From faceted nanoparticles to nanostructured thin film by plasma-jet redox reaction of ionic gold

Abstract

Cold-atmospheric plasma-assisted deposition has emerged as an efficient technique for synthesising gold nanoparticles (AuNPs). Here, a plasma-vapour interaction is used for the simultaneous reduction and deposition of AuNPs from an inorganic precursor (HAuCl4). As surface analyses suggest, plasma input power plays an important role in reduction efficiency, whereas argon gas flow rate reduction leads to the formation of smaller particles. This study demonstrates that the presence of ethanol in the reactive mixture of gold promotes improved reduction of gold to nanostructures owing to their volatile properties. A systematic investigation of plasma and the deposited nanostructures reveals that the reduction is mainly caused by the free electrons and in-situ formation of hydrogen peroxide inside plasma. Our method demonstrates that nanostructured thin film can be created within 5 min by controlling plasma parameters. Deposited AuNPs feature advanced plasmonic surface-enhanced Raman scattering responses, tested with Raman marker Rhodamine R6G, enabling their use as a potential substrate for fast and reliable optical analytical biochemical sensing.