One-pot synthesis of near-infrared absorbing silver nanoprisms via a simple photochemical method using an ultraviolet-C light source

Abstract

This study describes a simple one-pot photochemical method to synthesize triangular silver nanoprisms (T-AgNPs), for which a mixture of silver nitrate (AgNO3) and citrate was irradiated with an ultraviolet-C (UVC) lamp reactor. We successfully synthesized T-AgNPs with edge lengths ranging from 50 to 150 nm, showing a significant localized surface plasmon resonance (LSPR) band over a wavelength of 1200 nm. This photochemical reaction appears to be unrestricted by plasmon resonance conditions, allowing for the formation of colloidal T-AgNPs with an LSPR band in the near-IR region. In addition, this new method does not require any highly reactive reducing agents or initially prepared silver seed solution. The reduction of Ag+ ions by citrate is induced by UVC light, and the nascent Ag first undergoes nucleation to form spherical or quasi-spherical silver nanoparticles (S-AgNPs). Subsequently, continuous irradiation with UVC light facilitates the transformation of these S-AgNPs into T-AgNPs. The growth kinetics of the nanoparticles with different reaction conditions were examined using ultraviolet–visible–near-infrared spectroscopy and transmission electron microscopy. This new method offers a simple, efficient, and cost-effective means to synthesize T-AgNPs with near-IR LSPR, contributing to wider applications in the fields of optoelectronics, spectroscopics, photovoltaics, etc.