Monitoring nanobubble nucleation at early‐stage within a sub‐9 nm solid‐state nanopore

Nanobubble nucleation study is important for understanding the dynamic behavior of nanobubble growth, which is instructive for the nanobubble applications. Benefiting from nanopore fabrication, herein, we fabricated a sub‐9 nm SiN X nanopore with the comparable size to nanobubbles at early‐stage. The confined nanopore interface serves as a generator for producing nanobubbles by the chemical reaction between NaBH 4 and H 2 O and as an ultra‐sensitive sensor for monitoring the H 2 nanobubble nucleation process. By carrying out the NaBH 4 concentration‐dependent experiments, we found the life‐time of nanobubbles decreased 250 times and the frequency of nanobubble generation increased 38 times with the NaBH 4 concentration increasing from 6 to 100 mM. The long‐time equilibrium between gas molecules inward flux and outward flux could prolong the life‐time of nanobubbles to hundreds of milliseconds at low NaBH 4 concentration. The raw current trace depicted that the transient accumulation and dissolution of cavity occurred during all the life‐time of nanobubbles. Therefore, the sub‐9 nm SiN X nanopore shows a strong ability for real‐time monitoring the nanobubble nucleation at early‐stage with high temporal and spatial resolution. This work provides a guide to study the dynamic and stochastic characteristics of nanobubbles.