Bulk nanobubbles that disperse in a bulk solution are normally reported to have a size less than 1
μm and can be generated via a number of techniques: electrolysis [
1,
2], agitation dissolution [
3], mixed pressurization [
4], the cyclone shear method and ultrasonic technique [
5–
7]. The tiny bubbles exhibit numerous structural properties that are entirely different from ordinary macrobubbles, including a large specific surface area, low buoyancy and slow rising velocity, high surface zeta potential, high gas solubility and a large amount of hydroxyl radicals generated by bubble collapse [
7–
12]. These unique properties lead to a massive range of current and expected applications of nanobubbles, including, but not limited to, ecological restoration [
9,
13,
14], sewage treatment [
9,
13–
15], biomedicine [
16–
27], aquaculture [
13,
28], plant cultivation [
13,
28,
29], the cleaning industry [
2,
9,
15,
30–
32], the food and beverage industry [
33,
34], interface slip [
35,
36], mineral flotation [
37,
38] and enhanced chemical reactions [
39]. In particular, for ecological restoration and wastewater treatment, nanobubbles have the potential to become a revolutionary technology in the field of environmental protection. One of the most surprising properties of bulk nanobubbles is their unexpected long-term stability, which is essential for their applications but inconsistent with classical theories. Consequently, stability mechanisms and applications of bulk nanobubbles have recently become a hot topic.