Ordered Ag/Si nanowires array: wide-range surface-enhanced Raman spectroscopy for reproducible biomolecule detection.

Surface-enhanced Raman scattering (SERS) systems utilizing the interparticle nanogaps as hot spots have demonstrated ultrasensitive single-molecule detection with excellent selectivity yet the electric fields are too confined in the small nanogaps to enable reproducible biomolecule detections. Here, guided by finite-difference-time-domain simulation, we report hexagonal-packed silver-coated silicon nanowire (Ag/SiNW) arrays as a nanogap-free SERS system with wide-range electric fields and controlled interwire separation. Significantly, the system achieves a SERS detection of long double-strand DNA of 25-50 nm in length with a relative standard deviation (RSD) of 14% for measurements of above 4000 spots over an area of 200 × 200 µm(2). The high reproducibility in the SERS detection is attributed to (1) the large interwire spacing of 150 nm that allows access and excitation of large biomolecules; and (2) 600 nm wide-range electric field generated by propagating surface plasmons along the surface of continuous Ag coating on a SiNW. Moreover, a reproducible multiplex SERS measurement is also demonstrated with RSDs of 7-16% with an enhancement factor of ~10(6). The above results show that the ordered Ag/SiNW array system may serve as an excellent SERS platform for practical chemical and biological detection.

Synthesis of In2O3-In2S3 core-shell nanorods with inverted type-I structure for photocatalytic H2 generation.

In2O3-In2S3 core-shell nanostructures were prepared via a simple hydrothermal process at low temperatures. Ultraviolet photoelectron spectroscopy (UPS) shows that the In2O3-In2S3 nanorod is an inverted type I nanostructure. The energy potential in this structure would drive both the photo-generated holes and electrons towards the shell to facilitate photocatalytic H2 generation. Such inverted type-I nanostructure is firstly used for hydrogen generation. Comparing with reported indium-based photocatalysts upon UV-Vis illumination, the core-shell In2O3-In2S3 nanostructure obtained here exhibits a good H2 evolution rate of 61.4 µmol h(-1) g(-1).

Large-scale synthesis of Cu2SnS3 and Cu(1.8)S hierarchical microspheres as efficient counter electrode materials for quantum dot sensitized solar cells.

Exploration of new catalytic semiconductors with novel structures as counter electrode materials is a promising approach to improve performances of quantum dot sensitized solar cells (QDSSCs). In this work, nearly mono-disperse tetragonal Cu(2)SnS(3) (CTS) and rhombohedral Cu(1.8)S hierarchical microspheres with nanometer-to-micrometer dimensions have been synthesized respectively via a simple solvothermal approach. These microspheres are also demonstrated as efficient counter electrode materials in solar cells using ZnO/ZnSe/CdSe nanocables as photoanode and polysulfide (S(n)(2-)/S(2-)) solution as electrolyte. While copper sulfide is regarded as one of the most effective counter electrode materials in QDSSCs, we demonstrate the CTS microspheres to show higher electrocatalytic activity for the reduction of polysulfide electrolyte than the Cu(1.8)S microspheres. This contributes to obvious enhancement of photocurrent density (J(SC)) and fill factor (FF). Power conversion efficiency (PCE) is significantly enhanced from 0.25% for the cell using a pure FTO (SnO(2):F) glass as counter electrode, to 3.65 and 4.06% for the cells using counter electrodes of FTO glasses coated respectively with Cu(1.8)S and CTS microspheres.

Facile synthesis of a large quantity of graphene by chemical vapor deposition: an advanced catalyst carrier.

A large quantity of highly conductive graphene was prepared by a novel CVD method with nickel powder as a template and PMMA as carbon source. With Pt as a model, PtNP-modified graphene showed much better electrocatalytic ability for O(2) and methanol than PtNP-reduced graphene oxide (RGO) and commercial Pt/C, showing that this graphene is a better catalyst carrier than RGO and commercial carbon.

Fabrication and structure characterization of te butterfly nanostructures.

Te nanowires and butterfly nanostructures have been fabricated by template-free electrodeposition (TFED) in aqueous solution. By high-resolution transmission electron microscopy (HRTEM) study, the favored growth directions of the nanowires and the wings of the butterfly nanostructures were determined to be along the [0001] direction of trigonal Te, and the twinning plane of the butterfly nanostructures was (11-22). The cathodoluminescence measurements carried out at different positions of the butterfly nanostructure indicated that the twin boundaries influenced the photoemission efficiency.