Facet-Dependent SERS Activity of Co3O4

Surface-enhanced Raman spectroscopy (SERS) is an ultra-sensitive and rapid technique that is able to significantly enhance the Raman signals of analytes absorbed on functional substrates by orders of magnitude. Recently, semiconductor-based SERS substrates have shown rapid progress due to their great cost-effectiveness, stability and biocompatibility. In this work, three types of faceted Co3O4 microcrystals with dominantly exposed {100} facets, {111} facets and co-exposed {100}-{111} facets (denoted as C-100, C-111 and C-both, respectively) are utilized as SERS substrates to detect the rhodamine 6G (R6G) molecule and nucleic acids (adenine and cytosine). C-100 exhibited the highest SERS sensitivity among these samples, and the lowest detection limits (LODs) to R6G and adenine can reach 10(-7) M. First-principles density functional theory (DFT) simulations further unveiled a stronger photoinduced charge transfer (PICT) in C-100 than in C-111. This work provides new insights into the facet-dependent SERS for semiconductor materials.

Automated summary

Surface-enhanced Raman spectroscopy (SERS) is an ultra-sensitive and rapid technique that significantly enhances the Raman signals of analytes absorbed on functional substrates. Recently, semiconductor-based SERS substrates have shown rapid progress due to their cost-effectiveness, stability, and biocompatibility. In this study, different forms of Co3O4 microcrystals were utilized as SERS substrates for detecting specific molecules. C-100 showed the highest SERS sensitivity and the lowest detection limits to the molecules tested. First-principles density functional theory (DFT) simulations revealed a stronger photoinduced charge transfer (PICT) in C-100 compared to C-111.