Highly fluorescent and color tunable AgInS 2 (AIS) and (AgInS 2 )x(ZnS) 1-x (AIZS) quantum dots (QDs) were prepared via a facile aqueous-phase synthesis using AgNO 3 , In(NO 3 ) 3 , Zn(OAc) 2 and Na 2 S as precursors and 3-mercaptopropionic acid (3-MPA) as ligand. Produced AIZS QDs exhibit a small diameter (ca. 2.1 nm) and a cubic structure. Ag-3-MPA and In-3-MPA complexes formed during the preparation of AIS cores were found to play a key role on the fate of the reaction and an atypical blue-shift of the PL emission was observed with the increase of the Ag/In ratio. The photoluminescence quantum yield (PL QY) of AIS QDs is modest but increased markedly after the alloying and shelling with ZnS (up to 65%). Size and composition-selective precipitations allowed to separate up to 13 fractions of AIZS QDs with exceptionally high PL QYs (up to 78%), which is the highest value reported to date for AIZS QDs prepared in aqueous phase. These high PL QYs combined to their good colloidal stability and photostability make AIZS QDs of high potential as cadmium-free fluorescent probes for various applications like bio-imaging or sensing.
SummaryCe-doped ZnO (ZnO:Ce) nanorods have been prepared through a solvothermal method and the effects of Ce-doping on the structural, optical and electronic properties of ZnO rods were studied. ZnO:Ce rods were characterized by XRD, SEM, TEM, XPS, BET, DRS and Raman spectroscopy. 5% Ce-doped ZnO rods with an average length of 130 nm and a diameter of 23 nm exhibit the highest photocatalytic activity for the degradation of the Orange II dye under solar light irradiation. The high photocatalytic activity is ascribed to the substantially enhanced light absorption in the visible region, to the high surface area of ZnO:Ce rods and to the effective electron–hole pair separation originating from Ce doping. The influence of various experimental parameters like the pH, the presence of salts and of organic compounds was investigated and no marked detrimental effect on the photocatalytic activity was observed. Finally, recyclability experiments demonstrate that ZnO:Ce rods are a stable solar-light photocatalyst.
It was found that ZnS nanoparticles showed relatively higher antioxidant activities and antibacterial with an antifungal behavior which proves that this nanomaterials can react at the interface with the life entities.
Nickel -zinc ferrite monodisperse nanoparticles are synthesized by forced hydrolysis in diethylenglycol. FC and ZFC susceptibility curves suggest that they present superparmagnetic behaviour with a blocking temperature between 63 and 15 K depending on the zinc content. The saturation magnetization of the nanocrystals at 5 K is very close to that of bulk materials, and very high compared to that of similar particles prepared by other chemical routes. High Resolution Transmission Electron Microscopy and In-field Mössbauer studies show clearly that these relatively high values are mainly due to: (i) the high crystalline quality of the particles and (ii) a cation distribution different from the classical distribution encountered in the bulk material.
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