Hedgehog Inspired CuO Nanowires/Cu2O Composites for Broadband Visible-Light-Driven Recyclable Surface Enhanced Raman Scattering

Self-cleanable surface-enhanced Raman scattering (SERS) spectroscopy affords a promising route toward environment-friendly biosensors for point-of-care diagnostics. It is of great importance to develop recyclable SERS substrates driven by a photocatalytic decomposition process, especially in the visible range. In this work, inspired by the hedgehog-like structures, a broadband visible-light-driven photocatalytic SERS platform with the CuO nanowires (NWs)/Cu2O hetero-nanostructures as the backbone is demonstrated. Via employing the approach of nanosecond laser ablation on Cu sheet coupled with subsequent thermal oxidation, the formed hedgehog-like, high-density, and dual-scale micro/nanostructures not only demonstrate enhanced broadband visible-light-absorption capability even extended to the near infrared range but also exhibit boosted interfacial adhesion with favorable stability. Such phenomena imply that the binary oxidized Cu composites decorated with metallic nanoparticles can serve as high-performance SERS substrates with superior recyclability. Under the visible light illumination, the as-fabricated ternary Ag/CuO NWs/Cu2O composites can be self-cleaned by photocatalytic degradation of adsorbates, thus leading to recyclable SERS substrates, which can preserve more than 85% SERS activity after seven cycles' measurement. These results pave a new path to realize reusable SERS substrates in the applications of remote and resource-limited environments toward next-generation green biosensors.