| 1. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Cai, Jing, et al.
(författare)
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Influence of organic aerosol molecular composition on particle absorptive properties in autumn Beijing
- 2022
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 22:2, s. 1251-1269
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Tidskriftsartikel (refereegranskat)abstract
- Organic aerosol (OA) is a major component of fine particulate matter (PM), affecting air quality, human health, and the climate. The absorptive and reflective behavior of OA components contributes to determining particle optical properties and thus their effects on the radiative budget of the troposphere. There is limited knowledge on the influence of the molecular composition of OA on particle optical properties in the polluted urban environment. In this study, we characterized the molecular composition of oxygenated OA collected on filter samples in the autumn of 2018 in Beijing, China, with a filter inlet for gases and aerosols coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (FIGAERO–CIMS). Three haze episodes occurred during our sampling period with daily maximum concentrations of OA of 50, 30, and 55 µg m−3. We found that the signal intensities of dicarboxylic acids and sulfur-containing compounds increased during the two more intense haze episodes, while the relative contributions of wood-burning markers and other aromatic compounds were enhanced during the cleaner periods. We further assessed the optical properties of oxygenated OA components by combining detailed chemical composition measurements with collocated particle light absorption measurements. We show that light absorption enhancement (Eabs) of black carbon (BC) was mostly related to more oxygenated OA (e.g., dicarboxylic acids), likely formed in aqueous-phase reactions during the intense haze periods with higher relative humidity, and speculate that they might contribute to lensing effects. Aromatics and nitro-aromatics (e.g., nitrocatechol and its derivatives) were mostly related to a high light absorption coefficient (babs) consistent with light-absorbing (brown) carbon (BrC). Our results provide information on oxygenated OA components at the molecular level associated with BrC and BC particle light absorption and can serve as a basis for further studies on the effects of anthropogenic OA on radiative forcing in the urban environment.
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| 3. |
- Cai, Jing, et al.
(författare)
-
Influence of organic aerosol molecular composition on particle absorptive properties in autumn Beijing
- 2022
-
Ingår i: Atmospheric Chemistry and Physics. - 1680-7316 .- 1680-7324. ; 22, s. 1251-1269
-
Tidskriftsartikel (refereegranskat)abstract
- Organic aerosol (OA) is a major component of fine particulate matter (PM), affecting air quality, human health, and the climate. The absorptive and reflective behavior of OA components contributes to determining particle optical properties and thus their effects on the radiative budget of the troposphere. There is limited knowledge on the influence of the molecular composition of OA on particle optical properties in the polluted urban environment. In this study, we characterized the molecular composition of oxygenated OA collected on filter samples in the autumn of 2018 in Beijing, China, with a filter inlet for gases and aerosols coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (FIGAERO-CIMS). Three haze episodes occurred during our sampling period with daily maximum concentrations of OA of 50, 30, and 55 μg m-3. We found that the signal intensities of dicarboxylic acids and sulfur-containing compounds increased during the two more intense haze episodes, while the relative contributions of wood-burning markers and other aromatic compounds were enhanced during the cleaner periods. We further assessed the optical properties of oxygenated OA components by combining detailed chemical composition measurements with collocated particle light absorption measurements. We show that light absorption enhancement (Eabs) of black carbon (BC) was mostly related to more oxygenated OA (e.g., dicarboxylic acids), likely formed in aqueous-phase reactions during the intense haze periods with higher relative humidity, and speculate that they might contribute to lensing effects. Aromatics and nitro-aromatics (e.g., nitrocatechol and its derivatives) were mostly related to a high light absorption coefficient (babs) consistent with light-absorbing (brown) carbon (BrC). Our results provide information on oxygenated OA components at the molecular level associated with BrC and BC particle light absorption and can serve as a basis for further studies on the effects of anthropogenic OA on radiative forcing in the urban environment. Copyright:
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| 4. |
- Fan, Jiandong, et al.
(författare)
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Cobalt(II/III) Redox Electrolyte in ZnO Nanowire-Based Dye-Sensitized Solar Cells
- 2013
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 5:6, s. 1902-1906
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we explore the use of cobalt complex redox shuttles in dye sensitized solar cells (DSCs) based on ZnO nanowires (NWs). Arrays of vertically aligned ZnO NWs produced by a low-cost hydrothermal method are used to fabricate DSCs with [Co(bpy)(3)](2+/3+) as electrolyte. A direct comparison of the performance of [Co(bpy)(3)](2+/3+)-based ZnO DSC with I-/I-3(-)-based ones demonstrates the higher suitability of the cobalt complex, both in terms of a larger open circuit voltage (V-OC) and a higher photocurrent. The [Co(bpy)(3)](2+/3+) electrolyte results in V-OC enhancements above 200 mV. This V-OC increase is associated to the better match between the cobalt complex redox potential and the oxidation potential of the dye. The incident photon-to-current efficiency (IPCE) enhancement is attributed to a less competitive visible light absorption of the cobalt redox couple. Thus the present study opens new opportunities to improve energy conversion efficiency in ZnO-based DSCs.
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| 5. |
- Fan, Jiandong, et al.
(författare)
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Enhanced Photovoltaic Performance of Nanowire Dye-Sensitized Solar Cells Based on Coaxial TiO2@TiO Heterostructures with a Cobalt(II/III) Redox Electrolyte
- 2013
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 5:20, s. 9872-9877
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Tidskriftsartikel (refereegranskat)abstract
- The growth of a TiO shell at the surface of TiO2 nanowires (NWs) allowed us to improve the power conversion efficiency of NW-based dye-sensitized solar cells (DSCs) by a factor 2.5. TiO2@TiO core-shell NWs were obtained by a two-step process: First, rutile-phase TiO2 NWs were hydrothermally grown. Second, a hongquiite-phase TiO shell was electrochemically deposited at the surface of the TiO2 NWs. Bare TiO2 and heterojunction TiO2@TiO NW-based DSCs were obtained using a cobalt(II/III) redox electrolyte and LEG4 as the dye. With this electrolyte/dye combination, DSCs with outstanding V-oc values above 900 mV were systematically obtained. While TiO2@TiO NW-based DSCs had slightly lower V-oc values than bare TiO2 NW-based DSCs, they provided 3-fold higher photocurrents, overall reaching 2.5-fold higher power conversion efficiencies. The higher photocurrents were associated with the larger surface roughness and an enhanced charge-carrier separation/transfer at the NW/dye interface.
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| 6. |
- Fan, Jiandong, et al.
(författare)
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Influence of the Annealing Atmosphere on the Performance of ZnO Nanowire Dye-Sensitized Solar Cells
- 2013
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 117:32, s. 16349-16356
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Tidskriftsartikel (refereegranskat)abstract
- Postsynthesis thermal treatments are key to promote crystallinity and reduce the defect density in solution-processed nanomaterials. In particular, the annealing atmosphere strongly influences the functional properties of ZnO nanowires (NWs) and specifically their performance as photoanodes in dye-sensitized solar cells (DSCs). We prepared vertically aligned ZnO NWs by a low-cost, high-yield, and up-scalable hydrothermal method and studied the effect of the postannealing atmosphere on their optoelectronic properties and on their performance as electrodes in DSCs. When annealing ZnO NWs under argon, instead of air, significantly higher photoluminescence (PL) UV emission and relatively lower defects-related visible PL emission were obtained. At the same time, Ar-annealing rendered ZnO NWs with higher electrical conductivities, as observed from single NW measurements using conductive-atomic force microscopy. Furthermore, DSCs based on ZnO NWs annealed in argon were characterized by 50% higher photocurrents than those obtained from air-annealed ZnO. As a result 30% efficiency increases were systematically obtained when using argon as the annealing atmosphere. These results are discussed within the framework of a multiple trapping model for transport and charge transfer, taking into account differences in the defect concentration introduced during the annealing.
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| 7. |
- Zhao, Yawei, et al.
(författare)
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Fine-tuning the coordination atoms of copper redox mediators : an effective strategy for boosting the photovoltage of dye-sensitized solar cells
- 2019
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 7:20, s. 12808-12814
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Tidskriftsartikel (refereegranskat)abstract
- Natural systems have marvelously utilized copper complexes featuring sulfur-coordinating ligands, known as blue copper proteins, as efficient electron-transfer mediators in biological processes. Copper complexes with sulfur-coordinating ligands have been attempted as redox mediators in dye-sensitized solar cells (DSCs), the performance of which is not yet satisfactory and still remains less well explored. Herein, we report the application of new copper complexes bearing a tetradentate polythioether ligand, [(S-4)Cu](2+/+) (1(2+/+), S-4 = 1,4,8,11-tetrathiocyclotetradecane), as a redox mediator in DSCs in comparison with its N-4-tetradentate counterpart [(N-4)Cu](2+/+) (2(2+/+), N-4 = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). Impressively, the changes of coordination atoms from N to S positively shift the formal redox potential of the copper complexes by 600 mV, leading to a remarkably high photovoltage approaching 1.0 V. This is one of the highest photovoltage values reported thus far for DSCs based on copper redox mediators.
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