Anion type-dependent confinement effect on glass transitions of solutions of LiTFSI and LiFSI

We present findings on the effect of nanometer-sized silica-based pores on the glass transition of aqueous solutions of lithium bis(trifluoromethane)sulfonimide(LiTFSI)and lithium difluorosulfimide(LiFSI),respectively.Our experimental results demonstrate a clear dependence of the confinement effect on the anion type,particularly for water-rich solutions,in which the precipitation of crystalized ice under cooling process induces the formation of freeze-concentrated phase confined between pore wall and core ice.As this liquid layer becomes thinner,the freeze-concentrated phase experiences glass transition at increasingly higher temperatures in solutions of LiTFSI.However,differently,for solutions of LiFSI and LiCl,this secondary confinement has a negligible effect on the glass transition of solutions confined wherein.These different behaviors emphasize the obvious difference in the dynamic properties’response of LiTFSI and LiFSI solutions to spatial confinement and particularly to the presence of the hydrophilic pore wall.

Effects of water on the structure and transport properties of room temperature ionic liquids and concentrated electrolyte solutions

Transport properties and the associated structural heterogeneity of room temperature aqueous ionic liquids and especially of super-concentrated electrolyte aqueous solutions have received increasing attention,due to their potential application in ionic battery.This paper briefly reviews the results reported mainly since 2010 about the liquid-liquid separation,aggregation of polar and apolar domains in neat RTILs,and solvent clusters and 3D networks chiefly constructed by anions in super-concentrated electrolyte solutions.At the same time,the dominating effect of desolvation process of metal ions at electrode/electrolyte interface upon the transport of metal ions is stressed.This paper also presents the current understanding of how water affects the anion-cation interaction,structural heterogeneities,the structure of primary coordination sheath of metal ions and consequently their transport properties in free water-poor electrolytes.

UV illumination enhanced desorption of oxygen molecules from monolayer MoS2 surface

The oxygen adsorption can drastically alter the electronic properties of the two-dimensional(2D)materials,which is usually dificult to be removed.In this work,we report the ultraviolet(UV)ilumination induced desorption of the O2 molecules from the monolayer MoS2 surface by using the atmosphere dependent transport measurement,Kelvin probe microscopy,photoluminescence spectroscopy and X-ray photoelectron spectroscopy.Obvious increasing of the conductivity,rising of the Fermi level,and red shift of the photoluminescence peaks of the MoS2 were observed after the UV ilumination in vacuum,indicating the elimination of the depletion effect from the oxygen adsorption.Such parameter changes can be reversibly recovered by the subsequent O2 exposure.Furthermore,obvious decreasing of the oxygen concentration after the UV ilumination was also observed by X-ray photoelectron spectroscopy.Thus the UV induced O2 photodesorption effect is evidenced.The photo-excited charge transfer mechanism is proposed to account for the photodesorption effect.These results provide a nondestructive way to clean the MoS2 surface and manipulate the performance of the MoS2 based devices.

Gd_(2)O_(3) nanoparticles modified g-C_(3)N_(4) with enhanced photocatalysis activity for degradation of organic pollutants

Gd_(2) O_(3) nanoparticles modified g-C_(3) N_(4) photocatalytic composites were synthesized by a simple one-step hydrothermal method.The structure,morphology,optical properties of the prepared photocatalyst were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),field emission transmission electron microscopy(FETEM) and X-ray photoelectron spectroscopy(XPS).The result demonstrates that gadolinium is mainly dispersed on the surface of g-C_(3) N_(4) in the form of Gd_(2) O_(3),and does not destroy the lattice structure of g-C_(3) N_(4).Besides,the gadolinium can cause the red shift of the absorption edge of light,narrow the band gap,and increase the separation efficiency of the photogenerated electron and hole of g-C_(3) N_(4).Especially,the specific surface area of g-C_(3) N_(4) can be significantly increased.Furthermore,g-C_(3) N_(4)/Gd-0.05 displays the highest photodegradation performance when it is used for degradation of methyl orange(MO),methylene blue(MB) and Rhodamine B(RhB).The photodegradation rate of g-C_(3) N_(4)/Gd-0.05 composites is 72.4% for MO,95.5% for RhB,100% for MB after120 min under visible light(λ> 420 nm) irradiation.Narrow band gap promotes the separation of photogenerated electron and hole,which enhances the photocatalytic activity of g-C_(3) N_(4).It is noted that g-C_(3) N_(4)/Gd-0.05 exhibits excellent photocatalytic stability by the photocurrent and the cyclic photodegradation of MO.