Implicit Nucleation and Competitive Dynamics of Electrogenerated Hydrogen Nanobubbles
Electrogenerated gas nanobubbles strongly influence the performance of electrochemical energy-conversion systems, yet their nucleation and early evolution remain poorly understood due to limitations of existing experimental and computational approaches. Operando imaging lacks the temporal resolution required to capture nucleation events, while molecular dynamics simulations are restricted to nanometer-scale domains containing at most a few bubbles. Here, we develop a thermodynamically consistent phase-field framework that unifies dissolved gas transport, curvature dependent interfacial thermodynamics, and implicit bubble nucleation within a single continuum description. Using hydrogen nanobubble formation during electrocatalysis as a canonical test case, the model captures nucleation without prescribing nuclei, resolves diffusion-controlled growth under curvature effects, and remains computationally tractable despite hydrogen's extremely low solubility. Simulations reveal how nanobubble nucleation occurs once a local supersaturation threshold is exceeded, triggering a reorganization of the chemical-potential field that focuses dissolved gas toward the nascent bubble. In multi-catalyst systems, overlapping diffusion fields lead to strong bubble-bubble interactions, including competitive growth, Ostwald ripening, and source occlusion. Extending the framework to dispersed catalyst populations shows that nanobubble survival is governed not only by catalyst size but also by spatial arrangement and diffusive competition, such that only a subset of bubbles persist while others dissolve and act as feeders. These results reframe electrogenerated nanobubbles as emergent, spatially organized features rather than unavoidable parasitic byproducts, and point toward electrode designs that deliberately control where bubbles nucleate and grow to preserve active area and mitigate transport losses.