Permanent Nanobubbles\nin Water: Liquefied Hollow Carbon\nSpheres Break the Limiting Diffusion Current of Oxygen Reduction Reaction

Porous liquids have traditionally\nbeen designed with\nsterically\nhindered solvents. Alternatively, recent efforts rely on dispersing\nmicroporous frameworks in simpler solvents like water. Here we report\na unique strategy to construct macroporous water by selectively incorporating\nhydrophilicity on the surfaces of hydrophobic hollow carbon spheres\n(HCS). Specifically, we show that the stable dispersion surface ionized\nHCS in water while retaining the inherent porosity. The electrocatalytic\nconversion of small gas molecules in aqueous electrolytes is limited\nby the concentration and diffusion rates of gas molecules in water.\nIn this case, macroporous water exhibited 6 times gas uptake compared\nto nonporous (pure) water. By leveraging the high gas capacity and\nenhanced diffusion kinetics, the limiting diffusion current of oxygen\nreduction reaction (ORR) in macroporous water is 2 times that in nonporous\nwater, offering promising prospects for sustainable energy conversion\ntechnologies.