Researchers Fabricate Solid, Reusable Nanosponges by Adding Boron

A team of scientists from the Rice University and Penn State University has developed a new kind of carbon nanotube material by adding boron to carbon nanotubes.

Rice University graduate student Daniel Hashim holds samples of a carbon nanotube-based sponge that holds great potential for cleaning up oil spills. (Credit: Jeff Fitlow/Rice University)

Boron addition converts carbon nanotubes into solid, reusable nanosponges by promoting the covalent bond formation. These reusable blocks can absorb oil from water. Daniel Hashim, a student of Pulickel Ajayan from the Rice University, informed that these nanosponges are both oleophilic and superhydrophobic. These reusable blocks, which contain over 99% air, allow electrical conductance and can easily be controlled using magnets.

Test results on the sample of the new carbon nanotube material confirmed its reusability. The sample retained its elasticity even after nearly 10,000 compressions, said Hashim. The material can be utilized for oil storage for later recovery. The nanosponge’s available volume is huge as it has ultra-low density, enabling the material to absorb over hundred folds its weight in oil.

Ajayan informed that defects introduced by the addition of boron made the nanotubes to form bonds at the atomic scale, resulting in a complex network. The researchers were the first to demonstrate the formation of covalent bonds between nanotubes to make such solids. The reactions occur when the nanotubes grow, and the product emerges from the furnace as a solid cross-linked porous network. Nano building blocks can be created easily but to obtain the macroscale, the nanotubes must be welded together or they must be linked by forming topological defects.

Mauricio Terrones from the Penn State University explained that the team added boron by knitting the material into the nanotube fabric at very high temperatures. Besides environmental cleanup and oil-spill remediation applications, the nanosponges can be used as scaffolds for regenerating bone tissues, as membranes for filtration, and for making high-efficient lightweight batteries. These materials can even be utilized with polymers to produce stronger and lighter composites for aircraft and automobile industries.


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