Synthesis, Morphological Control, and Antibacterial Properties of Hollow/Solid Ag₂S/Ag Heterodimers

Abstract

Ag(2)S and Ag are important functional materials that have received considerable research interest in recent years. In this work, we develop a solution-based synthetic method to combine these two materials into hollow/solid Ag(2)S/Ag heterodimers at room temperature. Starting from monodisperse Cu(2)O solid spheres, CuS hollow spheres can be converted from Cu(2)O through a modified Kirkendall process, and the obtained CuS can then be used as a solid precursor for preparation of the Ag(2)S/Ag heterodimers through ion exchange and photo-assisted reduction. We have found that formation of the Ag(2)S/Ag heterodimers is instantaneous, and the size of Ag nanocrystals on the hollow spheres of Ag(2)S can be controlled by changing the concentration and power of reducing agents in the synthesis. The growth of Ag nanoparticles on hollow spheres of Ag(2)S in the dimers is along the [111] direction of the silver crystal; the light absorption properties have also been investigated. Furthermore, coupling or tripling of Ag(2)S/Ag heterodimers into dumbbell-like trimers ((Ag(2)S)(2)/Ag, linear) and triangular tetramers ((Ag(2)S)(3)/Ag, coplanar) can also be attained at 60 degrees C by adding the bidentate ligand ethylenediamine as a cross-linking agent. To test the applicability of this highly asymmetric dipolar composite, photocatalytic inactivation of Escherichia coli K-12 in the presence of the as-prepared Ag(2)S/Ag heterodimers has been carried out under UV irradiation. The added Ag(2)S/Ag heterodimers show good chemical stability under prolonged UV irradiation, and no appreciable solid dissolution is found. Possible mechanisms regarding the enhanced antibacterial activity have also been addressed.

A functionalized surface modification with vanadium nanoparticles of various valences against implant-associated bloodstream infection

“…17,47 As reported, disruption to the membrane electron-transport chain will cause toxicity to bacteria. 18,48 This is similar to the vanadium-induced toxicity on cellular mitochondria. 46,49 As discussed earlier, the exposure of bacteria to V metal, V 2 O 3 , VO 2 , and V 2 O 5 nanofilms may elevate intracellular ROS levels and thus cause oxidative stress and damage.…”

Periodic AuAg‐Ag2S Heterostructured Nanowires

“…The room-temperature diffusion of metals (e.g., Au) into semiconductors to form metal-semiconductor pairs generally occurs at the nanometer scale when the semiconductor band-gap energy is lower than about 2.5 eV. [ 16,17 ] Figure S5 showed the simplifi ed band structures of Ag 2 S. The band gap is about 0.9 eV for bulk Ag 2 S crystal at room temperature, and 1.4-2.3 eV for those nanostructured Ag 2 S. [ 24 ] As a result, the diffusion of metals (Au and Ag) in the AuAg-Ag 2 S nanowires agrees with the aforementioned diffusion criteria. The Ostwald ripening between the initially formed Ag 2 S grains can occur because of the diffusion of metals, so that larger segments grow at the expense of nearby smaller grains.…”

Ambient synthesis of a multifunctional 1D/2D hierarchical Ag–Ag2S nanowire/nanosheet heterostructure with diverse applications

“…23 and 514-531 nm of the Ag 2 S/Ag heterostructures. 7 The weak SPR observed herein indeed suggested that the good contact between the Ag 2 S and Ag segments might ensure an effective charge transfer across the phase boundary, and changes in the structure and shape of the product. When the time was increased to 8 h, the SPR absorption bands of the Ag NWs almost disappeared owing to their further sulfuration, and the characteristic absorption feature of Ag 2 S moved to the longer wavelength region at around 515 nm.…”