- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
New Insights Into the Growth Mechanism of Ultrathin Au Nanowires from Combined In-Situ EXAFS and SAXS Studies
摘要： The synthesis at room temperature of Au nanowires (NWs) in hexane solution of HAuCl4.3H2O, oleylamine and triisopropylsilane, was “in-situ” monitored by means of X-ray Absorption Fine Structure Spectroscopies and Small Angle X-Ray Scattering to determine, under identical synthesis conditions, both the changes of the oxidation state of gold atoms and the evolution of the size and shape of the objects involved in the formation of Au NWs. We propose a multi-stage process for the formation of the NWs: first, Au(III) atoms form a planar-square geometry complex that is continuously reduced to give Au(I) disc-like structures with diameters bigger than that of the final NWs. In a second stage, characteristic length/thickness ratio of these disc-like objects increases to form cylinders, presumably by aurophilic interactions between Au(I) centers and stacking of the discs. When most of the Au atoms have been reduced to Au(I), the reduction to Au(0) begins (third stage) and the NWs grow forming an hexagonal arrangement, separated by a bilayer of oleylamine molecules (fourth stage). Finally, a slow reduction leads the reaction to the final product, formed by bundles of long, ultrathin Au NWs.
关键词： triisopropylsilane,in-situ EXAFS,growth mechanism,SAXS,Au nanowires,oleylamine
更新于2025-09-23 15:21:21
-
Top-down Fabrication of Colloidal Plasmonic MoO <sub/>3-x</sub> Nanocrystals via Solution Chemistry Hydrogenation
摘要： A high-efficiency top-down approach was used to fabricate orthorhombic MoO3-x nanocrystals through the synergic effect of oleic acid (OA) and oleylamine (OAm), in which OA providing H+ ions and OAm contributing free electrons. This investigation might provide new guidance for manipulating the optical properties of metal oxide semiconductors.
关键词： top-down fabrication,solution chemistry hydrogenation,oleic acid,oleylamine,colloidal plasmonic MoO3-x nanocrystals
更新于2025-09-23 15:19:57
-
Ultralong CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> nanowires synthesized by a ligand-assisted reprecipitation strategy for high-performance photodetectors
摘要： Organic-inorganic hybrid perovskite nanowires with well-defined structures have attracted considerable attention for optoelectronic applications. Perovskite nanowires integrated into practical optoelectronic devices are often hindered by the poor crystalline quality. Herein, a ligand-assisted reprecipitation strategy (LARP) is employed to prepare ultralong and freestanding CH3NH3PbI3 nanowires in large-scale. Oleylamine is adopted as an inhibitor, which can create a passivation layer on the surface of CH3NH3PbI3, to slow down the crystallization rate of CH3NH3PbI3 nanowire. With the low crystallization rate, several millimeters long and high-quality CH3NH3PbI3 nanowires with smooth surfaces can be synthesized in a large scale. Photodetectors fabricated on oleylamine assistant synthesized CH3NH3PbI3 nanowires exhibit high detectivity, which is five times higher than that of none oleylamine assistant synthesized CH3NH3PbI3 nanowires photoanode.
关键词： Organic-inorganic hybrid perovskite,photodetectors,nanowires,ligand-assisted reprecipitation strategy,optoelectronic applications,oleylamine
更新于2025-09-19 17:13:59
-
Magneto-Plasmonic Co@Pt@Au Nanocrystals for Biosensing and Therapeutics
摘要： Multifunctional nanoparticles (NPs) exhibiting high magnetic property and plasmonic resonance, are expected to be advanced nanomaterials which enable therapy, detection and diagnosis simultaneously for medical applications. To achieve the practical performance of the multifunctional NPs, the precise design and synthesis both are required. In this work, considering the chemical stability and controllability, Co-Pt@Au core-shell NPs, which exhibit high magnetic property and plasmonic resonance were theoretically designed based on calculation and then experimentally synthesized using alcohol reduction method. Co-Pt NPs were uniformly synthesized using a technique which enables reduction control of Pt through the formation of Pt-oleylamine complex. Moreover, depending on Co/Pt ratio, distribution of Co and Pt in a nanoparticle were precisely controlled, and as a result, Co-Pt alloy and Co@Pt core-shell NPs were individually prepared. In particular, Co@Pt NPs exhibit a high magnetic property and are suitable for Au coating due to a small lattice mismatch. In fact, Au coating onto Co@Pt NPs was successfully performed via inhomogeneous nucleation, which results in Co@Pt@Au NPs exhibiting plasmonic response of Au with high magnetic property and being dispersed in water by ligand-exchange for in-vivo use. The developed synthetic method enables designed synthesis of complicated multicomponent nanoparticles through tunable reduction reaction and provides highly potential NPs for transport and sensing applications.
关键词： Biomedical nanomaterials,Pt-Oleylamine complex,Magnetic and plasmonic properties,Magnetic transport,Alcohol reduction method,Sensing,Co@Pt@Au colloidal nanoparticles,Ligand exchange
更新于2025-09-11 14:15:04
-
Transformation of the Anion Sublattice in the Cation-Exchange Synthesis of Au <sub/>2</sub> S from Cu <sub/>2-x</sub> S Nanocrystals
摘要： Cation exchange is a versatile post-synthetic technique that has been exploited in the synthesis of metastable nanocrystals through preservation of the anion sublattice. Here we report on the mechanistic details of the synthesis of metastable Au2S via cation exchange with Cu2-xS nanocrystals. This conversion requires a transformation of the anion sublattice, from hcp in Cu2-xS to bcc Au2S accompanied by an expansion of the unit cell. The ligand environment plays a key role in the driving force of the reaction as the presence of oleylamine allows the conversion to proceed at room temperature while the addition of trioctylphosphine hinders the reaction. By employing transmission electron microscopy (TEM) on faceted nanocrystals and partial cation exchange of nanocrystals, it was demonstrated that the reaction proceeds in a highly directional manner through the pyramidal facets. Since cation exchange produces high quality nanocrystals as seen through XRD and TEM, UV-Vis and Raman spectroscopy were used to characterize the optoelectronic properties of the metastable Au2S nanocrsytals. A Tauc plot analysis revealed a band gap of 2.6 eV, while two intrinsic Raman modes were identified at 265 cm-1 and 329 cm-1. Density functional theory (DFT) calculations of structures, energy bands, optical spectra, and phonon spectra were performed and combined with the experimental data to provide additional insights into the characterization of Au2S nanocrystals.
关键词： XRD,Raman spectroscopy,UV-Vis,trioctylphosphine,nanocrystals,TEM,Cation exchange,DFT,Cu2-xS,anion sublattice transformation,Au2S,oleylamine
更新于2025-09-09 09:28:46