Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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The A-D-A type small molecules with isomeric benzodithiophene cores: Synthesis and influence of isomers on photoelectronic properties
No full textTwo isomeric A-D-A type small molecules (SMs) of BDTx-2TVTDPP and BDTy-2TVTDPP were designed and synthesized, which contain different donor (D) center of substituted benzodithiophene (BDT) in backbone, and the same acceptor (A) and bridged units of diketopyrrolopyrrole (DPP) and thienylene-vinylenethiophene (TVT), respectively. Their thermal stability, crystallinity, film morphology and photoelectronic properties were primarily investigated. It was found the BDTx-2TVTDPP with 2,6 substituted BDT unit exhibited a pronouncedly red-shifted and enhanced absorption in solid state and a better crystallinity. In contrast, the BDTy-2TVTDPP with 4,8-substituted BDT unit in backbone exhibited better solubility, deeper HOMO energy level and more smoothed blend film morphology. As a result, the solution-processing BDTy-2TVTDPP based solar cells displayed better photovoltaic properties than the BDTx-2TVTDPP based ones using fullerene derivatives (PC61BM or PC71BM) as electron acceptor. A power conversion efficiency maximum of 2.85% was obtained in the BDTy-2TV1DPP based cells, which is 1.8 times that of the BDTx-2TVTDPP based cells. This study indicates that changing the substituted positions of BDT is available to significantly improve photovoltaic properties for its resulting SMs. (C) 2016 Elsevier Ltd. All rights reserved
Superior performance of freeze-dried Ni/ZnO-Al2O3 adsorbent in the ultra-deep desulfurization of high sulfur model gasoline
No full textReactive adsorption desulfurization (RADS) is an effective approach to the ultra-deep desulfurization under mild conditions. The sulfur adsorption capacity of the adsorbents strongly depends on the pore structure, the chemical states and the dispersion of active species. In this work, ZnO-Al2O3 mixed oxides with an improved structure were synthesized via a freeze-drying modified cation-anion double hydrolysis (CADH) technique and used as the support. The fresh and spent catalysts were characterized through N-2 adsorption-desorption, H-2-temperature programmed reduction, X-ray diffraction, UV-vis diffuse reflection spectroscopy, Fourier transformed infrared spectroscopy and transmission electron microscopy (TEM). Freeze drying technique provided the adsorbent with a smaller sized ZnO and an improved pore structure compared with the normal oven drying method. Evaluation results in the RADS of a high sulfur model gasoline reveals that the freeze-dried Ni/ZnO-Al2O3 (40 degrees C) with a crystallization temperature of 40 degrees C exhibits a superior RADS performance with an accumulative sulfur adsorption capacity of 90 mg S/g, which is 53% and 118% higher than those of adsorbents prepared by the normal oven drying and the conventional kneading methods. A high amount of small ZnO particles, improved textural properties and the absence of inactive NiAl2O4 phase are among the factors accounting for the superior RADS performance of Ni/ZnO-Al2O3 adsorbent prepared by the freeze-drying method. Upon four RADS-regeneration cycles, sample Ni/ZnO-Al2O3 (40 degrees C) exhibited a high stability without evident activity loss. (C) 2016 Elsevier B.V. All rights reserved
Modulation of the Acetone/Butanol Ratio during Fermentation of Corn StoverDerived Hydrolysate by Clostridium beijerinckii Strain NCIMB 8052
No full textProducing biobutanol from lignocellulosic biomass has shown promise to ultimately reduce greenhouse gases and alleviate the global energy crisis. However, because of the recalcitrance of a lignocellulosic biomass, a pretreatment of the substrate is needed which in many cases releases soluble lignin compounds (SLCs), which inhibit growth of butanol-producing clostridia. In this study, we found that SLCs changed the acetone/butanol ratio (A/B ratio) during butanol fermentation. The typical A/B molar ratio during Clostridium beijerinckii NCIMB 8052 batch fermentation with glucose as the carbon source is about 0.5. In the present study, the A/B molar ratio during batch fermentation with a lignocellulosic hydrolysate as the carbon source was 0.95 at the end of fermentation. Structural and redox potential changes of the SLCs were characterized before and after fermentation by using gas chromatography/mass spectrometry and electrochemical analyses, which indicated that some exogenous SLCs were involved in distributing electron flow to C. beijerinckii, leading to modulation of the redox balance. This was further demonstrated by the NADH/NAD(+) ratio and trxB gene expression profile assays at the onset of solventogenic growth. As a result, the A/B ratio of end products changed significantly during C. beijerinckii fermentation using corn stover-derived hydrolysate as the carbon source compared to glucose as the carbon source. These results revealed that SLCs not only inhibited cell growth but also modulated the A/B ratio during C. beijerinckii butanol fermentation
One-Step Synthesis of Biodegradable Polyurethane Prepolymer and Its Rapid Gelation Behavior at High Water Content
No full textIn this study, a very simple, scalable, and low-cost one-step recipe is presented for preparing a biodegradable polyurethane prepolymer composed of isocyanate terminated linear polyethylene glycol and isocyanate terminated four-armed polycaprolactone. Then, the corresponding hydrogels are easily formed by mixing the prepolymer with water in few minutes. The resulting hydrogel shows excellent mechanical properties with high tensile strength (up to 233.6 KPa) and recorded elongation rate (5000%), while maintaining high water content (up to 91% mass ratio). Meanwhile, the maximum water retaining capacity of the hydrogel can be up to 40 times of polyurethane prepolymer (in mass), which is equal to 97.6% water content. In addition, the degradation properties of the obtained hydrogel are studied in detail. This study demonstrates a facile approach to prepare the hydrogel with both excellent mechanical properties and high water content, which marks it as a potential candidate for applications in agrological field, such as sand fixing in desertification control
An alpha-CrPO4-type NaV3(PO4)(3) anode for sodium-ion batteries with excellent cycling stability and the exploration of sodium storage behavior
No full textA novel alpha-CrPO4-type vanadium-based orthophosphate NaV3(PO4)(3) was synthesized as a promising anode material for Na-ion batteries, which exhibits a high reversible capacity of 140 mA h g(-1) with the capacity retention about 98% after 100 cycles. Furthermore, the electrochemical reaction mechanism, structure evolution and ionic diffusion of NaV3(PO4)(3) during the sodiation process were surveyed by the combination of experiments and first-principles calculations. Two different Wyckoff sites (4b, Na2 and 4c, Na3) which can accommodate more sodium ions, as well as the corresponding Na insertion process were reported to understand the sodium storage mechanism in NaV3(PO4)(3). The 3d-electron distribution near the Fermi level for vanadium in different valence states and sites (4a and 8g) in NaxV3(PO4)(3) (x = 1, 2, 3) and the local electron transfer during the sodiation process were described to predict the transition of the electrochemical properties. The cooperative-transport mechanism dominates the Na diffusion in NaxV3(PO4)(3) (1 <= x <= 3) and the activation barrier for Na+ transport in Na1.125V3(PO4)(3) (0.30 eV) is much lower than that in NaV3(PO4)(3) (1.28 eV), suggesting the fast-ion transport characteristics during the sodiation process and the strong stability of Na at the 4e site
The Influence of Alkali Treatment for Synthesizing Hierarchical Zeolite on Behavior of Cobalt Fischer-Tropsch Synthesis Catalysts
No full textHierarchical zeolites were synthesized by alkali treatment and their applications in Fischer-Tropsch (FT) synthesis were studied. It was found that alkali treatment not only created hierarchical structure but also could tune cobalt-support interaction. The dissolution of Si by alkali treatment became easier with the increase of Si/Al ratio, and thus the amount of mesopority increased. An optimal Si/Al molar ratio was identified over the zeolite with Si/Al ratio of 80, which was found to be superior to other catalysts in terms of better diesel selectivity and lower CH4 selectivity due to its relatively narrow bimodal pore size distribution and moderate cobalt-support interaction. Meanwhile alkali treatment could enhance cobalt-support interaction via the formation of E-SiO2, Co/MZ-120 catalyst showed the lowest FT activity and higher CH4 selectivity due to the increase of such new phase
High-voltage and free-standing poly(propylene carbonate)/Li6.75La3Zr1.75Ta0.25O12 composite solid electrolyte for wide temperature range and flexible solid lithium ion battery
No full textSolid electrolyte is regarded as a perfect way to enhance safety issues and boost energy density of lithium batteries. Herein, we developed a type of free-standing poly(propylene carbonate)/Li6.75La3Zr1.75Ta0.25O12 composite solid electrolyte for ambient temperature and flexible solid-state lithium batteries. The composite solid electrolyte exhibited excellent comprehensive performance in terms of high ionic conductivity (5.2 x 10(-4) S cm(-1)) at 20 degrees C, a wide electrochemical window (4.6 V), high ionic transference number (0.75) and satisfactory mechanical strength (6.8 MPa). When evaluated as solid electrolyte for an ambient-temperature solid lithium battery, such a composite electrolyte delivered excellent rate capability (5C) at 20 degrees C. This superior performance can be comparable to a liquid electrolyte-soaked PP separator-based lithium battery at room temperature. To our knowledge, this is the best rate capability of a solid composite electrolyte for a solid lithium battery at ambient temperature. Moreover, such a composite electrolyte-based flexible LiFePO4/Li4Ti5O12 lithium ion battery delivered excellent rate capability and superior cycling stability. All these fascinating features make poly(propylene carbonate)/Li6.75La3Zr1.75Ta0.25O12 a very promising all-solid-state electrolyte for flexible solid lithium batteries. Our study makes a big step into addressing the challenges of ambient-temperature solid lithium batteries
Hydrogen bond dynamics governs the effective photoprotection mechanism of plant phenolic sunscreens
No full textSinapic acid derivatives are important sunscreen species in natural plants, which could provide protection from solar UV radiation. Using a combination of ultrafast excited state dynamics, together with classical molecular dynamics studies, we demonstrate that there is direct coupling of hydrogen bond motion with excited state photoprotection dynamics as part of the basic mechanism in solution. Beyond the intramolecular degree of freedom, the inter-molecular motions on all timescales are potentially important for the photochemical or photophysical events, ranging from the ultrafast hydrogen bond motion to solvent rearrangements. This provides not only an enhanced understanding of the anomalous experimental spectroscopic results, but also the key idea in the development of sunscreen agents with improved photo-chemical properties. We suggest that the hydrogen bond dynamics coupled excited state photoprotection mechanism may also be possible in a broad range of bio-related molecules in the condensed phase
Malonyl-CoA pathway: a promising route for 3-hydroxypropionate biosynthesis
No full text3-Hydroxypropionate (3HP) is an attractive platform chemical, serving as a precursor to a variety of commodity chemicals like acrylate and acrylamide, as well as a monomer of a biodegradable plastic. To establish a sustainable way to produce these commercially important chemicals and materials, fermentative production of 3HP is widely investigated in recent years. It is reported that 3HP can be produced from several intermediates, such as glycerol, malonyl-CoA, and beta-alanine. Among all these biosynthetic routes, the malonyl-CoA pathway has some distinct advantages, including a broad feedstock spectrum, thermodynamic feasibility, and redox neutrality. To date, this pathway has been successfully constructed in various species including Escherichia coli, yeast and cyanobacteria, and optimized through carbon flux redirection, enzyme screening and engineering, and an increasing supply of energy and cofactors, resulting in significantly enhanced 3HP titer up to 40 g/L. These results show the feasibility of commercial manufacturing of 3HP and its derivatives in the future
Reduced Polysulfide Shuttle Effect by Using Polyimide Separators with Ionic Liquid-based Electrolytes in Lithium-Sulfur Battery
No full textIn this research, we demonstrate a new method for reducing the shuttle effect by confining polysulfide in separator area through the use of polyimide (PI) separator with reversible adsorption functions in lithium-sulfur batteries. As a comparison, the cells with polypropylene (PP) separators which have no function to adsorb dissoluble polysulfide show a result that the content of sulfur on lithium anode surface is increased up to 63.94% after 100th cycles with the content of N-methyl-N-butylpiperidinium bis(trifluoromethylsulfonyl) imide (PP14TFSI) in the mixture electrolyte increasing. This result illustrates that the migration and reaction between dissolved polysulfide in PP14TFSI and lithium cannot be neglected although the solubility of polysulfide is slight in PP14TFSI solvent. However, when PI separators are introduced, besides improving the wettability with PP14TFSI-based electrolytes, experimental results also show that the PI separator has a reversible adsorption function to dissoluble polysulfide which is used to confining polysulfide in separator area to a certain extent due to the abundant nitrogen-, oxygen-containing functional groups in PI skeleton. What's more, PI separator can decreases the sulfur content on lithium surface after cycling to 17.92% which decreases greatly than that with PP separator and improves its electrochemical performance. (C) 2017 Elsevier Ltd. All rights reserved