Preparation of Low-Density Macrocellular Tin Dioxide Foam with Variable Window Size

Low-density porous tin dioxide (∼0.5 g/cm3) was prepared from a SnCl4/ethanol/H2O mixture and polystyrene (PS) template. Such a low density made the as-synthesized tin dioxide act as a promising target material for laser-induced extreme ultraviolet (EUV) emission. The resulting structure of the as-synthesized tin dioxide (SnO2) was a cellular foam, which was composed of large cells (ca. 103 nm, large macropores) interconnected by windows (ca. 102 nm, small macropores). Scanning electron microscope images showed that SnO2 particles of ∼10 nm constituted the cell wall. The space among particles formed mesopores, which were about 7 nm estimated by nitrogen adsorption−desorption isotherm measurements. Therefore, the as-prepared SnO2 showed a hierarchical porous system from macropores to mesopores. The window size on a submicrometer scale was tunable in the range of ∼480−200 nm by changing the molar ratio of ethanol to SnCl4 in tin source solution from 2:1 to 10:1. By consideration that the windows originated ...