Two-step synthesis of hierarchical Ag/Cu2O/ITO substrate for ultrasensitive and recyclable surface-enhanced Raman spectroscopy applications

Abstract Self-cleanable substrates for surface-enhanced Raman spectroscopy (SERS) provides an environment-friendly and cost-effective route for molecular detections. Hence, recyclable SERS substrates driven by a non-destructive photodecomposition process, especially in the visible range, has drawn much attention. In this work, a novel Ag/Cu2O/ITO nanocomposite structure was designed via a robust, two-step route as a self-cleaning SERS substrate. Pyramidal Cu2O nanoarray was firstly deposited onto ITO glass, and subsequently functioned as a sacrificial template to reduce AgNO3 aqueous solution. The Ag/Cu2O/ITO SERS substrate fabricated via this green, organic-free route was very clean, and demonstrated little background noise. In addition, it also exhibited very high SERS activity, successfully detecting RhB molecules at the level of 10−12 M. After detections, the organic residues can be effectively eliminated via photodegradation with Cu2O-Ag composite acting as a cocatalyst. The basial Cu2O component functioned not only as a photocatalyst, but also an anti-oxidant in this structure, effectively promoting the long-term stability of the substrate. Such clean, stable, highly sensitive and uniform Ag/Cu2O/ITO structure may serve as an ideal recyclable SERS substrate.