| 1. |
- Anugwom, Ikenna, et al.
(author)
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Switchable ionic liquids as delignification solvents for lignocellulosic materials
- 2014
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In: ChemSusChem. - : John Wiley & Sons. - 1864-5631 .- 1864-564X. ; 7:4, s. 1170-1176
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Journal article (peer-reviewed)abstract
- The transformation of lignocellulosic materials into potentially valuable resources is compromised by their complicated structure. Consequently, new economical and feasible conversion/fractionation techniques that render value-added products are intensely investigated. Herein an unorthodox and feasible fractionation method of birch chips (B. pendula) using a switchable ionic liquid (SIL) derived from an alkanol amine (monoethanol amine, MEA) and an organic super base (1,8-diazabicyclo-[5.4.0]-undec-7-ene, DBU) with two different trigger acid gases (CO2 and SO2 ) is studied. After SIL treatment, the dissolved fractions were selectively separated by a step-wise method using an antisolvent to induce precipitation. The SIL was recycled after concentration and evaporation of anti-solvent. The composition of undissolved wood after MEA-SO2 -SIL treatment resulted in 80 wt % cellulose, 10 wt % hemicelluloses, and 3 wt % lignin, whereas MEA-CO2 -SIL treatment resulted in 66 wt % cellulose, 12 wt % hemicelluloses and 11 wt % lignin. Thus, the MEA-SO2 -SIL proved more efficient than the MEA-CO2 -SIL, and a better solvent for lignin removal. All fractions were analyzed by gas chromatography (GC), Fourier transform infrared spectroscopy (FT-IR), (13) C nuclear magnetic resonance spectroscopy (NMR) and Gel permeation chromatography (GPC).
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| 2. |
- Baltrusaitis, J., et al.
(author)
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Photoelectrochemical Hydrogen Production on alpha-Fe2O3 (0001): Insights from Theory and Experiments
- 2014
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 7:1, s. 162-171
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Journal article (peer-reviewed)abstract
- The photoelectrochemical (PEC) decomposition of organic compounds in wastewater is investigated by using quantum chemical (DFT) methods to evaluate alternatives to water splitting for the production of renewable and sustainable hydrogen. Methanol is used as a model organic species for the theoretical evaluations of electrolysis on the surface of the widely available semiconductor hematite, alpha-Fe2O3, a widely studied photocatalyst. Three different alpha-Fe2O3 surface terminations were investigated, including the predominant surface found in aqueous electrolytes, (OH)(3)-R. The PEC oxidation of methanol is energetically downhill, producing CO2 and protons. The protons are reduced to hydrogen on the cathode. Experimental PEC measurements were also performed for several polyalcoholic compounds, glycerol, erythritol, and xylitol, on alpha-Fe2O3 as the photocatalyst and showed high incident-photon-to-current-efficiencies (IPCE) that were much greater than those of water splitting. Interestingly, high IPCEs were observed for hydrogen production from polyalcohols in the absence of any applied bias, which was not thought to be possible on hematite. These results support the potential application of PEC for hydrogen production by using widely available hematite for the PEC oxidation of selected components of organic wastewater present in large quantities from anthropogenic and industrial sources.
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| 3. |
- Chen, Cheng, et al.
(author)
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Degradation of Cyanoacrylic Acid-Based Organic Sensitizers in Dye-Sensitized Solar Cells
- 2013
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In: ChemSusChem. - : Wiley-VCH Verlagsgesellschaft. - 1864-5631 .- 1864-564X. ; 6:7, s. 1270-1275
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Journal article (peer-reviewed)abstract
- Organic dyes have become widely used in dye-sensitized solar cells (DSSCs) because of their good performance, flexible structural modifications, and low costs. To increase the photostability of organic dye-based DSSCs, we conducted a full study on the degradation mechanism of cyanoacrylic acid-based organic sensitizers in DSSCs. The results showed that with the synergy between water and UV light, the sensitizer could desorb from the TiO2 surface and the cyanoacrylic acid unit of the sensitizer was transformed into the aldehyde group. It was also observed that the water content had a great effect on the degradation process. Our experiments conducted using O-18-labeled water demonstrated that the oxygen atom of the aldehyde group identified in the degraded dye came from the solvent water in the DSSCs. Therefore, controlling the water content during DSSC fabrication, good sealing of cells, and filtering the UV light are crucial to produce DSSCs that are more durable and robust.
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| 4. |
- Cheng, Ming, et al.
(author)
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Efficient Organic Dye-Sensitized Solar Cells : Molecular Engineering of Donor-Acceptor-Acceptor cationic dyes
- 2013
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 6:12, s. 2322-2329
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Journal article (peer-reviewed)abstract
- Three metal-free donor-acceptor-acceptor sensitizers with ionized pyridine and a reference dye were synthesized, and a detailed investigation of the relationship between the dye structure and the photophysical and photoelectrochemical properties and the performance of dye-sensitized solar cells (DSSCs) is described. The ionization of pyridine results in a red shift of the absorption spectrum in comparison to that of the reference dye. This is mainly attributable to the ionization of pyridine increasing the electron-withdrawing ability of the total acceptor part. Incorporation of the strong electron-withdrawing units of pyridinium and cyano acrylic acid gives rise to optimized energy levels, resulting in a large response range of wavelengths. When attached to TiO2 film, the conduction band of TiO2 is negatively shifted to a different extent depending on the dye. This is attributed to the electron recombination rate between the TiO2 film and the electrolyte being efficiently suppressed by the introduction of long alkyl chains and thiophene units. DSSCs assembled using these dyes show efficiencies as high as 8.8%.
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| 5. |
- Galkin, Maxim, et al.
(author)
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Selective Route to 2-Propenyl Aryls Directly from Wood by a Tandem Organosolv and Palladium-Catalysed Transfer Hydrogenolysis
- 2014
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 7:8, s. 2154-2158
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Journal article (peer-reviewed)abstract
- A tandem organosolv pulping and Pd-catalysed transfer hydrogenolysis depolymerisation and deoxygenation has been developed. The tandem process generated 2-methoxy-4-(prop-1-enyl)phenol in 23 % yield (92 % theoretical monomer yield) starting from pine wood and 2,6-dimethoxy-4-(prop-1-enyl)phenol in 49 % yield (92 % theoretical monomer yield) starting from birch wood. Only endogenous hydrogen from wood was consumed, and the reaction was performed using green solvents.
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| 6. |
- Hao, Wenming, et al.
(author)
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Iron Oxide Nanoparticles Embedded in Activated Carbons Prepared from Hydrothermally Treated Waste Biomass
- 2014
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 7:3, s. 875-882
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Journal article (peer-reviewed)abstract
- Particles of iron oxide (Fe3O4; 20-40nm) were embedded within activated carbons during the activation of hydrothermally carbonized (HTC) biomasses in a flow of CO2. Four different HTC biomass samples (horse manure, grass cuttings, beer production waste, and biosludge) were used as precursors for the activated carbons. Nanoparticles of iron oxide formed from iron catalyst included in the HTC biomasses. After systematic optimization, the activated carbons had specific surface areas of about 800m(2)g(-1). The pore size distributions of the activated carbons depended strongly on the degree of carbonization of the precursors. Activated carbons prepared from highly carbonized precursors had mainly micropores, whereas those prepared from less carbonized precursors contained mainly mesopores. Given the strong magnetism of the activated carbon-nano-Fe3O4 composites, they could be particularly useful for water purification.
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| 7. |
- Hao, Yan, et al.
(author)
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Molecular Design to Improve the Performance of Donor-p Acceptor Near-IR Organic Dye-Sensitized Solar Cells
- 2011
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In: ChemSusChem. - : Wiley-Blackwell. - 1864-5631 .- 1864-564X. ; 4:11, s. 1601-1605
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Journal article (peer-reviewed)abstract
- Near-dye experience: Long, flexible carbon chains in the lateral anchoring groups of the donor part of a donor-π acceptor organic dye increase the power conversion efficiency dramatically. This performance enhancement can be ascribed to the prevention of the formation of molecular aggregates on the semiconductor nanoparticles, resulting in a lower recombination rate between transported electrons and I3- ions. A cell based on the new dye, HY113, gives a maximum IPCE value of 93% at 660nm.
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| 8. |
- Kirilin, Alexey V, et al.
(author)
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Reaction products and transformations of intermediates in the aqueous-phase reforming of sorbitol
- 2010
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In: ChemSusChem. - Weinheim : WILEY-VCH Verlag GmbH & Co. KGaA. - 1864-564X .- 1864-5631. ; 3:6, s. 708-718
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Journal article (peer-reviewed)abstract
- Aqueous phase reforming of sorbitol over Pt supported on an alumina catalyst is investigated, in order to identify the intermediates involved in the transformation of the initial feed. Parameters such as the sorbitol feed rate and temperature are studied. To identify the intermediates, an approach based on analysis of the gas and liquid phases as well as the total carbon content was developed. According to analysis by gas chromatography combined with mass spectrometry of volatile substances collected with solid-phase microextraction, over 260 compounds are involved in the transformation of sorbitol. Of these, 50 of the major products are identified with high reliability. It is shown that a great variety of compounds, bearing different functionalities, form part of the reaction network. The formation of the majority of identified compounds is explained and a reaction network for the formation of sorbitol and intermediate molecules transformation is proposed.
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| 9. |
- Li, Guoqiang, et al.
(author)
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Activity of Platinum/Carbon and Palladium/Carbon Catalysts Promoted by Ni2P in Direct Ethanol Fuel Cells
- 2014
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 7:12, s. 3374-3381
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Journal article (peer-reviewed)abstract
- Ethanol is an alternative fuel for direct alcohol fuel cells, inwhich the electrode materials are commonly based on Pt orPd. Owing to the excellent promotion effect of Ni2P that wasfound in methanol oxidation, we extended the catalyst systemof Pt or Pd modified by Ni2P in direct ethanol fuel cells. TheNi2P-promoted catalysts were compared to commercial catalystsas well as to reference catalysts promoted with only Ni oronly P. Among the studied catalysts, Pt/C and Pd/C modifiedby Ni2P (30 wt%) showed both the highest activity and stability.Upon integration into the anode of a homemade direct ethanolfuel cell, the Pt-Ni2P/C-30% catalyst showed a maximumpower density of 21 mWcm-2, which is approximately twotimes higher than that of a commercial Pt/C catalyst. The Pd-Ni2P/C-30% catalyst exhibited a maximum power density of90 mWcm-2. This is approximately 1.5 times higher than thatof a commercial Pd/C catalyst. The discharge stability on bothtwo catalysts was also greatly improved over a 12 h dischargeoperation.
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| 10. |
- Li, Hairong, et al.
(author)
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Comparative Studies on Rigid pi Linker-Based Organic Dyes : Structure-Property Relationships and Photovoltaic Performance
- 2014
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 7:12, s. 3396-3406
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Journal article (peer-reviewed)abstract
- A series of six structurally correlated donor-pi bridge-acceptor organic dyes were designed, synthesized, and applied as sensitizers in dye-sensitized solar cells. Using the most widely studied donor (triarylamine) and cyclopenta[1,2-b:5,4-b’]dithiophene or cyclopenta[1,2-b: 5,4-b’] dithiophene[2’,1’:4,5]thieno[2,3-d] thiophene as pi spacers, their structure-property relationships were investigated in depth by photophysical techniques and theoretical calculations. It was found that the photovoltaic performance of these dyes largely depends on their electronic structures, which requires synergistic interaction between donors and acceptors. Increasing the electron richness of the donor or the elongation of pi-conjugated bridges does not necessarily lead to higher performance. Rather, it is essential to rationally design the dyes by balancing their light-harvesting capability with achieving suitable energy levels to guarantee unimpeded charge separation and transport.
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