Controlled Chemical Vapor Deposition and Modification of Carbon Layers inside Quartz Nanopipettes

Carbon nanopipettes (CNPs) have attracted much attention in nanoscale electrochemical applications recently, while the carbon structure and surface oxygen-containing groups limit its applications. Herein, we grow the carbon nanotubes (CNTs) inside the quartz nanopipet via the chemical vapor deposition method, and the fabricated carbon nanotube nanopipettes (CNT-NPs) exhibit better electrochemical responses toward biomolecules such as glutathione and ascorbic acid, compared to the conventional CNPs. In addition, the carbon nanopipette can also be easily doped by a chemical reaction with urea, to display positive surface charges and high electrochemical activity for H₂O₂ oxidation/reduction. This work provides an easy way to tailor the surface structure and charges of the deposited carbon inside the pipettes and thus would further promote its broader usage in electrochemical sensing applications in biological fields.