Operando Spectroscopy Observation of Mo Clusters-Ti C T Catalyst/Support Interface's Dynamic Evolution in Hydrogen Evolution Reaction.

The interaction between catalyst and support plays an important role in electrocatalytic hydrogen evolution (HER), which may explain the improvement in performance by phase transition or structural remodeling. However, the intrinsic behavior of these catalysts (dynamic evolution of the interface under bias, structural/morphological transformation, stability) has not been clearly monitored, while the operando technology does well in capturing the dynamic changes in the reaction process in real time to determine the actual active site. In this paper, nitrogen-doped molybdenum atom-clusters on Ti C T (Mo /N-Ti C T ) is used as a model catalyst to reveal the dynamic evolution of Mo on Ti C T during the HER process.

Fabrication of a Flexible Gold Nanorod Polymer Metafilm via a Phase Transfer Method as a SERS Substrate for Detecting Food Contaminants.

Surface enhanced Raman scattering (SERS) has been widely used in detection of food safety due to the nondestructive examination property. Here, we reported a flexible SERS film based on a polymer-immobilized gold nanorod polymer metafilm. Polystyrene-polyisoprene-polystyrene (SIS), a transparent and flexible, along with having excellent elasticity, polymer, was chosen as the main support of gold nanorods.

Rapid fabrication of flexible and transparent gold nanorods/poly (methyl methacrylate) membrane substrate for SERS nanosensor application.

Flexible substrates have been proposed for daily-life applications in SERS detection due to the prominent sample collection properties such as they can be wrapped around non-planar object surface. Combining the noble metals with polymers, flexible SERS substrates could be fabricated with advantages of light weight, transparency and high SERS sensitivity. Herein, we prepare a gold nanorods (AuNRs)/poly(methyl methacrylate) (PMMA) film as flexible SERS substrate by self-assembling a uniformly AuNRs array layer on PMMA template.

Interfacial synthesis of a three-dimensional hierarchical MoS-NS@Ag-NP nanocomposite as a SERS nanosensor for ultrasensitive thiram detection.

Interfacial self-assembly of ordered nanostructures at oil-water interfaces towards the fabrication of nanofilms has attracted the interest of plenty of scientists, since its discovery in 2004. Herein, further developments have been achieved, and we report a new strategy for the synthesis of a three-dimensional (3D) hierarchical nanostructure, through an interfacial synthesis driven microemulsion process. Thus, the synthesis route has been simplified, with the rigorous experimental conditions of traditional compositing technology.

Fabrication of Reduced Graphene Oxide (RGO)/Co O Nanohybrid Particles and a RGO/Co O /Poly(vinylidene fluoride) Composite with Enhanced Wave-Absorption Properties.

Reduced graphene oxide (RGO)/Co O nanohybrid particles, composed of reduced graphite oxide and Co O particles, have been fabricated by an in situ growth method under mild wet-chemical conditions (140 °C). A series of characterization results indicate that the as-prepared Co O particles with relatively uniform sizes are embedded in RGO layers to form unique core-shell nanostructures. The RGO/Co O /poly(vinylidene fluoride) composite was found to possess excellent absorption properties.

[Preparation of Au@SiO2 core-shell nanoparticles: controlling the optical properties].

The authros developed a new approach to preparing the Au@SiO2 core-shell nanostructure. The morphology and stability of the composite were characterized by the UV-Vis absorption spectroscopy and transmission electron microscopy (TEM) methods. The stable SERS spectra were obtained from the PMBA-functionalized Au@SiO2 composite.

Three dimensional design of large-scale TiO(2) nanorods scaffold decorated by silver nanoparticles as SERS sensor for ultrasensitive malachite green detection.

We have designed a large-scale three-dimensional (3D) hybrid nanostructure as surface-enhanced Raman scattering (SERS) sensor by decorating silver nanoparticles on TiO2 nanorods scaffold (Ag/TiO2). Taking p-mercaptobenzoic acid (PMBA) as the probe molecule, the SERS signals collected by point-to-point and time mapping modes show that the relative standard deviation (RSD) in the intensity of the main Raman vibration modes (1079, 1586 cm(-1)) is less than 10%, demonstrating good spatial uniformity and time stability. This hybrid substrate also exhibits excellent SERS enhancement effect due to the formation of high-density hot spots among the AgNPs, which was proved by finite-difference time-domain (FDTD) simulations.

In situ identification of the adsorption of 4,4'-thiobisbenzenethiol on silver nanoparticles surface: a combined investigation of surface-enhanced Raman scattering and density functional theory study.

We investigated the configuration characteristic and adsorption behavior of 4,4'-thiobisbenzenethiol (TBBT) on the surface of silver nanoparticles (NPs). Under different conditions and preparation processes, several possible surface species were produced including single-end adsorption on a silicon wafer, double-end adsorption and bridge-like adsorption. Although consisting of the same molecule and nano material, different adsorption systems exhibited different spectral characteristics in the surface-enhanced Raman spectroscopy (SERS).

Chemical effects in SERS of pyrazine adsorbed on Au-Pd bimetallic nanoparticles: a theoretical investigation.

Chemical enhancement in surface-enhanced Raman scattering (SERS) of pyrazine adsorbed on Au-Pd nanoclusters is investigated by using density functional theory. Changing Pd content in the bimetallic clusters enables modulation of the direct chemical interactions between the pyrazine and the clusters. The magnitude of chemical enhancement is correlated well with the induced polarizability for the complexes with low Pd content, which fails for the complexes with high Pd content.

A DFT investigation of surface-enhanced Raman scattering of adenine and 2'-deoxyadenosine 5'-monophosphate on Ag20 nanoclusters.

We present a detailed analysis of the surface-enhanced Raman scattering (SERS) of adenine and 2'-deoxyadenosine 5'-monophosphate (dAMP) adsorbed on an Ag(20) cluster by using density functional theory. Calculated Raman spectra show that spectral features of all complexes depend greatly on adsorption sites of adenine and dAMP. The complexes consisting of adenine adsorbed on the Ag(20) cluster through N3 reproduce the measured SERS spectra in silver colloids, and thus demonstrated that adenine interacts with the silver surface via N3.

Quantitative analysis of mononucleotides by isotopic labeling surface-enhanced Raman scattering spectroscopy.

A novel surface-enhanced Raman scattering (SERS) approach for accurate quantification of mononucleotides of deoxyribonucleic acid (DNA) is described. Reproducible SERS measurement was achieved by using isotopically labeled internal standard. By measuring the SERS spectra of mononucleotides and its isotope internal standard in combination with multivariate data analysis, the method was successfully applied to quantify mononucleotides.

Controlled dispersion of silver nanoparticles into the bulk of thermosensitive polymer microspheres: tunable plasmonic coupling by temperature detected by surface enhanced Raman scattering.

By in situ reduction of Ag(+) ions pre-dispersed inside thermosensitive microspheres of poly[(N-isopropylacrylamide)-co-(methacrylic acid)] (P(NIPAM-co-MAA)), a 3D copolymer-supported network of silver nanoparticles is created and extensively characterized by surface-enhanced Raman scattering (SERS). The effective dispersion and the suitable density of the silver nanoparticles in the composite microspheres are demonstrated by the thermal-induced SERS signal and its high reproducibility during thermocycling. When the temperature of the system increases above 32 °C, spatial separation of the silver nanoparticles decreases and the numbers of Ag nanoparticles and P(NIPAM-co-MAA) microspheres under illumination spot increase as a result of the shrinkage of the P(NIPAM-co-MAA) chains, leading to the ramp of the SERS effect.

Surface-enhanced Raman spectroscopy with self-assembled cobalt nanoparticle chains: Comparison of theory and experiment.

The surface-enhanced Raman scattering (SERS) properties of 4-aminothiophenol (PATP) adsorbed on self-assembled cobalt nanoparticle chains have been investigated. Based on the density functional theory (DFT), the experimental results were in good agreement with the calculated values of the characteristic bands both for normal Raman and SERS spectra. The enhancement factor (EF) of 10(4)-10(5) indicated that high quality of surface Raman signals could be obtained, which was consistent with discrete-dipole approximation (DDA) calculation results.

First-principles characterization of the anisotropy of theoretical strength and the stress-strain relation for a TiAl intermetallic compound.

We perform first-principles computational tensile and compressive tests (FPCTT and FPCCT) to investigate the intrinsic bonding and mechanical properties of a γ-TiAl intermetallic compound (L 1(0) structure) using a first-principles total energy method. We found that the stress-strain relations and the corresponding theoretical tensile strengths exhibit strong anisotropy in the [001], [100] and [110] crystalline directions, originating from the structural anisotropy of γ-TiAl. Thus, γ-TiAl is a representative intermetallic compound that includes three totally different stress-strain modes.

[Structural and optical characterization of ZnO thin films grown by plasma-assisted molecular beam epitaxy].

High-quality ZnO thin films were grown by plasma-assisted molecular beam epitaxy (P-MBE) on Al2 O3 (0001) substrate with a low temperature ZnO buffer layer. Structural and optical characterization were studied for ZnO thin films. Only a peak at (0002) were observed in the X-ray reflectivity (XRD) spectra with the full-width at half maximum (FWHM) value 0.

A highly regular hexapod structure of lead sulfide: solution synthesis and Raman spectroscopy.

A highly regular hexapod-like structure of PbS with six symmetric arms has been synthesized by a simple and mild chemical solution route. The hexapod-like PbS structure was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). The results show that each arm is perpendicular to the other four, and opposite to the last one.

Structures and stability of N13+ and N13- clusters.

The structures and stabilities of eleven N13+ and N13- isomers have been investigated with second-order Moller-Plesset (MP2) and density functional theory (DFT) methods. Five N13+ isomers and six N13- isomers are all reasonable local minima on their potential energy hypersurfaces. The most stable N13+ cation is structure C-2 with C2v symmetry, which contains a pentazole ring and two N4 open chains.