In-situ interface self-assemblies of nanocrystalline Ag2E (E = S, Se, or Te) via chalcogen directional transfer agents

Abstract

Nanocrystalline Ag2E (E = S, Se, or Te) was interface self-assembled in-situ in the heterogeneous microphase via the reaction of aqueous AgNO3 and RE (R = PPh3, PBu3, PCy3 or Py; E = S, Se, or Te) toluene solution at room temperature. Chalcogen directional transfer agents RE were prepared by refluxing in toluene solution for 12 h. The compositions of as-prepared products were characterized by X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The atomic ratios of Ag to S, Se or Te, measured by inductively coupled plasma (ICP) spectroscopy, were 1.98∶1, 2.08∶1 and 2.13∶1, respectively. The morphologies of products were confirmed by transmission electron microscopy (TEM). UV-Visible spectroscopy was used to record the absorption of Ag2E nanocrystallites after removal of the passivated molecules at high temperature (>500 °C). The thermal stability of Ag2E particles passivated by RE (R = PPh3, PBu3, PCy3 or Py) molecules was studied using thermal gravimetric analysis (TGA). The possible mechanism of nanocrystalline silver chalcogenide self-assembly is discussed.