Concept for the superhydrophobic porous reaction container. (a) Illustrations of the preparation process leading to hollow sponges from electrospun fibers. (b) Morphology of the short electrospun fibers images by light microscopy and scanning electron microscopy. (c) Scanning electron micrographs showing the morphology of the hierarchical porous structures of the wall of the SG. Dashed circles with yellow and red color indicate the big and small pores, respectively.