CuxO/Au Chimeric Micro-Nanoparticles for Sensitive SERS Monitoring of Cigarette Smoke via Synergistic Enhancement

Abstract

Surface-enhanced Raman spectroscopy (SERS) has been widely used for trace analyte detection, largely dependent on the design and fabrication of SERS substrates. Among the various types of substrates, hybrid materials that integrate plasmonic metals with functional semiconductors have attracted increasing attention due to their synergistic properties. This study presents the rational design and synthesis of CuxO/Au chimeric micro-nanoparticles as high performance substrates for SERS detection. The hybrids were fabricated via a galvanic replacement reaction, where Cu₂O particles acted as both sacrificial templates and reducing agents for the deposition of Au nanostructures from HAuCl₄ solutions. By systematically varying the HAuCl₄ concentration, the morphology, composition, and interfacial properties of the resulting materials were precisely tuned. The optimized substrate, denoted as CuxO/Au-10, demonstrated remarkable SERS performance, attributed to the synergistic effect of electromagnetic enhancement from Au nanoparticles and chemical enhancement arising from charge transfer at the metal-semiconductor interface. The SERS activity was rigorously evaluated using nicotine as a probe molecule, showing high detection sensitivity. Furthermore, the practical applicability of the substrate was successfully demonstrated in a dynamic puff-by-puff analysis of tobacco smoke from both conventional cigarettes and heated tobacco products (HNB). SERS detection revealed significantly more complex and intense spectra for traditional cigarette smoke compared to the smoke from HNB cigarettes. This highlights the sensitivity and utility of CuxO/Au chimeric micro-nanoparticles for dynamic chemical analysis. This work not only offers a tunable synthesis strategy for high-performance SERS substrates but also paves the way for their application in complex environmental and analytical scenarios.