Aprotic lithium-oxygen batteries possess ultrahigh energy density but suffer from the sluggish decomposition of discharge product,quick depletion of Li anode and cleavage of electrolyte,in close association with oxygen reduction reaction at the cathode.Herein,highly dispersed silver nanoparticles are used to enhance the lithium-oxygen battery with 1.0 M lithium perchlorate in dimethyl sulfoxide.It is observed that film-like amorphous lithium peroxide is formed through surface pathway instead of bulk crystals,due to the incorporation of silver nanoparticles dispersed in the electrolyte,which subsequently accelerates the decomposition of the discharge product by offering more active sites and improved conductivity.The released silver nanoparticles after battery charging can be re-used in the following cycles.Experiments and theoretical calculation further indicate that the suspended silver nanoparticles can adsorb the soluble oxygen reduction intermediates,which are responsible for the alleviation of oxidative cleavage of electrolyte and corrosion of lithium anode.The lifespan of lithium oxygen batteries is therefore significantly extended from 55 to 390 cycles,and the rate performance and full-discharge capacity are also largely enhanced.The battery failure is attributed to the coalescence and growth of silver nanoparticles in the electrolyte,and further improvement on colloid stability is underway.
Zhihong LuoFujie LiChengliang HuLiankun YinDegui LiChenhao JiXiangqun ZhugeKui ZhangKun Luo
Amphiphilic Janus gold nanoparticles （GNPs） are prospected to encapsulate drug molecules in cancer therapy and to serve as heterogeneous catalysts at oil/water interfaces, where Janus GNPs with differ- ent sizes are required. In this work, multiple-sized precursor GNPs were synthesized by seeded growth method protected with tris（hydroxymethyl）phosphine oxide （THPO） ligand molecule, and a ligand ex- change reaction with triphenylphosphine （PPh3） at the toluene/water interface was employed to prepare amphiphilic Janus GNPs. UV-vis and transmission electron microscopy （TEM） analyses indicate that the as-prepared GNPs are nanocrystals with average diameters of 2.3 nm, 9.5 nm, 16.1 nm and 18.8 nm, re- spectively. Contact angle, Raman and X-ray photonic spectroscopy （XPS） analyses reveal that the self- assembled GNP films exhibit hydrophilic on one side and hydrophobic on another, owing to the adsorption of hydrophilic ligands （THPO and THP） and a similar amount of hydrophobic ligands （PPh3 and PPh30）. Angle-resolved XPS analysis further demonstrates that the individual GNPs actually possess hydro- philic and hydmphobic compartments on the surface, which regularly packed by supramolecular interactions at toluene/water interface to form the self-assembled GNP films.
Kun LuoYongdong XiangHaiming WangLi XiangZhihong Luo
A facile approach to prepare a thin film vapor sensor is demonstrated through droplet interracial reaction on an IDA microelectrode. Scanning electron microscopy, atomic force microscopy and transmission electron microscopy analyses show that the film of the vapor sensor is composed of self-assembled gold nanocrystals in an average diameter of about 4.3 nm. The as-prepared sensor was examined by potential step method and impedance measurement, which exhibited significant △R/Ri responses and excellent cycle performance to the volatile organic compound （VOC） vapors of acetone, methanol, styrene, benzene, toluene and ethanol. The selectivity to the VOCs with benzene ring or organic solvents suggests that the sensor is probably in line with the swelling and dielectric sensing mechanisms.
Kun LuoTao HuangYujia LuoHaiming WangChao SangXiaogang Li
