Direct Observation of Redox-Induced Bubble Generation and Nanopore Formation Dynamics in Controlled Dielectric Breakdown

While controlled dielectric breakdown (CBD) emerged as a promising method for accessible solid-state nanopore fabrication, there are still significant challenges in understanding the fabrication dynamics due to the lack of in situ cross-reference characterization beyond current monitoring. In this work, we developed a multimodal method for characterizing the dielectric breakdown-based nanopore formation dynamics. With this capability, we observed for the first time the redox-induced bubble generation at the electrolyte-membrane interface. The randomly generated gas bubble would significantly alter the electric field distribution on the membrane surfaces and is an overlooked factor that can contribute to the random distribution of the nanopores. Besides, we also studied the impact of electric field strength on the number and location of nanopore(s) initially formed and after enlargement. We believe that the direct evidence of redox-induced bubble formation and the impact of the electric field on nanopore formation dynamics presented in this work would provide significant experimental insight for further improving the breakdown-based solid-state nanopore fabrication.