Nanocomposite thin films based on Au-Ag nanoparticles embedded in a CuO matrix for localized surface plasmon resonance sensing

"Available online 08 April 2019"
Nanocomposite thin films, composed of monometallic Au and Ag, and bimetallic AuAg nanoparticles, dispersed in a CuO matrix were prepared, characterised and tested for Localized Surface Plasmon Resonance (LSPR) sensing. The films were deposited by reactive magnetron sputtering, followed by a post-deposition thermal annealing to modify the size and shape of the nanoparticles distribution within the oxide matrix. Regarding the main results of the monometallic systems, the Au:CuO films showed LSPR bands from 800 nm to 650 nm, which reveal a progressive narrowing and a continuous blue-shift with increasing temperature (400–700 °C). The Ag:CuO films evidenced plasmonic bands at about 400 nm for temperatures of 500 °C and above. The bimetallic system, Au-Ag:CuO, showed LSPR bands in the range between those of the corresponding monometallic systems, due to the presence of Ag enriched AuAg alloy nanoparticles, taking part of Janus-like structures in some cases. In terms of LSPR sensing, Au:CuO films revealed the highest values of refractive index sensitivity since the nanoparticles are more exposed to the surrounding environment.
This work was supported by the Portuguese Foundation for Scienceand Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2019; and by the projects NANOSENSING, POCI-01-0145-FEDER-016902, with FCT reference PTDC/FIS-NAN/1154/2014; andNANO4BIO, POCI-01-0145-FEDER-032299, with FCT reference PTDC/FIS-MAC/32299/2017. Manuela Proença acknowledges her PhD grantfrom FCT, with reference SFRH/BD/137076/2018. Joel Borges ac-knowledges FCT for his Post-Doc grant SFRH/BPD/117010/2016.Marco S. Rodrigues acknowledges FCT for his PhD grant with referenceSFRH/BD/118684/2016. The authors would like to thank E. Alves(Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico,Universidade de Lisboa) and N. P. Barradas (Centro de Ciências eTecnologias Nucleares, Instituto Superior Técnico, Universidade deLisboa) for the RBS analysis.
info:eu-repo/semantics/publishedVersion