films for Spintronics Applications
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:34, s. 16947-16953
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Tidskriftsartikel (refereegranskat)abstract
- We present the surface electronic and magnetic properties of half-metal La(0.6)Sr(0.4)MnO(3) (LSMO) thin film modified by a simple cleaning procedure, the so-called SC1 (5 H(2)O, 1 NH(4)OH, I H(2)O(2)), at 85 degrees C for 10-40 min in ambient atmosphere. In this study, photoemission spectroscopy (XPS/UPS), X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD) are used to characterize these properties of the manganites. Thanks to SC1 treatment, the work function of LSMO changes from 4.0-4.1 to 4.8-4.9 eV obtained from UPS measurements, while its surface roughness changes from 0.268 to 0.796 nm in AFM images. Combined 0 1s, Mn 2p, Sr 3d, La 4d, and Mn 3s core-level XPS spectroscopy investigations suggest that Mn and Sr contents decrease at the surface and the Mn value becomes 3.7 due to SC1 treament. Mn L-edge XAS spectra of LSMO thin film demonstrate that SC1 treatment results in a removal of Mn(2+) and an increase of the Mn(4+) concentration. OK-edge XAS spectra further prove an enhancement of hybridization between O 2p orbitals and e(g)down arrow, of Mn 3d induced by more Mn(4+). XMCD results show that SC1 treatment does not induce any drastic changes of magnetic properties of the LSMO thin film surface.
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| 5116. |
- Li, Feng, et al.
(författare)
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Nanowires Formed by the Co-Assembly of a Negatively Charged Low-Molecular Weight Gelator and a Zwitterionic Polythiophene
- 2010
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Ingår i: ChemPhysChem. - : John Wiley and Sons, Ltd. - 1439-4235 .- 1439-7641. ; 11:9, s. 1956-1960
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Tidskriftsartikel (refereegranskat)abstract
- Conjugated organic nanowires have been prepared by co-assembling a carboxylate containing low-molecular weight gelator (LMWG) and an amino acid substituted polythiophene derivative (PTT). Upon introducing the zwitterionic polyelectrolyte PTT to a basic molecular solution of the organogelator, the negative charges on the LMWG are compensated by the positive charges of the PTT. As a result, nanowires form through co-assembly. These nanowires are visualized by both transmission electron microscopy (TEM) and atomic force microscopy (AFM). Depending on the concentration and ratio of the components these nanowires can be micrometers long. These measurements further suggest that the aggregates adopt a helical conformation. The morphology of these nanowires are studied with fluorescent confocal laser scanning microscopy (CLSM). The interactions between LMWG and PTT are characterized by steady-state and time-resolved fluorescence spectroscopy studies. The steady-state spectra indicate that the backbone of the PTT adopts a more planar and more aggregated conformation when interacting with LMWG. The time-resolved fluorescence decay studies confirm this interpretation.
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| 5117. |
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| 5118. |
- Li, F., et al.
(författare)
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Simultaneous oxidation of alcohols and hydrogen evolution in a hybrid system under visible light irradiation
- 2018
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Ingår i: Applied Catalysis B. - : Elsevier B.V.. - 0926-3373 .- 1873-3883. ; 225, s. 258-263
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Tidskriftsartikel (refereegranskat)abstract
- Water oxidation as a multi-electron transfer and endothermal reaction has been considered to be the bottleneck of solar-driven water splitting into oxygen and hydrogen. Herein, an alternative approach for solar energy conversion is developed by coupling H2 generation with the selective oxidation of alcohol. In a closed redox system containing molecular ruthenium catalyst (RuCat) and Pt modified g-C3N4 (Pt-g-C3N4) composite, hydrogen production is concomitant with the oxidation of benzyl alcohols to aldehydes with over 99% selectivity in the presence of visible light and pure water. By contrary, the system lacking molecular catalyst only exhibits low to moderate selectivities towards aldehydes. The remarkably improved selectivity is attributed to the formation of highly active Ru(IV) = O intermediate through efficient hole transfer from g-C3N4 to RuCat.
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| 5119. |
- Li, F., et al.
(författare)
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Visible light-driven oxygen evolution using a binuclear Ru-bda catalyst
- 2018
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Ingår i: Cuihuà xuébào. - : Science Press. - 0253-9837 .- 1872-2067. ; 39:3, s. 446-452
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Tidskriftsartikel (refereegranskat)abstract
- Binuclear ruthenium complexes bearing the 2,2'-bipyridine-6,6'-dicarboxylate (bda) ligand have been demonstrated to be highly active catalysts towards water oxidation with CeIV as an oxidant. However, the catalytic properties of ruthenium dimers have not yet been explored for visible light-driven water oxidation. Herein, the photocatalytic performance of a dipyridyl propane-bridged ruthenium dimer 2 was investigated in comparison with its monomeric precursor, [Ru(bda)(pic)2] (1), in CH3CN/phosphate buffer mixed solvent in a three-component system including a photosensitizer and a sacrificial electron acceptor. Experimental results showed that the activity of each catalyst was strongly dependent on the content of CH3CN in the phosphate buffer, which not only affected the driving force for water oxidation, but also altered the kinetics of the reaction, probably through different mechanisms associated with the O–O bond formation. As a result, dimer 2 showed significantly higher activity than monomer 1 in the solvent containing a low content of CH3CN, and comparable activities were attained with a high content of CH3CN in the solvent. Under the optimal conditions, complex 2 achieved a turnover number of 638 for photocatalytic O2 evolution.
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| 5120. |
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