| 1. |
- Fan, Qunping, 1989, et al.
(författare)
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A Non-Conjugated Polymer Acceptor for Efficient and Thermally Stable All-Polymer Solar Cells
- 2020
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Ingår i: Angewandte Chemie - International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 59:45, s. 19835-19840
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Tidskriftsartikel (refereegranskat)abstract
- A non-conjugated polymer acceptor PF1-TS4 was firstly synthesized by embedding a thioalkyl segment in the mainchain, which shows excellent photophysical properties on par with a fully conjugated polymer, with a low optical band gap of 1.58 eV and a high absorption coefficient >105 cm−1, a high LUMO level of −3.89 eV, and suitable crystallinity. Matched with the polymer donor PM6, the PF1-TS4-based all-PSC achieved a power conversion efficiency (PCE) of 8.63 %, which is ≈45 % higher than that of a device based on the small molecule acceptor counterpart IDIC16. Moreover, the PF1-TS4-based all-PSC has good thermal stability with ≈70 % of its initial PCE retained after being stored at 85 °C for 180 h, while the IDIC16-based device only retained ≈50 % of its initial PCE when stored at 85 °C for only 18 h. Our work provides a new strategy to develop efficient polymer acceptor materials by linkage of conjugated units with non-conjugated thioalkyl segments.
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| 2. |
- Gschneidtner, Tina, 1985, et al.
(författare)
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Constructing a library of metal and metal-oxide nanoparticle heterodimers through colloidal assembly
- 2020
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 12:20, s. 11297-11305
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticle dimers composed of different metals or metal oxides, as well as different shapes and sizes, are of wide interest for applications ranging from nanoplasmonic sensing to nanooptics to biomedical engineering. Shaped nanoparticles, like triangles and nanorods, can be particularly useful in applications due to the strong localized plasmonic hot-spot that forms at the tips or corners. By placing catalytic, but traditionally weakly- or non-plasmonic nanoparticles, such as metal oxides and metals like palladium, in these hot-spots, an enhanced function for sensing, photocatalysis or optical use is predicted. Here, we present an electrostatic colloidal assembly strategy for nanoparticles, incorporating different sizes, shapes and metal or metal oxide compositions into heterodimers with smaller gaps than are achievable using nanofabrication techniques. This versatile method is demonstrated on 14 combinations, including a variety of shaped gold nanoparticles as well as palladium, iron oxide, and titanium oxide nanoparticles. These colloidal nanoparticles are stabilized with traditional surfactants, such as citrate, CTAB, PVP and oleic acid/oleylamines, indicating the wide applicability of our approach. Heterodimers of gold and palladium are further analyzed using cathodoluminescence to demonstrate the tunability of these "plasmonic molecules". Since systematically altering the absorption and emission of the plasmonic nanoparticles dimers is crucial to extending their functionality, and small gap sizes produce the strongest hot-spots, this method indicates that the electrostatic approach to heterodimer assembly can be useful in creating new nanoparticle dimers for many applications.
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| 3. |
- Lerch, Sarah, 1990, et al.
(författare)
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Robust Colloidal Synthesis of Palladium-Gold Alloy Nanoparticles for Hydrogen Sensing
- 2021
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 13:38, s. 45758-45767
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Tidskriftsartikel (refereegranskat)abstract
- Metal nanoparticles are currently used in a variety of applications, ranging from life sciences to nanoelectronic devices to gas sensors. In particular, the use of palladium nanoparticles is gaining increasing attention due to their ability to catalyze the rapid dissociation of hydrogen, which leads to an excellent response in hydrogen-sensing applications. However, current palladium-nanoparticle-based sensors are hindered by the presence of hysteresis upon hydride formation and decomposition, as this hysteresis limits sensor accuracy. Here, we present a robust colloidal synthesis for palladium-gold alloy nanoparticles and demonstrate their hysteresis-free response when used for hydrogen detection. The obtained colloidal particles, synthesized in an aqueous, room-temperature environment, can be tailored to a variety of applications through changing the size, ratio of metals, and surface stabilization. In particular, the variation of the viscosity of the mixture during synthesis resulted in a highly tunable size distribution and contributed to a significant improvement in size dispersity compared to the state-of-the-art methods.
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| 4. |
- Pekkari, Anna, 1989, et al.
(författare)
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Synthesis of highly monodisperse Pd nanoparticles using a binary surfactant combination and sodium oleate as a reductant
- 2021
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 3:9, s. 2481-2487
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Tidskriftsartikel (refereegranskat)abstract
- This study presents the synthesis of monodisperse Pd nanoparticles (NPs) stabilized by sodium oleate (NaOL) and hexadecyltrimethylammonium chloride (CTAC). The synthesis was conducted without traditional reductants and Pd-precursors are reduced by NaOL. It was confirmed that the alkyl double bond in NaOL is not the only explanation for the reduction of Pd-precursors since Pd NPs could be synthesized with CTAC and the saturated fatty acid sodium stearate (NaST). A quantitative evaluation of the reduction kinetics using UV-Vis spectroscopy shows that Pd NPs synthesized with both stabilizer combinations follow pseudo first-order reaction kinetics, where NaOL provides a faster and more effective reduction of Pd-precursors. The colloidal stabilization of the NP surface by CTAC and NaOL is confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analysis.
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| 5. |
- Wen, Xin, 1991
(författare)
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Shape Control Synthesis and Microstructure Studies of Metal Nanoparticles
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metal nanoparticles have been extensively studied in recent years due to their unique chemical, biological and physical properties. Gold (Au) and palladium (Pd) nanoparticles are two of the most popular materials because Au nanoparticles have a strong localized surface plasmon resonance effect and Pd nanoparticles have high hydrogen adsorption and chemical catalytic capacities. In the colloidal-chemical synthesis of gold (Au) and palladium (Pd) nanoparticles, capping agents are widely used to control the shape and size of nanoparticles. Capping agents are usually surfactants, polymers, organic ligands and dendrimers. In this work, an anionic surfactant, sodium oleate (NaOL) was mixed with common capping agents such as hexadecyltrimethylammonium bromide (CTAB), hexadecyltrimethylammonium chloride (CTAC) and polyvinylpyrrolidone (PVP) in order to tune the shapes of nanoparticles. Three mixtures of capping agent: CTAB-NaOL, CTAC-NaOL, and PVP-NaOL were applied to the synthesis of Pd nanoparticles, resulting in the formation of Pd nanodendrites under proper circumstances including temperature, pH value and ratio between the capping agents. The large surface area makes Pd nanodendrites advantageous in catalytic applications. However, the application of CTAB-NaOL mixture in the growth of Au nanorods plays a remarkably different role. It increased the rod-shape yield and narrowed the aspect ratio of Au nanorods. A growth-induced strain was discovered in the Au nanorods, leading to slight bending in a large percentage (≈ 47%) of the Au nanorods. A variety of techniques were used to investigate the microstructure and properties of Au and Pd nanoparticles. Transmission electron microscopy including selected area electron diffraction and Kikuchi pattern methods, energy dispersive X-ray spectroscopy, and scanning transmission electron microscopy were employed to study microstructure and elemental composition. Ultraviolet-visible spectroscopy, dynamic light scattering and conductivity measurements were used to characterize the growth kinetics of metal nanoparticles. Through these techniques, the effects of the capping agent ratio, pH value and precursor types on the growth of Pd nanodendrites were investigated. Additionally, the growth-induced strain in Au nanorods was studied as well. Investigations of the shapes and microstructure of metal nanoparticles have the potential to expand their applications in the fields of surface plasmonic sensing and catalysis.
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| 6. |
- Wen, Xin, 1991, et al.
(författare)
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Synthesis of Palladium Nanodendrites Using a Mixture of Cationic and Anionic Surfactants
- 2020
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 36:7, s. 1745-1753
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Tidskriftsartikel (refereegranskat)abstract
- Surfactants are used widely to control the synthesis of shaped noble-metal nanoparticles. In this work, a mixture of hexadecyltrimethylammonium bromide (CTAB), a cationic surfactant; sodium oleate (NaOL), an anionic surfactant; palladium chloride; and a reducing agent were used in the seed-mediated synthesis of palladium nanoparticles. By controlling the surfactant mixture ratio, we initially discovered that palladium nanodendrites with narrow size distribution were formed instead of the traditional nanocubes, synthesized with only CTAB. In order to investigate the optimal ratio to produce Pd nanodendrites with a high yield and narrow size distribution, samples synthesized with multiple molar ratios of the two surfactants were prepared and studied by transmission electron microscopy, dynamic light scattering, conductance, and ultraviolet-visible spectroscopy. We propose that the addition of NaOL alters the arrangement of surfactants on the Pd seed surface, leading to a new pattern of growth and aggregation. By studying the nanodendrite growth over time, we identified the reduction period of Pd2+ ions and the formation period of the nanodendrites. Our further experiments, including the replacement of CTAB with hexadecyltrimethylammonium chloride (CTAC) and the replacement of NaOL with sodium stearate, showed that CTA+ ions in CTAB and OL- ions in NaOL play the main roles in the formation of nanodendrites. The formation of palladium nanodendrites was robust and achieved with a range of temperatures, pH and mixing speeds.
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| 7. |
- Wen, Xin, 1991, et al.
(författare)
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The Effect of the Pd Precursors on the Shape of Hollow Ag-Pd Alloy Nanoparticles Using Ag Nanocubes as Seeds
- 2023
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Ingår i: Langmuir. - 1520-5827 .- 0743-7463. ; 39:32, s. 11268-11273
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Tidskriftsartikel (refereegranskat)abstract
- Hollow Ag-Pd nanoparticles have potentially highcatalyticperformance owing to their larger surface area compared to their correspondingsolid nanoparticles. We successfully fabricated hollow Ag-Pdalloy nanodendrites and nanoboxes by using different Pd precursors(H2PdCl4 and Pd(acac)(2)) to achievelarge surface area nanoboxes. Interestingly, the use of a H2PdCl4 precursor led to the formation of hollow nanodendritestructures, whereas the slower reduction of Pd(acac)(2) ledto the formation of hollow nanoboxes. The microstructure and chemicalcomposition of Ag-Pd nanoparticles and properties of theirgrowth solutions were investigated by transmission electron microscopy,energy-dispersive X-ray spectroscopy, and ultraviolet-visiblespectroscopy.
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