ABSTRACT
Mercury ions sensing is an important issue for human health and environmental safety. A novel fluorescence nanosensor was designed for rapid visual detection of ultratrace mercury ions (Hg2+) by using CH3NH3PbBr3 perovskite quantum dots (QDs) based on the surface ion-exchange mechanism. The synthesized CH3NH3PbBr3 QDs can emitt intense green fluorescence with high quantum yield of 50.28%, and can be applied for Hg2+ sensing with the detection limit of 0.124 nM (24.87 ppt) in the range of 0 nM-100 nM. Furthermore, the interfering metal ions have no any influence on the fluorescence intensity of QDs, showing the perovskite QDs possess the high selectivity and sensitivity for Hg2+ detection. The sensing mechanism of perovskite QDs for Hg2+ is has also been investigated by XPS, EDX studies, showing Pb2+ on the surface of perovskite QDs has been partially replaced by Hg2+. Spot plate test shows that the perovskite QDs can also be used for visual detection of Hg2+. Our research indicated the perovskite QDs are promising candidates for the visual fluorescence detection of environmental micropollutants.
ABSTRACT
The phosphorescent l-cysteine modified manganese-doped zinc sulfide quantum dots (l-cys-MnZnS QDs) was developed for a highly sensitive detection of permanganate anions (MnO4-). l-cys-MnZnS QDs, which were easily synthesized in aqueous media using safe and low-cost materials, can emit intense phosphorescence even though the solution was not deoxygenated. However, the phosphorescence of l-cys-Mn-ZnS QDs was strongly quenched by MnO4- ascribed to the oxidation of l-cys and the increase of surface defects on l-cys-MnZnS QDs. Under the optimal conditions, l-cys-MnZnS QDs offer high selectivity over other anions for MnO4- determination, and good linear Stern-Volmer equation was obtained for MnO4- in the range of 0.5-100µM with a detection limit down to 0.24µM. The developed method was finally applied to the detection of MnO4- in water samples, and the spike-recoveries fell in the range of 95-106%.
ABSTRACT
To reduce the cost of the catalyst for direct ethanol fuel cells and improve its catalytic activity, highly ordered Ni-Cu alloy nanowire arrays have been fabricated successfully by differential pulse current electro-deposition into the pores of a porous anodic alumina membrane (AAMs). The energy dispersion spectrum, scanning and transmission electron microscopy were utilized to characterize the composition and morphology of the Ni-Cu alloy nanowire arrays. The results reveal that the nanowires in the array are uniform, well isolated and parallel to each other. The catalytic activity of the nanowire electrode arrays for ethanol oxidation was tested and the binary alloy nanowire array possesses good catalytic activity for the electro-oxidation of ethanol. The performance of ethanol electro-oxidation was controlled by varying the Cu content in the Ni-Cu alloy and the Ni-Cu alloy nanowire electrode shows much better stability than the pure Ni one.
ABSTRACT
Sonochemical method was used to prepare ultrafine Azithromycin. The morphology and size distribution of the particles prepared were characterized by scanning electron micrograph (SEM) and Zetasizer Nanoinstrument. The chemical bonding of production was examined by Fourier transform infra-red absorption spectroscopy (FT-IR). The result shows that different diameter particles of Azithromycin were prepared, and no fundamental bonding change in the Azithromycin molecule after preparation.
