Effect of Surfactant on Electrochemically Generated Surface Nanobubbles.

Surfactants, mimics of contamination, play an important role in nanobubble nucleation, stability, and growth at the electrode surface. Herein, we utilize single-molecule fluorescence microscopy as a sensitive imaging tool to monitor nanobubble dynamics in the presence of a surfactant. Our results show that the presence of anionic and nonionic surfactants increase the rate of nanobubble nucleation at all potentials in a voltage scan. The fluorescence and electrochemical responses indicate the successful lowering of the critical gas concentration needed for nanobubble nucleation across all voltages. Furthermore, we demonstrate that the accumulation of surfactants at the gas-liquid interface changes the interaction of fluorophores with the nanobubble surface. Specifically, differences in fluorophore intensity and residence lifetime at the nanobubble surface suggest that the labeling of nanobubbles is affected by the nature of the nanobubble (size, shape, etc.) and the structure of the gas-liquid interface (surfactant charge, hydrophobicity, etc.).