“…Numerous bubbles derived from aggregation and nucleation of gas species will occupy the catalytic site and passivate the electrode surface, leading to a lower energy conversion efficiency. Due to the wide research and application of nanoparticles, clusters, or even single atoms as the catalyst for gas-evolving chemical processes, the investigation of gas nanobubbles at the nanocatalyst surface, especially concerning their formation, growth, and detachment, has attracted tremendously increasing attention. − Recently, nanoelectrodes have been developed as a unique tool that enables one to quantitatively investigate individual gas nanobubbles. − From the steady state mass (gas solute or precursor) transport at the disk nanoelectrode, critical gas concentrations corresponding to bubble nucleation for different gas species (H 2 , − N 2 , O 2 , CO 2 , and D 2 ) have been established . More interestingly, high temporal resolution electrochemical responses provided valuable insight into the bubble nucleation rate, , lifetime, and dynamic stability. , Despite the above significant advancements, due to the lack of direct visualization of electrogenerated nanobubbles at nanoelectrodes with feasible spatial and temporal resolution, − further deeper understanding of the gas nanobubble at the electrode surface becomes very challenging.…”