Fabrication on AFM Tips for Tip-Enhanced Raman Spectroscopy by Au Nanoparticles Monolayer Film and Electrodeposition

The tip-enhanced Raman spectroscopy integrates the high spatial resolution of scanning probe microscopy (SPM) with the remarkable sensitivity on chemical information recognition of surface-enhanced Raman spectroscopy (SERS), enabling simultaneous acquisition of morphological and chemical imaging of samples. It is well known that the quality of tips become the crucial issue of TERS technology. Therefore, the development on the cost-effective and feasible method for fabricating AFM-TERS tips with stable TERS imaging capabilities is high desired. Herein, a facial approach combining the nanoparticles assembly with electrodeposition has been developed to fabricate AFM-TERS tips. The different fabrication recipes were carefully compared to identify the most suitable approach. Utilizing p-nitrobenzenethiol (pNTP) as the probe molecule, the results revealed that annealing treatment, coupled with the electrochemical deposition of additional outer layers of gold, significantly improved the stability and cleanness of the tips. Annealing at 105°C followed by the electrodeposition of a 10 nm outer layer of gold brought tips with a controllable morphology, featuring a radius of curvature (ROC) of approximately 35 nm, and an enhancement factor of roughly 3.2 × 10⁴. The present results suggested that the approach become one of the promising tools and can be served as a general routine for the cost-effective fabrication of AFM-TERS tips for extending the practical application of TERS technology.