Nanobubble Nucleation and Dissolution Near the Anatase (101)-Water Interface

In gas-involving (photo)electrochemical systems, nanoscale bubbles generate and enrich near the electrode-liquid interface, influencing interfacial transport and reactivity. However, it remains unclear how the solid-liquid interfacial microenvironment governs nanobubble evolution at the microscopic level. In this work, we perform deep potential molecular dynamics simulations with enhanced-sampling to investigate nucleation, dissolution, and detachment of nitrogen nanobubbles near the anatase (101)-water interface under neutral, acidic, and alkaline conditions. Our results show that the undercoordinated titanium and oxygen sites on the anatase (101) surface promote water dissociation, changing local ionic microenvironments. The resulting free hydroxide ions accumulate near the nanobubble surface, yielding a system-dependent negative zeta potential. The zeta potential of the nanobubble in the anatase-saline system is less negative than in other systems, due to the screening of locally paired sodium and chloride ions near the nanobubble surface. The dissolution barrier of nanobubbles shows a good linear positive correlation with the magnitude of zeta potential. This finding is further supported by the modeling with the Epstein-Plesset equation and the simulated bubble surface charge, as well as the experimental observations from nanoparticle tracking analysis and dynamic light scattering. The nucleation barriers are increased in systems with the anatase (101) surface compared to the anatase-free systems but are less sensitive to the acid-base strength. A significantly lower nucleation barrier in the anatase-saline system is attributed to the salting-out effect. The present study provides insights into nanobubble evolution near solid-liquid interfaces, with implications for bubble management in energy conversion systems.