Preparation of polycrystalline tungsten nanofibers by needleless electrospinning

One-dimensional metal nanostructures are of great interest for applications in electronic and micromechanical devices, solar cells, sensors, and heterogeneous (photo)catalysts. We describe the multigram preparation method for nanoscopic tungsten fibers (diameter 107 ± 49 nm) for the first time. The material was prepared by needleless electrospinning from an aqueous polyvinyl alcohol and silicotungstic acid solution. A green fibrous composite mat was calcined in air to WO₃/SiO₂ fibers and further reduced in forming gas at various temperatures (500–1000 °C). The reduction process proceeded from nanofibrous blue tungsten oxide to mixtures of reduced tungsten oxides with metallic tungsten and finally at 800 °C to pure metallic W in the form of polycrystalline fibers. These nanofibers consist of individual tungsten nanoparticles covered and interconnected by amorphous silica. All prepared materials were characterized by the TG-DSC, TG-DTA, SEM, TEM, STEM-EDS, and XRD methods. This optimized fabrication method could be scaled up to supply ample amounts of metallic tungsten nanofibers for future applications.