Novel micro‐spherical Si ₃ N ₄ nanowire sponges from carbon‐doped silica sol foams via reverse templating method

Abstract A novel kind of nanowire sponges, namely Si ₃ N ₄ nanowire‐weaving microspheres, synthesized from a simple, convenient, high‐efficient approach are proposed here. As the reverse template, three‐dimensional foam skeleton structure with uniform pores and ultrathin pore walls is constructed via the effective particle‐stabilized foam method, where the silica sol and carbon black are chosen as the raw materials, providing the sufficient space for the growth of nanowires during the carbothermal reduction reaction process. The formation mechanism of this novel sponge is studied via multiple characterization methods. Si ₃ N ₄ nanowires formed microspheres possess uniform and curving morphology due to the stable environment for growing via vapor–solid mechanism, leading to the relatively high specific surface area of 86.77 m ² /g. Owing to in‐situ oxidation process, micro‐spherical SiO ₂ nanowire sponges with similar morphology are synthesized, which present diameter in range of 20‐40 nm and specific surface area of 50.47 m ² /g. This work provides insights for the design of high‐performance nanowire sponges with promising applications in the filtration, thermal insulators, and catalyst supports fields.