Mechanism of Charged Graphene Substrate Effects on the Stability of Interfacial Nanobubbles: Molecular Dynamics Simulations

Charged solid substrates play a crucial role in influencing the behavior of interfacial nanobubbles, although the underlying mechanisms are not yet fully understood. To explore this process in greater depth, we employed molecular dynamics (MD) simulations to systematically examine the effects of charged graphene on the morphological evolution, solid interface structure, and stability of interfacial nanobubbles, thereby revealing the intrinsic mechanisms. Our findings indicate that as surface charge density increases, the gas-solid interactions gradually diminish while the liquid-solid interactions significantly intensify. This results in a progressive reduction in both the contact angle and radius of the nanobubbles, eventually causing their detachment from the substrate and transformation to bulk-phase nanobubbles. Moreover, the enhanced gas accumulation effect at the solid interface leads to a reduction in the internal pressure of the bubbles, thus improving the stability of the interfacial nanobubbles. Additionally, the increase in the surface charge density elevates the water molecule density at the solid interface, which in turn strengthens the hydrogen bond network of interfacial water molecules, further stabilizing the liquid-solid interface structure. In summary, this study highlights the critical role of surface charge in regulating interfacial nanobubble behavior, providing new theoretical guidance for optimizing electrode materials and controlling bubble behavior in electrochemical systems.