New ceramic nano-fiber ‘sponges’ for insulation or water purification
Researchers have developed a sponge-like material made from ceramic nano-fiber. The material has the same heat resistance that makes normal ceramics useful in high-temperature settings, but it is also highly deformable. The highly porous sponges could have numerous uses, from water purification devices to flexible insulating materials. For example, the material could be used as an insulating layer in firefighters’ clothing. Also important, the method the researchers used for producing the sponges is “inexpensive and scalable to make these [sponges] in large quantities”.
The work was a collaboration between the State Key Laboratory of New Ceramics and Fine Processing, the Centre for Advanced Mechanics and Materials, both at Tsinghua University, and the School of Engineering at Brown University.
Ultralight porous nano-structures had been created in various materials, including carbon, polymers, and metals. However, the development of such ultralight structures still remains extremely challenging. Ceramics have good mechanical and chemical stability at high temperatures, but are brittle and sensitive to flaws, which complicates the fabrication of durable and flexible porous ceramic nano-structures. With these results the researchers showed that it is possible to manufacture large-scale three-dimensional sponges based on a variety of oxide ceramic nano-fibers. They did this through an efficient solution blow-spinning process. The resulting ceramic sponges consist of numerous tangled ceramic nanofibers, with densities varying from 8 to 40 mg/cm3.
Besides the thermal insulation possibilities, another use could be in water purification. Titanium dioxide (TiO2) is a well-known photocatalyst used to break down organic molecules; killing bacteria and other micro-organisms in water. The researchers showed that a TiO2 nano-fiber sponge could absorb 50 times its weight in water containing an organic dye. After being under illumination for 15 minutes, the sponge was able to degrade the dye. The water could then be wrung out, making the sponge ready to be reused; something that can’t be done with the TiO2 powders normally used in water purification.
Read more: ScienceAdvances