Chemical Reduction Method for Preparation of Silver Nanoparticles on a Silver Chloride Substrate for Application in Surface-Enhanced Infrared Optical Sensors

摘要

A new method for the preparation of silver nanoparticles (AgNPs) onnsilver chloride discs was developed to integrate the unique properties ofnplasmonic nanoparticles into infrared optical sensing technologies. AgNPnlayers exhibiting strong infrared surface enhancement were prepared bynreacting silver chloride discs in a solution containing hydrazine, whichnacts as a reducing agent. The silver ions in the outer layer of the disc couldnbe reduced under proper conditions and the reduced silver coagulated tonform suitable AgNPs for surface-enhanced infrared absorption (SEIRA)nmeasurements. To examine the influences of the reaction solutionncomposition and also to optimize preparation of SEIRA substrates,nfactors such as pH value, reaction time, and concentration of reducingnagent were examined. Results indicated that both the concentrations ofnhydrazine and hydroxide strongly influenced the SEIRA signals. Thenstrongest signals were observed when AgNPs on a AgCl substrate werenprepared by using a reducing solution of 20 mM NaOH with 0.75 mMnhydrazine. Using the optimized substrates, intense SEIRA spectra werenobserved with an enhancement factor around two orders of magnitudencompared to measurements made using conventional sampling tech-nniques.