The smallest electrochemical bubbles

• 成果类型: Article
• 署名作者: Gadea, Esteban D.; Sirkin, Yamila A. Perez; Molinero, Valeria; Scherlis, Damian A.
• 署名单位: University of Buenos Aires; Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET); Utah System of Higher Education; University of Utah
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11818
• DOI: 10.1073/pnas.2406956121
• 发表日期: 2024-10-02
• 关键词: nanobubbles; nucleation; nanoparticles; STABILITY; catalysts; carbon

摘要

Many of the relevant electrochemical processes in the context of catalysis or energy conversion and storage, entail the production of gases. This often implicates the nucleation of bubbles at the interface, with the concomitant blockage of the electroactive area leading to overpotentials and Ohmic drop. Nanoelectrodes have been envisioned as assets to revert this effect, by inhibiting bubble formation. Experiments show, however, that nanobubbles nucleate and attach to nanoscale electrodes, imposing a limit to the current, which turns out to be independent of size and applied potential in a wide range from 3 nm to tenths of microns. Here we investigate the potential-current response for disk electrodes of diameters down to a single-atom, employing molecular simulations including electrochemical generation of gas. Our analysis reveals that nanoelectrodes of 1 nm can offer twice as much current as that delivered by electrodes with areas four orders of magnitude larger at the same bias. This boost in the extracted current is a consequence of the destabilization of the gas phase. The grand potential of surface nanobubbles shows they can not reach a thermodynamically stable state on supports below 2 nm. As a result, the electroactive area becomes accessible to the solution and the current turns out to be sensitive to the electrode radius. In this way, our simulations establish that there is an optimal size for the nanoelectrodes, in between the single-atom and similar to 3 nm, that optimizes the gas production.