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.

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The development of a flexible and high-performance humidity sensor is essential to expand its new applications, such as personal health monitoring and early diagnosis. In this work, SnO2/rGO nanocomposites were prepared by one-step hydrothermal method. The effect of rGO-doping on humidity sensing performance was investigated. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy were used to characterize the nanostructure, morphology and chemical composition of SnO2/rGO nanocomposites. The SnO2/rGO humidity sensitive film was prepared by electrospinning on a polyimide film modified with gold electrodes. The humidity test results show that different doping ratios of rGO have different effects on humidity sensing properties. Among them, the sensor with 2 wt% rGO-doping has a high sensitivity (37,491.2%) within the humidity range as well as the fast response time (80 s) and recover time (4 s). Furthermore, the sensor with 2 wt% rGO-doping remains good flexibility and stability in the case of bending (1000 times). The sensitivity of the 2 wt% rGO-doping sensor at the bending radius (8 mm and 4 mm) is 48,219% and 91,898%, respectively. More importantly, the sensor could reflect different breathing states clearly and track breathing intervals as short as 3 s. The SnO2/rGO flexible humidity sensor with accuracy, flexibility and instantaneity as well as the facile fabrication strategy is conceivable to be applied in the potential application for human health real-time monitoring.