Recyclable 3D Au NPs@ZnO Nanorods@Inverted Triangular Pyramid Cu as SERS Substrates for Pollutant Detection

The rapid development of surface-enhanced Raman scattering (SERS) technology provides a fast and nondestructive method for food safety detection. However, most noble metal/ZnO as SERS substrates were fabricated on flat surfaces. Research on growing ZnO on micro/nanostructured surfaces as SERS substrates with self-cleaning and high-sensitivity performance is scarce. In our work, Au nanoparticles@ZnO nanorods (nanosheets)@inverted triangular pyramid indentations (Au NPs@ZnO NRs (NSs)@ITP Cu), as a self-cleaning composite SERS substrate, were fabricated by combining nanoindentation, hydrothermal, and magnetron sputtering. First, significant influences on the morphology of the arrayed inverted triangular pyramid indentation structures were observed with variations in the machining parameters. Subsequently, the effects of different hydrothermal parameters on the ZnO nanorods were compared. It was found that a well-defined, single-pyramidal indentation enabled the growth of vertically aligned ZnO nanorod structures. In contrast, a nanosheet-like ZnO morphology was predominantly formed on the overlapped inverted triangular pyramid indentations. Second, compared to the electric field intensities of single Au NPs on the flat Cu surface, the electric field intensities of Au NPs@ZnO NRs@ITP Cu and Au NPs@ZnO NSs@ITP Cu were 50.8 and 33.5 times, respectively. Finally, the Au NPs@ZnO NRs@ITP Cu Tri 2 substrate demonstrated superior SERS performance, enabling the detection of 10^–9 mol/L R6G and 10^–7 mol/L MG. Then, R6G and MG molecules on the SERS substrate were completely degraded after 120 and 30 min of UV–visible irradiation, respectively. This demonstrated the significant potential of recyclable, ultrasensitive SERS substrates for detecting pollutants.