Scientists create nitride foam that soaks carbon dioxide
Rice University ,Texas, scientists have created light foam from two-dimensional sheets of hexagonalboron nitride (h-BN) that absorbs carbon dioxide.
They discovered freeze-drying hexagonal boron nitride turned it into macro-scale foam that disintegrates in liquids. But adding a bit of polyvinyl alcohol (PVA) into the mix transformed it into a far more robust and useful material.
The foam is highly porous and its properties can be tuned for use in air filters and as gas absorp- tion materials, according to scientist Pulickel Ajayan, Rice University. The polyvinyl alcohol serves as glue. Mixed into a solution with flakes of h-BN, it binds the junctions as the microscopic sheets arrange themselves into a lattice when freeze-dried. The one-step process is scalable, the researchers said.
“Even a very small amount of PVA works,” said co-author and Rice postdoctoral researcher Chandra Sekhar Tiwary. “It helps make the foam stiff by gluing the interconnects between the h-BN sheets - and at the same time, it hardly changes the surface area at all.”
In molecular dynamics simulations, the foam adsorbed 340 percent of its own weight in carbon dioxide. The greenhouse gas can be evaporated out of the material, which can be reused repeatedly, Tiwary said. When coated with PDMS, another polymer, the foam becomes an effective shield from lasers that could be used in biomedical, electronics and other applications,” he added.