Confined Electrochemical Behaviors of Single Platinum Nanoparticles Revealing Ultrahigh Density of Gas Molecules inside a Nanobubble

Abstract

Understanding the basic physicochemical properties of gas molecules confined within nanobubbles is of fundamental importance for chemical and biological process. Here we successfully monitored the nanobubble-confined electrochemical behaviors of single platinum nanoparticles (PtNPs) at a carbon fiber ultramicroelectrode in HClO4 and H2O2 solution. Owing to the catalytic decomposition of H2O2, a single oxygen nanobubble formed on individual PtNPs to block the active surface of particle for proton reduction and suppress their stochastic motion, resulting in significantly distinguished current traces. Furthermore, the combination of theoretical calculation and high-resolution electrochemical measurement allowed the size of nanobubble and the oxygen gas density inside a single nanobubble to be quantified. And the ultrahigh oxygen density inside (9286 kg/m3) was revealed, indicating gas molecules in a nanosized space existed with a high state of aggregation. Our approach sheds light on gas aggregation behaviors of nanoscale bubbles using single-entity electrochemical measurement.

Effects of Gas Type, Oil, Salts and Detergent on Formation and Stability of Air and Carbon Dioxide Bubbles Produced by Using a Nanobubble Generator

“…Moreover, microbubbles have been found to be effective in defouling contaminated surfaces [12,13]. Numerous methods have been developed for producing micro/nanobubbles on the surface of large substrates or particles in controlled systems, such as solvent exchange [14], (photo)catalytic reactions [15][16][17][18], electrolysis [19][20][21] and droplet reactions [22,23]. However, when generating micro/nanobubbles in large quantities, maintaining a large volume of water entirely free from impurities becomes an extremely challenging task with respect to studying bubble behavior in pure water.…”