Enhanced photoluminescence of CdSe quantum dots by the coupling of Ag nanocube and Ag film

The coupling of local surface plasmon （LSP） of nanoparticle and surface plasmon （SP） mode produced by metal film can lead to the enhanced electromagnetic field, which has an important application in enhancing the fluorescence of quantum dots （QDs）. Herein, the Ag nanocube and Ag film are used to enhance the fluorescence of CdSe QDs. The enhancement is found to relate to the sizes of the Ag nanocube and the thickness of the Ag film. Moreover, we also present the fluorescence enhancement caused by only SP. The result shows that the coupling between metal nanoparticles and metal film can realize larger field enhancement. Numerical simulation verifies that a nanocube can localize a strong electric field around its comer. All the results indicate that the fluorescence of QDs can be efficiently improved by optimizing the parameters of Ag film and Ag cubes.

Controllable Synthesis of Ag Nanocubes via a Polyol Method

The controllable synthesis of uniform silver nanocubes with high purity is pivotal for the fundamental study of self-assembly and further research on the hollow nanostructures,gold nanocages for instance.Here,Ag nanocubes of different sizes were synthesized by an improved polyol method.With addition of HCl solution,Ag nanocubes with size about 100 nm were obtained under an air atmosphere.And Ag nanocubes with size around50 nm can be produced in a short time under Argon atmosphere with the presence of NaHS instead of HCl.Meanwhile,uniform Ag nanocubes with size larger than 100 nm were also synthesized successfully via adjusting experiment parameters.Results of transmission electron microscopy(TEM)combined with selected area electron diffraction(SAED)show that the Ag nanocubes are single crystalline with six(200)surface plane.In the UV-Vis-NIR optical absorption spectrum,the diple moment resonance absorption peak is changed in the range of 420—500nm with the increase of Ag nanocubes size.

Rational Design ofAg Nanocubes-Reduced Graphene Oxide Nanocomposites for High-performance Non-enzymatic H2O2 Sensing

Ag nanocubes-reduced graphene oxide（AgNCs-rGO） nanocomposite was successfully prepared by an in situ synthesis method, in which AgNCs were loaded onto the surface of rGO during the formation of AgNCs in an ethylene glycol solution. Characterization by X-ray diffraction, UV-Vis spectroscopy, and scanning electron microscopy indicated the successful preparation of the AgNCs-rGO nanocomposite. Most importantly, the AgNCs-rGO nanocomposite exhibited excellent electrocatalytic activity for the reduction of H2O2, leading to a high-performance non-enzymatic H2O2 sensor with a linear detection range and detection limit of approximately 0.1 mmol/L to 70 mmol/L（r=0.999） and 0.58 μmol/L, respectively. Our present work provides a new and highly efficient method for fabricating high-performance electrochemical sensors.

A novel method to prepare Au nanocage@SiO_2 nanoparticle

Gold （Au） nanocage@SiO2 nanoparticles are prepared by a novel approach. The silver （Ag） nanocube@SiO2 structure is synthetized firstly. Next, the method of etching a SiO2 shell by boiling water is adopted to change the penetration rate of AuCl4- through the SiO2 shell. AuCl4- can penetrate through silica shells of different thickness values to react with the Ag nanocube core by changing the incubation time. The surface plasma resonance （SPR） peak of synthetic Au nanocage@SiO2 can be easily tuned into the near-infrared region. Besides, CdTeS quantum dots （QDs） are successfully connected to the surface of Au nanocage@SiO2, which testifies that the incubation process does not change the property of silica.

Free-Standing Silver Nanocube/Graphene Oxide Hybrid Paper for Surface-Enhanced Raman Scattering

Surface-enhanced Raman spectroscopy （SERS） as a powerful analytical tool has gained extensive attention. Despite of many efforts in the design of SERS substrates, it remains a great challenge for creating a universal sub- strate with long-term stability and reproducible SERS signals. In this work, Ag nanocubes and graphene oxide （GO） suspension were mixed to form a stable solution and further vacuum filtrated to obtain a free-standing hybrid paper. The Ag/GO hybrid papers exhibit excellent SERS activity because of the synergistic effect of Ag nanocubes and GO sheets. GO sheets can act as both SERS enhancement substrate and framework for supporting Ag nanocubes. Moreover, GO sheets can protect Ag nanoparticles from oxidation under ambient condition for prolonged life time SERS substrate. Furthermore, we demonstrate the use of the free-standing and flexible Ag/GO hybrid paper to en- able direct, real-time and reliable detection of trace amounts of analytes in aqueous systems. This novel SERS sub- strate is expected to be applied in real-time analysis and expands the flexibility of SERS for useful applications in the materials and life science.