We demonstrate that uniform dispersion of TiO(2) on graphene is critical for the photocatalytic effect of the composite. The hydrothermal method was employed to synthesize TiO(2) nanowires (NW) and then fabricate graphene-TiO(2) nanowire nanocomposite (GNW). Graphene oxide (GO) reduction to graphene and hybridization between TiO(2) NWs and graphene by forming chemical bonding was achieved in a one-step hydrothermal process. Graphene-TiO(2) nanoparticle (NP) nanocomposite (GNP) was also synthesized. Photocatalytic performance and related properties of NP, NW, GNP, and GNW were comparatively studied. It was found that by incorporation of graphene, GNP and GNW have higher performance than their counterparts. More importantly, it was found that NWs, in comparison with NPs, have more uniform dispersion on graphene with less agglomeration, resulting in more direct contact between TiO(2) and graphene, and hence further improved electron-hole pairs (EHPs) separation and transportation. The adsorbability of GNW is also found to be higher than GNP. The result reveals that the relative photocatalytic activity of GNW is much higher than GNP and pure NWs or NPs.

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Structures for interfacial water condensed in pores and channels of the fluorinated ionomer Nafion from low relative humidity atmosphere were probed through the use of Fourier transform infrared (FTIR) spectroscopy and support from classical and quantum chemical calculations. Modern FTIR spectra of H2O and the O-H stretching region for the deuterium-substituted HOD species interacting at the water-ionomer interface in Nafion exchanged by sodium cations are reported and compared to characteristics observed in the earlier studies that employed a dispersive infrared spectrometer and unspecified spectral resolution. Molecular simulations that examine the orientations of water molecules in the vicinity of ionomer were applied to understand the appearance of multiple free O-H stretching bands and the effect of HOD addition. One computational approach was based on a classical force field model, and the other employed density functional theory (DFT) to investigate atomic-scale interactions of water with regions of different hydrophobicity and charge on a perfluorosulfonate ionomer segment. The results suggest hydrogen bonding stabilizes the types of water-ionomer environments that can lead to multiple free O-H stretching vibrational features in experimental spectra. The studies shed light on the structure of H2O at interfaces inside ion conducting membrane materials and have potential for application in elucidating structure at different types of water interfaces.

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In this research, centrifugally spun ultrafine composite starch/polyvinyl alcohol (ST/PVA) fibers with high water stability were prepared by cross-linking with a mixture of glutaraldehyde and formic acid in the form of vapor phase. The effect of cross-linking temperature combined with time on the water stability, crystal structure, and thermal properties of fibers was investigated to obtain the optimum parameters. On this basis, we further prepared Ag-loaded ST/PVA fibers with different contents of nano silver. The structure and properties of Ag-loaded fibers, which cross-linked under the optimum parameters, were analyzed. As a result, the Ag-loaded fibers exhibited excellent water stability and mechanical properties and possessed inhibition zone diameters of 3 and 2 mm to Escherichia coli and Staphylococcus. aureus, respectively. The antibacterial property of the Ag-loaded ST/ PVA fibers provided a new route for developing less costly antibacterial fiber materials in the future.

We report here a new global and full dimensional potential energy surface (PES) for the F + CH4 reaction. This PES was constructed by using neural networks (NN) fitting to about 99 000 ab initio energies computed at the UCCSD(T)-F12a/aug-cc-pVTZ level of theory, and the correction terms considering the influence of a larger basis set as well as spin-orbit couplings were further implemented with a hierarchial scheme. This PES, covering both the abstraction and substitution channels, has an overall fitting error of 8.24 meV in total, and 4.87 meV for energies within 2.5 eV using a segmented NN fitting method, and is more accurate than the previous PESs.

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