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Articles you may be interested inStructure and ionic conductivity of ionic liquid embedded PEO-LiCF3SO3 polymer electrolyte AIP Advances 4, 087112 (2014); 10.1063/1.4892855 Ion and polymer dynamics in polymer electrolytes PPO -Li Cl O 4 . II . H 2 and Li 7 NMR stimulated-echo experimentsCorrelating the NMR self-diffusion and relaxation measurements with ionic conductivity in polymer electrolytes composed of cross-linked poly(ethylene oxide-propylene oxide) doped with LiN(SO 2 CF 3 ) 2 Solid polyethyleneoxides ͑PEO͒ are in effect ''polymer liquids'' due to their flexibility and high solubility for alkaline salts. To clarify the role of PEO in electrolyte systems, electrolytes composed of members of the ''glyme family'' ͓i.e., diglyme͑DG͒, triglyme͑TG͒, tetraglyme͑TeG͒, pentaglyme͑PG͒, and polyethyleneglycol dimethyl ethers͑PEGDM͔͒ doped with LiN(SO 2 CF 3 ) 2 were investigated. PEGDMs form a series of low molecular weight PEO-like homologues with molecular weights between 400 and 2500. Electrolytes of the glymes and PEGDMs were prepared for two salt concentrations ͑ether oxygen: lithium; O:Li͒ 20:1 and 10:1. The ionic conductivities and the self-diffusion coefficients of the solvent, anion and lithium ions in the electrolytes were measured using pulsed-field gradient spin-echo ͑PGSE͒ 1 H, 19 F, and 7 Li NMR, respectively. From the spin-lattice relaxation times (T 1 ) it was found that the segmental motions of the CH 2 CH 2 O moiety and the lithium hopping motions are correlated and that the rate of the segmental motions decreases as the molecular size of the solvent increases. The ionic conductivities calculated from the diffusion coefficients are compared with the experimental ac ionic conductivities. The diffusion and ion conduction mechanisms are discussed and the lithium ion-solvent interactions are shown to depend on the solvent size.

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Photocatalytic activity of pure TiO2 is limited to ultraviolet (UV) light due to the wide bandgap of anatase and rutile phases. The bandgap of high-pressure phases of TiO2 can theoretically coincide with visible light, but these phases are unstable at ambient pressure. In this work, the high-pressure TiO2-II (columbite) phase with large fractions of oxygen vacancies was stabilized by inducing plastic strain to anatase under 6 GPa. The material could absorb visible light as a consequence of bandgap narrowing by ∼0.7 eV. Formation of nanosized TiO2-II enhanced the hydrogen generation efficiency under visible light, and the efficiency improved after removing the oxygen vacancies by annealing.