Multifunctionality of silver closo-boranes

Abstract

Silver compounds share a rich history in technical applications including photography, catalysis, photocatalysis, cloud seeding and as antimicrobial agents. Here we present a class of silver compounds (Ag$_2$B$_{10}$H$_{10}$ and Ag$_2$B$_{12}$H$_{12}$) that are semiconductors with a bandgap at 2.3 eV in the green visible light spectrum. The silver boranes have extremely high ion conductivity and dynamic-anion facilitated Ag$^+$ migration is suggested based on the structural model. The ion conductivity is enhanced more than two orders of magnitude at room temperature (up to 3.2 mS cm$^{−1}$) by substitution with AgI to form new compounds. Furthermore, the closo-boranes show extremely fast silver nano-filament growth when excited by electrons during transmission electron microscope investigations. Ag nano-filaments can also be reabsorbed back into Ag$_2$B$_{12}$H$_{12}$. These interesting properties demonstrate the multifunctionality of silver closo-boranes and open up avenues in a wide range of fields including photocatalysis, solid state ionics and nano-wire production