Inorganic nanowires with ultrathin diameters below the magic size (i.e., less than 2 nm) and even one unit cell size, have attracted much research attention in the past few years owing to their unique chemical and physical properties. [1][2][3][4][5][6][7][8][9] As an important semiconductor material, tungsten oxide (WO 3Àx ) nanowires and nanorods have attracted considerable attention because of their wide applications in gas sensors, electrochromic windows, optical devices, and photocatalysts. [10][11][12][13] In particular, monoclinic W 18 O 49 is of great interest owing to its unusual defect structure and promising properties in the nanometer regime. [14,15] Early on, Park and co-workers reported the synthesis of W 18 O 49 nanorods with a diameter of 4 nm by decomposing [W(CO) 6 ] in Me 3 NO 2 ·2 H 2 O and oleylamine.[16] Subsequently, Niederberger and co-workers synthesized hybrid W 18 O 49 / organic nanowires with a very thin diameter of 1.3 nm by a bioligand-assisted method.[17] Recently, Tremel and coworkers prepared W 18 O 49 nanorods with a diameter of 2 nm by decomposing tungsten ethoxide in a mixture of oleic acid and trioctyl amine.[18] Although good control over nanocrystal dimensions can be realized in these methods, removal of the surfactants or organic residues from the nanowire surface requires multiple washing steps. For fundamental investigations on the ultrathin oxide nanowire itself, as well as for technological applications (such as sensing and catalysis), the presence of residues on the nanowire surface from the synthesis may be a significant drawback.Herein, we report the preparation of ultrathin W 18 O 49 nanowires that are efficient in the photochemical reduction of carbon dioxide by visible light. The ultrathin W 18 O 49 nanowires were prepared by a very simple one-pot solution-phase method (see the experimental section in the Supporting Information). In a typical procedure, WCl 6 was dissolved in ethanol, and the clear yellow solution was transferred to a teflon-lined stainless-steel autoclave and heated at 180 8C for 24 h. A blue flocculent precipitate was collected, washed, dried in air, and obtained in a yield of approximately 100 %. The product is insoluble in water and in acid (HCl, pH 0), and has a high specific surface area.W 18 O 49 is a monoclinic structure type (P2 m) with lattice parameters of a = 18.318, b = 3.782, and c = 14.028 . Monoclinic W 18 O 49 has a distorted ReO 3 structure in which cornersharing distorted and tilt WO 6 octahedra are connected in the a-, b-, and c-direction, thereby forming a three-dimensional structure (inset in Figure 1 a). The X-ray diffraction (XRD) pattern of our sample demonstrates that the sample consists of monoclinic-phase W 18 O 49 (Figure 1 a). The narrow (010) and (020) peaks strongly suggest that the possible crystal growth direction of the sample is [010], since the close-packed planes of the monoclinic W 18 O 49 crystal are {010}, which will be further demonstrated by the direct observation of the highresolution transmission electr...

Metal/semiconductor hybrid materials of various sizes and morphologies have many applications in areas such as catalysis and sensing. Various organic agents are necessary to stabilize metal nanoparticles during synthesis, which leads to a layer of organic compounds present at the interfaces between the metal particles and the semiconductor supports. Generally, high-temperature oxidative treatment is used to remove the organics, which can extensively change the size and morphology of the particles, in turn altering their activity. Here we report a facile method for direct growth of noble-metal particles on WO(3) through an in situ redox reaction between weakly reductive WO(2.72) and oxidative metal salts in aqueous solution. This synthetic strategy has the advantages that it takes place in one step and requires no foreign reducing agents, stabilizing agents, or pretreatment of the precursors, making it a practical method for the controlled synthesis of metal/semiconductor hybrid nanomaterials. This synthetic method may open up a new way to develop metal-nanoparticle-loaded semiconductor composites.

Compared with noble metals, semiconductors with surface plasmon resonance effect are another type of SERS substrate materials. The main obstacles so far are that the semiconducting materials are often unstable and easy to be further oxidized or decomposed by laser irradiating or contacting with corrosive substances. Here, we report that metallic MoO2 can be used as a SERS substrate to detect trace amounts of highly risk chemicals including bisphenol A (BPA), dichloropheno (DCP), pentachlorophenol (PCP) and so on. The minimum detectable concentration was 10−7 M and the maximum enhancement factor is up to 3.75 × 106. To the best of our knowledge, it may be the best among the metal oxides and even reaches or approaches to Au/Ag. The MoO2 shows an unexpected high oxidation resistance, which can even withstand 300 °C in air without further oxidation. The MoO2 material also can resist long etching of strong acid and alkali.

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Unsaturated fatty acids (FAs) serve as nutrients, energy sources, and signaling molecules for organisms, which are the major components for a large variety of lipids. However, structural characterization and quantitation of unsaturated FAs by mass spectrometry remain an analytical challenge. Here, we report the coupling of epoxidation reaction of the C═C in unsaturated FAs and tandem mass spectrometry (MS) for rapid and accurate identification and quantitation of C═C isomers of FAs in a shotgun lipidomics approach. Epoxidation of the C═C leads to the production of an epoxide which, upon collision induced dissociation (CID), produces abundant diagnostic ions indicative of the C═C location. The total intensity of the same set of diagnostic ions for one specific FA C═C isomer was also used for its relative and absolute quantitation. The simple experimental setup, rapid reaction kinetics (<2 min), high reaction yield (>90% for monounsaturated FAs), and easy-to-interpret tandem MS spectra enable a promising methodology particularly for the analysis of unsaturated FAs in complex biological samples such as human plasma and animal tissues.