Highly Sensitive Surface-Enhanced Raman Scattering (SERS)- Based Multi Gas Sensor : Au Nanoparticles Decorated on Partially Embedded 2D Colloidal Crystals into Elastomer

摘要

Advent of surface-enhanced Raman spectroscopy (SERS) has engendered, the attention to exploit a facile, cost effective, 2D self-assembly based architecture for sensing. Here, Au nanoparticles are decorated on controlled morphology of 2D polystyrene colloidal crystals (PSCCs), partially embedded into flexible polydimethylsiloxane elastomer. Self-assembled flexible hexagonally close-packed PSCCs form the 75 and 25 nm voids in the 500 and 200 nm, PSCCs monolayers and act as an effective plasmonic propagator for SERS sensors signal. Optical and sensing response investigates with UV-Vis and Raman spectroscopy after the exposure of Au NP/2D PS CC/PDMS to NH3, H2O2, N2O and H2S gases environment. The increase in the SERS intensity at 491 cm~(-1) for the 200 nm, CCs based sensors as compared to 500 nm, indicates that the sensing response, strongly dependent on the CCs size. The red-shift in the UV-Vis spectra and enhancement in intensity of SERS designate that H2S forms the maximum Au NPs aggregates over the all tested gases. The chemisorptions on the phenyl ring, due to B2 symmetric modes of the PSCCs with orthogonal polarizability of Au NPs, act as a hot spot for higher sensing response for the detection of gaseous precursors with higher SERS sensitivity and reliability.