Facile Fabrication of Hollow Silver-Gold Alloy Nanostructures Directly on Filter Paper for Enhanced Catalytic and Antibacterial Applications
Abstract
Hollow noble metal alloy nanostructures have recently drawn significant attention due to their remarkable potential across various applications. Although typically synthesized in solution, many applications require their deposition onto substrates. Herein, we present the novel synthesis of hollow silver-gold (Au-Ag) alloy nanostructures directly on the filter paper. The synthesis involved two steps: first, Ag nanostructures were grown on filter paper via ascorbic acid reduction of Ag ions, forming AgNS-S. These nanostructures were subsequently etched with HAuCl4 using galvanic replacement to produce HANS-S. Owing to the enhanced surface area and the presence of a high concentration of atoms in the low coordination state, the HANS-S showed excellent catalytic and antibacterial properties. In particular, the rate constant for reducing 4-nitrophenol to 4-aminophenol and degrading methyl orange increased by ~3.5x and ~3.4x, respectively, with HANS-S compared to AgNS-S. Similarly, the filter paper having hollow Au-Ag alloy nanostructures showed markedly superior antibacterial activity. While AgNS-S did not show any zone of inhibition (ZOI) outside the substrate, HANS-S showed notable ZOI for both S. aureus and E. coli, which verifies the antibacterial activity of these nanostructures against both Gram-positive and Gram-negative bacteria.
