Electrochemical Collision of Single Silver Nanoparticles in Carbon Nanopipettes

Exploring the electrochemical collision features at nanoelectrodes is highly desirable for revealing new physical insights and further expanding its applications at smaller spaces. Herein, we study the collision processes of single silver nanoparticles (AgNPs) inside carbon nanopipettes (CNPs). Results show that AgNPs undergo multiple collision and oxidation processes prior to fully oxidation after entering into the CNPs. Different from the disk electrodes, the produced Ag⁺ cannot immediately diffuse away from the cavity and will be reduced once switching to reductive potentials. More intriguingly, we observe discrete cathodic spikes from the Ag⁺ reduction, which are presumably due to the negatively charged carbon surface confined in the CNPs. The elucidated collision features in a CNP would enable its better usage for single entity measurements at confined spaces.