No abstract

No abstract

Juncus is a perennial herb aquatic plant found worldwide, with high reproductive ability in warm regions. It has three-dimensional hierarchical porous triangular networks structures composited of tubular fibers. Here, juncus derived nitrogen-doped porous carbon (NDPC) was prepared by mixing juncus and ZnCl 2 through one-step pyrolysis and activation which is a low-cost, simple, and environmentally friendly method. The NDPC had hierarchical porous structures and a high specific surface area and was applied for supercapacitor and oxygen reduction reaction (ORR). The resulted NDPC-3-800 was prepared by mixing juncus with ZnCl 2 at a mass ratio of 1:3 and then carbonized at 800 • C, it was used as electrode material of a supercapacitor. The supercapacitor exhibited excellent specific capacitance of 290.5 F g −1 and 175.0 F g −1 in alkaline electrolyte at the current densities of 0.5 A g −1 and 50 A g −1 , respectively. The supercapacitor showed good cycle stability, and the capacitance was maintained at 94.5% after 10,000 cycles. The NDPC-5-800 was prepared by mixing juncus with ZnCl 2 at a mass ratio of 1:5 and then carbonized at 800 • C. It exhibited outstanding ORR catalytic activity and stability attributing to their high specific surface area and abundant actives sites. The juncus can derive various materials for application in different fields.

No abstract

In this paper, a colorimetric assay for multiplexed analysis of mercury and silver ions was demonstrated by using a rationally designed unimolecular multifunctional DNA probe (UMDP) as sensing element, and unmodified gold nanoparticles (AuNPs) as color-reporting probes. The UMDP had a random coil structure that changed into two different hairpin-like structures with a T-Hg 2+ -T or C-Ag + -C basepairing built-in the stem upon binding Hg 2+ or Ag + ions, respectively. As a result, the conformation changes facilitated the salt-induced AuNPs aggregation, leading red-to-blue color change with a red shift of the plasmon band in the UV-visible absorption spectrum. Thus, the change in absorption intensity allowed the multiplexed detection of Hg 2+ and Ag + ions. The sensing system could detect as low as 2.5 Â 10 À7 M Hg 2+ ions and 5 Â 10 À7 M Ag + ions. Both the color and absorption changes of the system were selective for Hg 2+ and Ag + ions, which met the selective requirements for biomedical and environmental application. Moreover, the two target ions were simply distinguished by using EDTA, Hg 2+ ions could not cause AuNPs aggregation while Ag + ions still could in the presence of EDTA. Then, the colorimetric response of the two target ions in spiked lake water and tap water were tested, respectively. We expect this simple and cost-effective method to have wide-ranging applications for monitoring water quality in the developing region.