Synergistic Effect of Sonication and Electrolysis for Producing Stable Oxygen Nanobubbles

Oxygen nanobubbles (ONBs) have attracted significant attention due to their unique physicochemical properties and potential applications in biomedical, environmental, and energy-related fields. Efficient production of ONBs is the key to further promote their application challenges yet still remains a challenge. In this work, we systematically compared the performance on the stable generation of ONBs between two distinct methods: the conventional electrolysis and a combined sonication–electrolysis approach with a well-designed electrolysis device with separate cathode and anode chambers. Our results demonstrated that electrolysis alone could produce ONBs with a concentration of 2.6 × 10⁷ particles mL^–1 and an X50 (the median indicating that particle sizes below this value accounted for 50% of the total number of particles) size of about 80 nm. In contrast, the synergistic integration of ultrasound and electrolysis significantly improved the yield, achieving a higher concentration of 9.6 × 10⁷ particles mL^–1, albeit with a slightly larger X50 size of about 115 nm. This work provides a feasible strategy for precisely controlling the size and concentration of ONBs, which is critical for their scalable preparation and further applications.