Periodic array structures for MoO3/Ag composites: improving the stability and uniformity for enhanced SERS performance

Abstract

Surface-enhanced Raman scattering (SERS) has attracted considerable attention for its ability to provide molecular fingerprint information with remarkable sensitivity, which makes it a powerful and nondestructive detection technique. In this study, SERS substrates were fabricated by sequentially depositing Ag and molybdenum trioxide (MoO₃) layers onto hexagonally close-packed polystyrene (PS) spheres via radiofrequency magnetron sputtering in an argon plasma atmosphere. The SERS performance of the fabricated MoO₃/Ag/PS films was evaluated by using 4-mercaptobenzoic acid (4-MBA) as a probe molecule. Notably, the SERS intensity of 4-MBA on the MoO₃/Ag/PS substrate remained largely unchanged compared with that on the Ag/PS substrate, despite the increased adsorption distance between the adsorbed molecules and Ag particles, regardless of the excitation light irradiation. These substrates demonstrated high sensitivity and uniformity, achieving a detection limit of 9.5 × 10^-9 M with a relative standard deviation of 5.25 %. Furthermore, the addition of a MoO₃ layer significantly enhanced the storage stability of the substrates by effectively decreasing oxidation of the Ag surface. As a result, the MoO₃/Ag/PS films, combining long-term stability with uncompromised detection sensitivity, exhibit excellent potential for high-sensitivity chemical and biological sensing applications. This study introduces a novel experimental approach and lays the foundation for further advancements in SERS substrate research and development.