Multiple synergistic charge transfer effect at the three-dimensional Na2Ti3O7 nanoflowers-silver interface with high surface-enhanced Raman scattering activity

초록

In this study, silver (Ag) nanoparticles (NPs) were uniformly deposited onto Na2Ti3O7 nanoflowers (NTF) using magnetron sputtering technology. The nanoflower structure of the NTF not only promotes multiple reflections and scattering but also enhances the density of the electric field induced by Mie resonances, thereby improving the light absorption efficiency. The surface coverage of Ag NPs on the NTF surface were precisely controlled by adjusting the sputtering time, which directly influenced the distribution of surface "hot spots". These factors led to significant surface-enhanced Raman scattering (SERS) enhancement and improved electron transfer performance. p-Aminothiophenol (PATP) was used as a probe molecule to investigate the enhancement capabilities of the NTF-Ag nanosheets, which achieved an enhancement factor of up to 1.82 x 108, highlighting their potential for SERS-based detection. Additionally, the system exhibited multiple synergistic charge transfer (CT) enhancement for cytochrome c (Cyt c), with a lower detection limit (5 nM) and high reproducibility (RSD = 1.3 %). The multipath and multiple synergistic CT associated with plasmon coupling promoted the reduction of Cyt c. Most importantly, the reduced and/or oxidized Cyt c states can be observed by adjusting the coverage of Ag NPs. Both the experimental results and the simulations clearly confirmed that the remarkable SERS enhancement originated from the unique multilayer flower-like structure of the NTF coupled with the optimal coverage of the Ag NPs. This configuration promotes multiple electromagnetic wave reflections and generates a stronger localized electric field, significantly contributing to the observed SERS enhancement.

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