A novel approach for the fabrication of SERS substrates based on 3D urchin-like TiO2@Gr–AuNPs architecture

3D urchin-like titanium dioxide@graphene–gold nanoparticles (UT@Gr–AuNPs) architectures with a core@shell structure of UT@Gr were successfully synthesized on silicon substrates via thermal chemical vapor deposition (CVD) technique using sodium deoxycholate surfactant (SDC) as a carbon source, followed by depositing AuNPs onto the surface of UT@Gr via a cold plasma (CP) process. The as-prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and ultraviolet-visible (UV-vis) spectroscopy. Thanks to the hot spots created by the AuNPs onto the surface of UT@Gr, the UT@Gr–AuNPs SERS substrates show significantly enhanced SERS sensitivity to detect hazardous pollutants and pesticide residue substances, e.g., rhodamine 6G (R6G) and malathion with a low detection limit (LOD) of about 5.86 × 10⁻¹¹ M and 2.87 × 10⁻⁸ M, respectively. Moreover, these SERS substrates prepared in this study effectively enable in situ SERS monitoring of the R6G and rhodamine B (RhB) photodegradation reaction and self-cleaning performance under ultraviolet light (UV, 254 nm) irradiation.