Ultrasensitive Detection and In Situ Imaging of Analytes on Graphene Oxide Analogues Using Enhanced Raman Spectroscopy

Abstract

We demonstrate how algorithm-improved confocal Raman microscopy (ai-CRM), in combination with chemical enhancement by two-dimensional substrates, can be used as an ultrasensitive detection method for rhodamine (R6G) molecules adsorbed from aqueous solutions. After developing a protocol for laser-induced reduction of graphene oxide, followed by noninvasive Raman imaging, a limit of detection (LOD) of 5 × 10 –10 M R6G was achieved using ai-CRM. An equivalent subnanomolar LOD was also achieved on another graphene oxide analogue −UV/ozone-oxidized graphene. These record-breaking detection capabilities also enabled us to study the adsorption kinetics and image the spatial distribution of the adsorbed R6G. These findings indicate a strong potential for algorithm-improved graphene-enhanced Raman spectroscopy as a facile method for detecting, imaging, and quantifying trace amounts of adsorbing molecules on a variety of 2D substrates.

Surface‐Enhanced Raman Scattering Using 2D Materials

“…Nair et al . have used reduced graphene oxide (rGO) fabricated by laser writing, where the GO's functional groups have been removed, to detect R6G molecules, in this case, leading to better results than using the non‐reduced GO sample [63] . Reduced Ti 3 C 3 T x MXene nanosheets (r‐Ti 3 C 3 T x ) were also demonstrated to have higher Raman enhancement for R6G molecules (EF=10 7 ) than the analogous pristine Ti 3 C 3 T x [64] .…”