分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: We describe the synthesis of bimetallic dendritic platinum decorated gold nanorods (AuNRs) by the spatial control of Pt growth over gold nanorods using a heterogeneous seed-mediated growth method. The amounts of the Au seed and Pt-precursor were changed to achieve a tunable volume fraction of Pt coverage on the Au NRs surface. Pt nanostructures were spatially separated from each other, which was highly favorable for promising optical and catalytic properties. The dendritic-Pt decorated AuNRs with variable Au/Pt ratios were exploited to study their surface plasmonic properties and catalytic activities. Interestingly, the Pt decorated AuNRs showed strong surface plasmon resonance (SPR) peak due to noncompact dendritic Pt shell in contrast to the conventional core–shell Au@Pt nanoparticles (NPs). Moreover, the longitudinal peak of the AuNRs was finely tuned from 820 to 950 nm (NIR region) by controlling the volume fraction of the Pt decoration over the AuNRs. The catalytic activity of the dendritic-Pt decorated AuNRs on the reduction of 4-nitrophenol (4-NP) by sodium borohydride (NaBH4) as reducing agent was studied and found to be superior to the activities compared to the monometallic Au NRs. Considering practical applications, dendritic-Pt decorated AuNRs nanostructures were immobilized successfully on the hydrophilic polyvinylidene difluoride (PVDF) film as an efficient reusable catalyst.
提交时间: 2017-05-02
摘要: Development of self-healing polymers with spontaneous self-healing capability and good mechanical performance is highly desired and remains a great challenge. Here, mechanical robust and self-healable supramolecular hydrogels have been fabricated by using
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: A polymer-based visible and quantitative fluorometric assay for CO2 gas is constructed using branched polyethyleneimine (PEI) covalently modified with tetraphenylethylene (TPE). The sensing mechanism relies on the reaction of CO2 with alkylamines of PEI to induce the “solution-to-precipitation” phase transi- tion of the sensory polymer (TPE–PEI), thus resulting in strong aggregation-induced fluorescent emission of TPE–PEI. It works in a relatively environmental benign ethanol medium and avoids the use of toxic amine compounds with unpleasant odor. More importantly, this system is proved to be highly tolerant to possibly coexisting water, carbon monoxide, acid SO2 and H2 S gases as well as many common volatile organic compounds. These characteristics make the presently developed fluorescent chemosensor hold great potential for many real-world applications.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Bimetallic nanocatalysts often display enhanced physical and chemical properties compared to those of their monometallic counterparts. Herein, we introduce a simple method to fabricate an island like array of tiny Ag nanoparticles bounded on triangular Au nanoplates as the surface-enhanced Raman scattering (SERS) substrate. The surface morphology of the synthesized nanoparticles was characterized via field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). Rhodamine 6G (R6G) is used as a model analyte to evaluate the performance of the tiny Ag nanoparticle bounded triangular Au nanoplates as a SERS-active substrate and validate the SERS effect. The fabricated SERS substrate showed drastically enhanced intensity with a SERS enhancement factor as high as 107, which is enough to detect a single molecule, and excellent reproducibility (less than `5%) of the signal intensity. This is because of the island-like tiny Ag nanoparticle bounded triangular Au nanoplates and their large number of “hot spots”. This substrate could also be used for label-free immunoassays, biosensing, and nanoscale optical antennas and light sources.
提交时间: 2017-05-02
摘要: High fidelity and regularity structures of nanoscale materials has opened up new opportunities for developing miniaturized devices. A simple yet robust approach of magnetic field assisted controlled evaporative self-assembly [CESA] is developed to achieve
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Poly(vinylidene fluoride) (PVDF) membranes have been widely applied to treat wastewater, however, the removal of toxic aromatic phenolic compounds remains a technical challenge due to the serious adsorption fouling and difficult degradation. Herein, we aimed to design a superhydrophilic PVDF membrane decorated with Au nanoparticles, which enhanced the rapid degradation of p-nitrophenol (4-NP). The superhydrophilic PVDF membrane with a micro/nano structured surface was decorated with Au nanoparticles via poly(dopamine) (PDA) as a spacer. The influences of membrane affinity (e.g. Hydrophilic Membrane (HM), micro/nano structured superhydrophilic membrane (MSiM), and micro/ nano structured superhydrophobic membrane (MSoM)) on PDA deposition and the subsequent Au decoration were comprehensively investigated. The synthesized Au nanoparticles were characterized using transmission electron microscopy (TEM) and UV-vis absorption spectra. The morphology and composition was evaluated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Static catalytic experiments demonstrated that MSiM degraded over 90% of 4-NP in 5 minutes with a kinetic reaction rate constant of 47.84 10 2 min 1 and high stability over 6 cycles. A membrane catalytic reactor (MCR) was designed to realize the continuous catalytic degradation of 4-NP with a kinetic reaction rate constant of 7 10 2 min 1.