| 21. |
- Chen, C., et al.
(författare)
-
Boosting Electrocatalytic Water Oxidation by Creating Defects and Lattice-Oxygen Active Sites on Ni-Fe Nanosheets
- 2020
-
Ingår i: ChemSusChem. - : Wiley-VCH Verlag. - 1864-5631 .- 1864-564X. ; 13:18, s. 5067-5072
-
Tidskriftsartikel (refereegranskat)abstract
- Layered nickel-iron oxide/hydroxide nanosheets have proven to be the most efficient catalyst for the water oxidation reaction. Introducing structural defects to the nanosheets is a particularly attractive method for increasing the number of active sites and tailoring the intrinsic electronic properties. Herein, defects were introduced on Ni−Fe nanosheets through sequentially electrodoping and dedoping the surface of the material with tetramethylammonium ions. The as-prepared defect-rich Ni−Fe nanosheets showed an enhanced catalytic performance for the oxygen evolution reaction (OER) compared with conventional NiFe layered double hydroxides (LDHs), exhibiting an overpotential of only 172 mV at the current density of 10 mA cm−2. The relationship between pH and OER activity indicated that the lattice oxygens participated in the catalytic OER process as active sites. This work provides new insights into the understanding of the structure-activity relationship of layered materials and helps to develop new methods to implement defects on such frameworks aided by organic molecules.
|
|
| 22. |
- Chen, Cheng, et al.
(författare)
-
Degradation of Cyanoacrylic Acid-Based Organic Sensitizers in Dye-Sensitized Solar Cells
- 2013
-
Ingår i: ChemSusChem. - : Wiley-VCH Verlagsgesellschaft. - 1864-5631 .- 1864-564X. ; 6:7, s. 1270-1275
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 23. |
- Chen, Hu, et al.
(författare)
-
Highly Active Three-Dimensional NiFe/Cu2O Nanowires/Cu Foam Electrode for Water Oxidation
- 2017
-
Ingår i: ChemSusChem. - : Wiley-VCH Verlagsgesellschaft. - 1864-5631 .- 1864-564X. ; 10:7, s. 1475-1481
-
Tidskriftsartikel (refereegranskat)abstract
- Water splitting is of paramount importance for exploiting renewable energy-conversion and -storage systems, but is greatly hindered by the kinetically sluggish oxygen evolution reaction (OER). In this work, a three-dimensional, highly efficient, and durable NiFe/Cu2O nanowires/Cu foam anode (NiFe/Cu2O NWs/CF) for water oxidation in 1.0m KOH was developed. The obtained electrode exhibited a current density of 10mAcm(-2) at a uniquely low overpotential of =215mV. The average specific current density (j(s)) was estimated, on the basis of the electrocatalytically active surface area, to be 0.163mAcm(-2) at =310mV. The electrode also displayed a low Tafel slope of 42mVdecade(-1). Moreover, the NiFe/Cu2O NWs/CF electrode could maintain a steady current density of 100mAcm(-2) for 50h at an overpotential of =260mV. The outstanding electrochemical performance of the electrode for the OER was attributed to the high conductivity of the Cu foam and the specific structure of the electrode with a large interfacial area.
|
|
| 24. |
- Cheng, Ming, et al.
(författare)
-
Efficient Organic Dye-Sensitized Solar Cells : Molecular Engineering of Donor-Acceptor-Acceptor cationic dyes
- 2013
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 6:12, s. 2322-2329
-
Tidskriftsartikel (refereegranskat)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%.
|
|
| 25. |
- Cong, Jiayan, et al.
(författare)
-
Electrolytes Based on TEMPO-Co Tandem Redox Systems Outperform Single Redox Systems in Dye-sensitized Solar Cells
- 2015
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 8:2, s. 264-268
-
Tidskriftsartikel (refereegranskat)abstract
- A new TEMPO-Co tandem redox system with TEMPO and Co(bpy)(3)(2+/3+) has been investigated for the use in dye-sensitized solar cells (DSSCs). A large open-circuit voltage (V-OC) increase, from 862 mV to 965 mV, was observed in the tandem redox system, while the short-circuit current density (J(SC)) was maintained. The conversion efficiency was observed to increase from 7.1% for cells containing the single Co(bpy)(3)(2+/3+) redox couple, to 8.4% for cells containing the TEMPO-Co tandem redox system. The reason for the increase in V-OC and overall efficiency is ascribed to the involvement of partial regeneration of the sensitizing dye molecules by TEMPO. This assumption can be verified through the observed much faster regeneration dynamics exhibited in the presence of the tandem system. Using the tandem redox system, the faster recombination problem of the single TEMPO redox couple is resolved and the mass-transport of the metal-complex-based electrolyte is also improved. This TEMPO-Co tandem system is so far the most effienct tandem redox electrolyte reported not involving iodine. The current results show a promising future for tandem system as replacements for single redox systems in electrolytes for DSSCs.
|
|
| 26. |
- Das, Biswanath, et al.
(författare)
-
Iron Pentapyridyl Complexes as Molecular WaterOxidation Catalysts : Strong Influence of a Chloride Ligandand pH in Altering the Mechanism
- 2016
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 9:10, s. 1178-1186
-
Tidskriftsartikel (refereegranskat)abstract
- The development of molecular water oxidation catalysts basedon earth-abundant, non-noble metals is essential for artificial photosynthesis research. Iron, which is the most abundant transition metal in the earth's crust, is a prospective candidate for this purpose. Herein, we report two iron complexes based on the polypyridyl ligand Py5OH (Py5OH=pyridine-2,6-diylbis[di(pyridin-2-yl)methanol]) that can catalyse water oxidation to produce O2 in RuIII-induced (at pH 8, highest turnover number (TON)=26.5; turnover frequency (TOF)=2.2 s-1), CeIV-induced(at pH 1.5 highest TON=16; TOF=0.75 s-1) and photo-induced(at pH 8, highest TON=43.5; TOF=0.6 s-1) reactions. A chloride ligand in one of the iron complexes is shown to affect the activity strongly, improve stability and, thereby, the performance at pH 8 but it inhibits oxygen evolution at pH 1.5. The observations are consistent with a change in mechanism for catalytic water oxidation with the Fe(Py5OH) complexes between acidic (CeIV) and near-neutral pH (RuIII).
|
|
| 27. |
- Dau, H., et al.
(författare)
-
Artificial Photosynthesis : Beyond Mimicking Nature
- 2017
-
Ingår i: ChemSusChem. - : Wiley-VCH Verlagsgesellschaft. - 1864-5631 .- 1864-564X. ; 10:22, s. 4228-4235
-
Tidskriftsartikel (refereegranskat)abstract
- In this Editorial, Guest Editors Holger Dau, Etsuko Fujita, and Licheng Sun introduce the Special Issue of ChemSusChem on “Artificial Photosynthesis for Sustainable Fuels”. They discuss the need for non-fossil based fuels, introduce both biological and artificial photosynthesis, and outline various important concepts in artificial photosynthesis, including molecular and solid-state catalysts for water oxidation and hydrogen evolution, catalytic CO2 reduction, and photoelectrochemical systems.
|
|
| 28. |
- De Santi, Alessandra, et al.
(författare)
-
Lignin‐First Fractionation of Softwood Lignocellulose Using a Mild Dimethyl Carbonate and Ethylene Glycol Organosolv Process
- 2020
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 13:17, s. 4468-4477
-
Tidskriftsartikel (refereegranskat)abstract
- A mild lignin-first acidolysis process (140 °C, 40 min) was developed using the benign solvent dimethyl carbonate (DMC) and ethylene glycol (EG) as a stabilization agent/solvent to produce a high yield of aromatic monophenols directly from softwood lignocellulose (pine, spruce, cedar, and Douglas fir) with a depolymerization efficiency of 77–98 %. Under the optimized conditions (140 °C, 40 min, 400 wt % EG and 2 wt % H2SO4 to pinewood), up to 9 wt % of the aromatic monophenol was produced, reaching a degree of delignification in pinewood of 77 %. Cellulose was also preserved, as evidenced by a 85 % glucose yield after enzymatic digestion. An in-depth analysis of the depolymerization oil was conducted by using GC-MS, HPLC, 2 D-NMR, and size-exclusion chromatography, which provided structural insights into lignin-derived dimers and oligomers and the composition of the sugars and derived molecules. Mass balance evaluation was performed.
|
|
| 29. |
- Di Francesco, Davide, 1989-, et al.
(författare)
-
A New Family of Renewable Thermosets : Kraft Lignin Poly-adipates
- 2022
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 15:11
-
Tidskriftsartikel (refereegranskat)abstract
- Thermosetting polymeric materials have advantageous properties and are therefore used in numerous applications. In this study, it was hypothesized and ultimately shown that thermosets could be derived from comparably sustainable sub-components. A two-step procedure to produce a thermoset comprising of Kraft lignin (KL) and the cross-linker adipic acid (AdA) was developed. The cross-linking was activated by means of an acetylating agent comprising isopropenyl acetate (IPA) to form a cross-linking mixture (CLM). The cross-linking was confirmed by FTIR and solid-state NMR spectroscopy, and the esterification reactions were further studied using model compounds. When the KL lignin was mixed with the CLM, partial esterification occurred to yield a homogeneous viscous liquid that could easily be poured into a mold, as the first step in the procedure. Without any additions, the mold was heated and the material transformed into a thermoset by reaction of the two carboxylic acid-derivatives of AdA and KL in the second step.
|
|
| 30. |
- Di Francesco, Davide, et al.
(författare)
-
Debottlenecking a Pulp Mill by Producing Biofuels from Black Liquor in Three Steps
- 2021
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 14:11, s. 2414-2425
-
Tidskriftsartikel (refereegranskat)abstract
- By extracting lignin, pulp production can be increased without heavy investments in a new recovery boiler, the typical bottleneck of a pulp mill. The extraction is performed by using 0.20 and 0.15 weight equivalents of CO2 and H2SO4 respectively. Herein, we describe lignin esterification with fatty acids using benign reagents to generate a lignin ester mixable with gas oils. The esterification is accomplished by activating the fatty acid and lignin with acetic anhydride which can be regenerated from the acetic acid recycled in this reaction. The resulting mass balance ratio is fatty acid/lignin/acetic acid (2 : 1 : 0.1). This lignin ester can be hydroprocessed to generate hydrocarbons in gasoline, aviation, and diesel range. A 300-hour continuous production of fuel was accomplished. By recirculating reagents from both the esterification step and applying a water gas shift reaction on off-gases from the hydroprocessing, a favorable overall mass balance is realized.
|
|
