Fabrication of superhydrophobic porous corundum for underwater gas collection and transportation

Although porous ceramics with well-defined submicron pores have garnered research interest, controlling porosity remains challenging. In this study, porous corundum was successfully prepared via a compacting–hydration approach, wherein ρ-Al 2 O 3 was molded, hydrated to homogenize the structure, and finally heat-treated. After hydrophobic modification with methyltrimethoxysilane, the prepared porous corundum was used for active gas capture and transport from water via a diving–floating mechanism. The evolution of crystal phases and microstructures was systematically investigated from room temperature up to 1600 °C. The prepared porous corundum exhibited tunable pore sizes from 151.1 nm to 484.7 nm, which could be controlled by the sintering temperature. The pore size of the corundum is much smaller than that of polymer foams or metal meshes (typically larger than 100 μm) currently used for underwater bubble collection applications, thereby enhancing the material's liquid entry pressure. This work demonstrates that the proposed method for the preparation of porous corundum with controllable submicron pores has potential applications in underwater gas collection.