Electrodeposited Gold Probe for Electrochemical Scanning Tunneling Microscopy

Direct measurements at the solid-liquid interfaceon thenanometer scale provide information about various physical and chemicalprocesses from both fundamental and applied aspects. Electrochemicalscanning tunneling microscopy (EC-STM) is a powerful tool that makesit possible to perform STM measurements at the solid-liquidinterfaces. However, EC-STM remains challenging due to the difficultyof fabricating the probe for tunneling current measurements in solutions.In this study, we established a novel and versatile method to easilyfabricate the EC-STM probe with high reproducibility. By electrochemicallydepositing Au on a pyrolytic carbon formed within the glass nanopipettewhich has an aperture of several hundred nanometers, we achieved asufficient insulation with almost 100% probability, which overcomesthe 30-year challenge of previous EC-STM studies. High-quality EC-STMimages could be stably obtained with a yield of >80% using theprobe.It will pave the way for future advanced measurements at a varietyof solid-liquid interfaces, such as single molecule spectroscopyand electronic structure characterizations.