Al₂O₃-modified surface-enhanced Raman scattering-active gold nanoparticles on substrates by using sonoelectrochemical pulse deposition

As shown in the literature, many methods have been developed to improve signals, reproducibility and stabilities of surface-enhanced Raman scattering (SERS) for their reliable applications. However, the fabrication can be laborious. In this work, we propose a simple pathway to prepare SERS-active substrates with Al₂O₃-modified Au nanoparticles (NPs) by sonoelectrochemical deposition-dissolution cycles (SEDDCs). Based on probe molecules of Rhodamine 6G (R6G), an enhancement factor of 4.4 × 10 ⁸ and a detection limit of 2 × 10^-14 M were observed on the proposed SERS-active substrates. The reproducibility and stabilities of the proposed SERS-active substrates are satisfactory. Also, the prepared Al ₂O₃-modified Au NPs-deposited substrate can markedly improve the thermal stability by raising the operation temperature over 50 C, as compared with unmodified Au NPs-deposited substrate. Meanwhile, aging of SERS effect observed on this proposed substrate is slight in an atmosphere of 50% RH and 20% (v/v) O₂ at 30°C for 60 day.