| 1. |
- Duan, Lele, et al.
(författare)
-
Ce-IV- and Light-Driven Water Oxidation by [Ru(terpy)(pic)(3)](2+) Analogues : Catalytic and Mechanistic Studies
- 2011
-
Ingår i: CHEMSUSCHEM. - : Wiley. - 1864-5631. ; 4:2, s. 238-244
-
Tidskriftsartikel (refereegranskat)abstract
- A series of mononuclear ruthenium polypyridyl complexes [Ru(Mebimpy)(pic)(3)](PF6)(2) (2; Mebimpy=2,6-bis(1-methylbenzimidazol-2-yl)pyridine; pic=4-picoline), Ru(bimpy)(pic)(3) (3; H(2)bimpy=2,6-bis(benzimidazol-2-yl)pyridine), trans-[Ru(terpy)-(pic)(2)Cl](PF6) (4; terpy=2,2';6',2 ''-terpyridine), and trans-[Ru(terpy)(pic)(2)(OH2)](ClO4)(2) (5) are synthesized and characterized as analogues of the known Ru complex, [Ru(terpy)(pic)(3)](PF6)(2) (1). The effect of the ligands on electronic and catalytic properties is studied and discussed. The negatively charged ligand, bimpy(2-), has a remarkable influence on the electrochemical events due to its strong electron-donating ability. The performance in light- and Ce-IV-driven (Ce-IV=Ce(NH4)(2)(NO3)(6)) water oxidation is successfully demonstrated. We propose that ligand exchange between pic and H2O occurs to form the real catalyst, a Ru-aqua complex. The synthesis and testing of trans[Ru(terpy)(pic)(2)(OH2)](ClO4)(2) (5) confirmed our proposal. In addition, complex 5 possesses the best catalytic activity among these five complexes.
|
|
| 2. |
- Duan, Lele, et al.
(författare)
-
Chemical and Photochemical Water Oxidation Catalyzed by Mononuclear Ruthenium Complexes with a Negatively Charged Tridentate Ligand
- 2010
-
Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 16:15, s. 4659-4668
-
Tidskriftsartikel (refereegranskat)abstract
- Two mononuclear ruthenium complexes [RuL(pic)(3)] (1) and [RuL(bpy)(pic)] (2) (H2L = 2,6-pyridinedicarboxylic acid, pic=4-picoline, bpy = 2,2'-bipyridine) have been synthesized and fully characterized. Both complexes could promote water oxidation chemically and photochemically. Compared with other known ruthenium-based water oxidation catalysts using [Ce(NH4)(2)(NO3)(6)] (Ce-IV) as the oxidant in solution at pH 1.0, complex 1 is one of the most active catalysts yet reported with an initial rate of 0.23 turnovers(-1). Under acidic conditions, the equatorial 4-picoline in complex 1 dissociates first. In addition, ligand exchange in 1 occurs when the Rum state is reached. Based on the above observations and MS measurements of the intermediates during water oxidation by 1 using Ce-IV as oxidant, [RuL(pic)(2)(H2O)](+) is proposed as the real water oxidation catalyst.
|
|
| 3. |
- Duan, Lele, et al.
(författare)
-
Visible Light-Driven Water Oxidation by a Molecular Ruthenium Catalyst in Homogeneous System
- 2010
-
Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 49:1, s. 209-215
-
Tidskriftsartikel (refereegranskat)abstract
- Discovery of an efficient catalyst bearing low overpotential toward water oxidation is a key step for light-driven water splitting into dioxygen and dihydrogen. A mononuclear ruthenium complex, Ru(II)L(pic)(2) (1) (H2L = 2,2'-bipyridine-6,6'-dicarboxylic acids pic = 4-picoline), was found capable of oxidizing water eletrochemically at a relatively low potential and promoting light-driven water oxidation using a three-component system composed of a photosensitizer, sacrificial electron acceptor, and complex 1. The detailed electrochemical properties of 1 were studied, and the onset potentials of the electrochemically catalytic curves in pH 7.0 and pH 1.0 solutions are 1.0 and 1.5 V, respectively. The low catalytic potential of 1 under neutral conditions allows the use of [Ru(bpy)(3)](2+) and even [Ru(dmbpy)(3)](2+) as a photosensitizer for photochemical water oxidation. Two different sacrificial electron acceptors, [Co(NH3)(5)Cl]Cl-2 and Na2S2O8, were used to generate the oxidized state of ruthenium tris(2,2'-bipyridyl) photosensitizers. In addition, a two-hour photolysis of I in a pH TO phosphate buffer did not lead to obvious degradation, indicating the good photostability of our catalyst. However, under conditions of light-driven water oxidation, the catalyst deactivates quickly. In both solution and the solid state under aerobic conditions, complex 1 gradually decomposed via oxidative degradation of its ligands, and two of the decomposed products, sp(3) C-H bond oxidized Ru complexes, were identified. The capability of oxidizing the sp(3) C-H bond implies the presence of a highly oxidizing Ru species, which might also cause the final degradation of the catalyst.
|
|
| 4. |
- Duan, Lele, et al.
(författare)
-
Visible light-driven water oxidation-from molecular catalysts to photoelectrochemical cells
- 2011
-
Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 4:9, s. 3296-3313
-
Tidskriftsartikel (refereegranskat)abstract
- This perspective article reports the most significant advances in the field of water oxidation-from molecular water oxidation catalysts (WOCs) to photoelectrochemical cells. Different series of catalysts that can be applied in visible light-driven water oxidation catalysis are discussed in details and several key aspects of their catalytic mechanisms are introduced. In order to construct a water oxidation electrode from molecular catalysts, proper immobilization methods have to be employed. Herein, we present one section about how to attach catalysts onto an electrode/material surface. Finally, the state of the art photoelectrochemical cells that achieve visible light-driven water splitting are described.
|
|
| 5. |
- Huang, Jing, et al.
(författare)
-
Improved Performance of Colloidal CdSe Quantum Dot-Sensitized Solar Cells by Hybrid Passivation
- 2014
-
Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 6:21, s. 18808-18815
-
Tidskriftsartikel (refereegranskat)abstract
- A hybrid passivation strategy is employed to modify the surface of colloidal CdSe quantum dots (QDs) for quantum dot-sensitized solar cells (QDSCs), by using mercaptopropionic acid (MPA) and iodide anions through a ligand exchange reaction in solution. This is found to be an effective way to improve the performance of QDSCs based on colloidal QDs. The results show that MPA can increase the coverage of the QDs on TiO2 electrodes and facilitate the hole extraction from the photoxidized QDs, and simultaneously, that the iodide anions can remedy the surface defects of the CdSe QDs and thus reduce the recombination loss in the device. This hybrid passivation treatment leads to a significant enhancement of the power conversion efficiency of the QDSCs by 41%. Furthermore, an optimal ratio of iodide ions to MPA was determined for favorable hybrid passivation; results show that excessive iodine anions are detrimental to the loading of the QDs. This study demonstrates that the improvement in QDSC performance can be realized by using a combination of different functional ligands to passivate the QDs, and that ligand exchange in solution effective approach to introduce can be an different ligands.
|
|
| 6. |
|
|
| 7. |
- Pettersson, Henrik, et al.
(författare)
-
Parallel-connected monolithic dye-sensitised solar modules
- 2010
-
Ingår i: Progress in Photovoltaics. - : Wiley. - 1062-7995 .- 1099-159X. ; 18:5, s. 340-345
-
Tidskriftsartikel (refereegranskat)abstract
- Light-soaking and high-temperature storage testing of monolithic dye-sensitised solar modules with total area module efficiencies above 5% have been performed. Our experiences from the development of a four-layer monolithic dye-sensitised solar test cell for comparative testing of material components for dye-sensitised solar cells have directed our module development to a novel device design consisting of parallel-connection of individual monolithic cells. The results from the accelerated testing of the modules (total area of 17.0 cm(2)) with four parallel-connected cells (active area of 3.38 cm(2)/cell) are equivalent to those obtained for the monolithic single test cells when using identical device components. The successful transfer from cell to module stability is an important milestone in our ambition to develop a low-cost Photovoltaic (PV) technology. Moreover, our results indicate that intensified research and development to define the procedures for relevant accelerated testing of dye-sensitised solar modules is urgently required.
|
|
| 8. |
- Tian, Haining, et al.
(författare)
-
Effect of the chromophores structures on the performance of solid-state dye sensitized solar cells
- 2014
-
Ingår i: Nano. - 1793-2920. ; 9:5, s. 1440005-
-
Tidskriftsartikel (refereegranskat)abstract
- The er effect of metal-free chromophores on dye-sensitized solar cell performance is investigated. Solid state dye-sensitized solar cells (ssDSCs) using dirfferent molecular sensitizers based on tri-phenylamine (TPA) with thiophene linkers and different alkyl chain in the donor unit have been characterized using impedance spectroscopy (IS). We show that different molecular structures play a fundamental role on solar cell performance, by the effect produced on TiO2 conduction band position and in the recombination rate. Dye structure and its electronic properties are the main factors that control the recombination, the capacitance and the efficiency of the cells. A clear trend between the performance of the cell and the optimization level of the blocking effect of the dye structure has been identified in the solid state solar cells with Spiro-OMeTAD hole conductor.
|
|
| 9. |
- Tian, Haining, et al.
(författare)
-
Enhancement of p-Type Dye-Sensitized Solar Cell Performance by Supramolecular Assembly of Electron Donor and Acceptor
- 2014
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 4, s. 4282-
-
Tidskriftsartikel (refereegranskat)abstract
- Supramolecular interactions based on porphyrin and fullerene derivatives were successfully adopted to improve the photovoltaic performance of p-type dye-sensitized solar cells (DSCs). Photoelectron spectroscopy (PES) measurements suggest a change in binding configuration of ZnTCPP after co-sensitization with C60PPy, which could be ascribed to supramolecular interaction between ZnTCPP and C60PPy. The performance of the ZnTCPP/C60PPy-based p-type DSC has been increased by a factor of 4 in comparison with the DSC with the ZnTCPP alone. At 560 nm, the IPCE value of DSCs based on ZnTCPP/C60PPy was a factor of 10 greater than that generated by ZnTCPP-based DSCs. The influence of different electrolytes on charge extraction and electron lifetime was investigated and showed that the enhanced V-oc from the Co2+/(3+)(dtbp)(3)-based device is due to the positive E-F shift of NiO.
|
|
| 10. |
|
|
