A novel metal–semiconductor SERS self-cleaning system with synergistic effects for highly sensitive detection of pollutants†

Accuracy and reusability are the major concerns in the development of surface-enhanced Raman scattering (SERS) technology. This study reports an Au nano-urchin (Au NU)/TiO₂@ZnO composite self-cleaning SERS substrate for cyclic detection of common pollutants. The SERS substrate increased the Raman scattering signal intensity via simultaneous electromagnetic and chemical mechanisms. The lowest detection limit of the substrate was 10⁻¹² M for methyl blue (MB) molecules. The composite SERS substrate also exhibited outstanding self-cleaning capabilities. It could rapidly degrade MB molecules adsorbed on the surface within 21 min under UV irradiation. A 95% enhancement effect was still maintained after multiple detection-degradation cycles. The chemical enhancement mechanism of the composite SERS substrate was analyzed in detail around the energy band structure, confirming the excellent enhancement effect of the substrate on signaling molecules with different bandgaps. These studies highlighted the superiority of the enhancement mechanism of the substrate, complemented with its photocatalytic self-cleaning properties. Moreover, the components of the substrate interacted with each other and optimally boosted various performances. This study opens up new breakthrough points and broader application prospects for the development of SERS technology.