Nanoscale scanning electrochemical microscopy (SECM) has emerged as a powerful electrochemical method that enables the study of interfacial reactions with unprecedentedly high spatial and kinetic resolution. In this work, we develop carbon nanoprobes with high electrochemical reactivity and well-controlled size and geometry based on chemical vapor deposition of carbon in quartz nanopipets. Carbon-filled nanopipets are milled by focused ion beam (FIB) technology to yield a flat disk tip with a thin quartz sheath as confirmed by transmission electron microscopy. The extremely high electroactivity of FIB-milled carbon nanotips is quantified by enormously high standard electron-transfer rate constants of ≥10 cm/s for Ru(NH3)63+. The tip size and geometry are characterized in electrolyte solutions by SECM approach curve measurements not only to determine inner and outer tip radii of down to ~27 and ~38 nm, respectively, but also to ensure the absence of a conductive carbon layer on the outer wall. In addition, FIB-milled carbon nanotips reveal the limited conductivity of ~100 nm-thick gold films under nanoscale mass-transport conditions. Importantly, carbon nanotips must be protected from electrostatic damage to enable reliable and quantitative nanoelectrochemical measurements.

中文翻译：

---

用于扫描电化学显微镜的聚焦离子束铣削碳纳米电极

纳米级扫描电化学显微镜 (SECM) 已成为一种强大的电化学方法，能够以前所未有的高空间和动力学分辨率研究界面反应。在这项工作中，我们基于石英纳米管中碳的化学气相沉积，开发了具有高电化学反应性和良好控制的尺寸和几何形状的碳纳米探针。碳填充纳米管通过聚焦离子束 (FIB) 技术进行铣削，产生带有薄石英护套的扁平盘尖端，如透射电子显微镜所证实的那样。FIB 研磨的碳纳米尖端的极高电活性通过 Ru(NH3)63+ ≥10 cm/s 的极高标准电子转移速率常数来量化。通过 SECM 方法曲线测量在电解质溶液中表征尖端尺寸和几何形状，不仅可以确定分别低至 ~27 和 ~38 nm 的内部和外部尖端半径，而且还可以确保外部不存在导电碳层墙。此外，FIB 研磨的碳纳米尖端揭示了约 100 nm 厚的金膜在纳米级传质条件下的有限电导率。重要的是，必须保护碳纳米尖端免受静电损坏，以实现可靠和定量的纳米电化学测量。