Nanosers devices based on Au-studded ZnO nanorod for R6G detection

Abstract

Introduction: The prospect of wielding semiconductor–noble metal hybrid nanomaterials as surface-enhanced Raman scattering (SERS) substrates for the ultrasensitive detection of organic molecules in sensing applications has attracted ever-increasing attention. In this study, nanoSERS devices based on Au-studded ZnO nanorods (Au/ZnO) were fabricated using a facile photochemical deposition method for the detection of low-concentration rhodamine 6G (R6G) molecules. Methods: Analytical techniques such as SEM, EDX, XRD, and UV‒Vis spectroscopy were utilized to investigate the morphology, elemental composition, crystalline structure, and optical absorption of the Au/ZnO nanostructure, respectively. Raman scattering spectroscopy was used to evaluate rhodamine 6G. Results: The results show that vertically well-aligned ZnO nanorods (NRs) were effectively grown on the seeded glass substrate at 90°C for 4 h, and Au nanoparticles (NPs) with a diameter of approximately 20 nm were successfully deposited onto their surface. Comparing the obtained Au/ZnO substrate to the ZnO NRs and glass substrates, it exhibited superior SERS performance with R6G at a low concentration of 10-3 M. Significantly, it was found that the Au/ZnO for the R6G sensitive limit was approximately 10-9 M. This could be explained due to the surface plasmon resonance (SPR)-induced electromagnetic field enhancement of Au NPs as well as the charge-transfer mechanism between the Au/ZnO substrate and adsorbed R6G molecules under 532 nm laser excitation. Conclusion: This work demonstrates the potential SERS activity of Au/ZnO substrates, which can identify organic substances at trace levels using the Raman analysis method.