Ionic liquids Regulating Interfacial Nanobubble Dynamic Behaviors during Hydrogen Evolution Reaction

Abstract

The dynamic behaviors of interfacial nanobubbles play a pivotal role in determining the efficiency of hydrogen evolution reaction (HER), yet their regulation remains a significant challenge. Ionic liquids (ILs), with their exceptional interfacial properties and broad applications in electrochemistry, offer a promising avenue for tuning nanobubble behaviors during HER. In this study, we employed nanoelectrodes to manipulate the generation of individual H₂ nanobubble and investigated the effects of two ILs ([Bim][HSO₄] and [Bmim][HSO₄]) on nanobubble behavior through electrical signal monitoring and molecular simulations. The results show that H₂ nanobubble needs a higher critical nucleation concentration in [Bim][HSO₄] solution than that in [Bmim][HSO₄] solution, suggesting a pronounced inhibitory effect of [Bim][HSO₄] on nanobubble nucleation. Furthermore, nanobubbles in [Bim][HSO₄] exhibited distinctive interfacial characteristics, including smaller contact angles and greater heights, which facilitate their growth and aggregation. Density functional theory and molecular dynamics simulations confirmed that compared with [Bmim][HSO₄], the stronger adsorption of [Bim][HSO₄] at the electrode interface enhances the hydrophilicity, altering the nucleation and growth behaviors of nanobubbles. This research provides a mechanistic understanding of H₂ nanobubble behavior in IL systems, offering new strategies for optimizing interfacial processes in electrochemical applications.