High-Resolution\nDistance Dependence Interrogation\nof Scanning Ion Conductance Microscopic Tip-Enhanced Raman Spectroscopy\nEnabled by Two-Dimensional Molybdenum Disulfide Substrates

Scanning ion conductance microscopy (SICM) is a powerful\nsurface\nimaging tool used in the electrolytic environment. Tip-enhanced Raman\nspectroscopy (TERS) can give more information in addition to the morphology\nprovided by the SICM by utilizing label-free Raman spectroscopy aided\nby the localized plasmonic enhancement from the metal-coated probes.\nIn this study, the integration of SICM with TERS is demonstrated through\nemploying a silver-coated plasmonic nanopipette. Leveraging a two-dimensional\n(2D) molybdenum disulfide (MoS<sub>2</sub>) as a model system, the\nSICM-TERS enhancement factor was estimated to be ∼10<sup>5</sup>, supported by finite-difference time-domain (FDTD) simulation. Moreover,\nthe subnanometer distance dependence SICM-TERS study reveals the tensile\nstress and structural changes caused by the nanopipette. These findings\nillustrate the potential of SICM-TERS for providing comprehensive\nmorphological and chemical insights into electrolytic environments,\npaving the way for future investigations of electrocatalytic and biological\nsystems.