Imaging Single H₂ Nanobubbles Using Off-Axis Dark-Field Microscopy

A robust and detailed physicochemical description of electrochemically generated surface nanobubbles and their effects on electrochemical systems remains at large. Herein, we report the development and utilization of an off-axis, dark-field microscopy imaging tool for probing the dynamic process of generating single H₂ nanobubbles at the surface of a carbon nanoelectrode. A change in the direction of the incident light is made to significantly reduce the intensity of the background light, which enables us to image both the nanoelectrode and nanobubble on the electrode surface or the metal nanoparticles in the vicinity of the electrode. The correlated electrochemical and optical response provides novel insights regarding bubble nucleation and dissolution on a nanoelectrode previously unattainable solely from its current-voltage response.