Three dimensional porous Expanded Graphite/Silver Nanoparticles nanocomposite platform as a SERS substrate

Abstract

Surface enhanced Raman spectroscopy (SERS) is a promising technique for food safety, medical diagnostics and bio-sensing applications, and environmental protection. However, high production costs due to need of sophisticated equipments, relatively poor stability of the present substrates and repeatability problems limit the use of SERS as a routine analysis technique. Hybrid SERS substrates composed of noble metal nanoparticles and graphene-based materials have gained a significant importance since they combine the surface plasmon resonance property of the metal nanoparticles, and the ability of acting as a protective layer for metal nanoparticles against oxidation, SERS enhancement through charge transfer mechanism, flexibility, excellent optical permeability and superior mechanical strength of graphene-based materials. Herein, three dimensional (3D) porous expanded graphite (EG) decorated with silver nanoparticles (AgNPs) was fabricated as a low cost and easy-to-produce SERS platform. 3D and highly porous structure of the EG/AgNPs nanocomposites provided fast penetration of solvent into the substrate, eliminating coffee-ring effect and enabling one to perform fast SERS measurements, as well as allowing to decorate more metal nanoparticles/adsorb more analyte molecules due to high specific surface area. The detection limit of the EG/AgNPs substrates for Rhodamine 6G (R6G) was determined as 10-11 M and the enhancement factor was estimated to be 2.7 × 106. The peaks of 10-11 M R6G was detected even after one month, indicating a high stability and long lifetime of the substrate. This highly stable, sensitive, cost-effective and easy-to-produce EG/AgNPs nanocomposite substrate exhibit a great potential to promote application of SERS for routine analyses.