Regulating Bubble Nucleation via Gas Cavities on Superhydrophilic Surfaces.

Bubble nucleation is a fundamental process governing scientific and industrial performances across pool boiling heat transfer, electrocatalytic gas evolution, and mineral flotation. Existing interfacial modulation approaches predominantly rely on constructing micro/nanostructures to lower heterogeneous nucleation energy barriers, yet overlook the pivotal contribution of surface-trapped gas cavities, which restricts the achievement of stable, precisely tailored bubble generation and hinders the development of programmable nucleation control. Herein, we fabricated a series of functional superhydrophilic surfaces with rationally designed microstructures via laser etching, which enable effective regulation of bubble nucleation behavior. Quantitative experiments establish a positive dependence of nucleation rate on surface roughness. Mechanistic characterizations and numerical simulations unambiguously demonstrate that trapped gas cavities confined within rough textures act as dominant preferential nucleation sites. At a CO2 supersaturation ratio of 0.90 ± 0.19, rough superhydrophilic surfaces retaining gas cavities exhibit a bubble nucleation rate of approximately 360 cm-2 s-1. Furthermore, bubble nucleation and release remain achievable even at a CO2 supersaturation ratio of 0.29 ± 0.11. Benefiting from the gas-cavity-dominated mechanism, scalable laser-patterned superhydrophilic surfaces are engineered to accomplish spatially localized, on-demand nucleation and directional bubble detachment, affording an effective strategy for precise manipulation of overall bubble dynamics.