Silicon nanowire-based energetic materials with significantly improved hygroscopicity

The large energy release potential and highly adjustable combustion characteristics of nanostructured silicon compounded with sodium perchlorate (NaClO 4 ) make it one of the most attractive inorganic energetic materials. Compared with nanoporous silicon, the silicon nanowires prepared by metal-assisted chemical etching are easily loaded with NaClO 4 to obtain energetic materials, due to their one-dimensional array structure and tight contact with the silicon substrate. However, the high hygroscopicity of NaClO 4 greatly degrades the long-term storage property of the material, and must be addressed. In this study, sulfur, as a known stable and non-hygroscopic oxidant that reacts with nanostructured silicon, was impregnated on the silicon nanowires/NaClO 4 energetic material to insulate NaClO 4 from H 2 O in the ambient air. After sulfur impregnation, the mass of the sample increased by 8.7 ​mg after being exposed to 98% relative humidity at 25 ​°C for 12 ​h, while the sample without sulfur increased by 50 ​mg, indicating significant improvement in the hygrophobicity of the sulfur-containing energetic material. Laser ignition experiments showed that the combustion performance was only slightly affected after sulfur treatment. This work provides a new strategy for improving the hygrophobicity of silicon-based energetic materials, which can improve their applicability in micro-electromechanical systems.