Researchers at Northwestern University, Illinois, have broken a world record in the creation of two synthetic materials, named NU-109 and NU-110, which have the greatest amount of surface areas of any material to date. To put this into perspective: if one were able to take a crystal of NU-110 the size of a grain of salt, and somehow unfold it, the surface area would cover a desktop. Additionally, the internal surface area of just one gram of the new material would cover one-and-a-half football fields.
The NU-109 and NU-110 synthetic materials belong to a class of crystalline compounds referred to as metal-organic frameworks (MOFs). MOFs are thought to hold considerable potential as vessels for the transport and storage of natural gas, catalysts, and other sustainable materials chemistry.
The Northwestern University team, led by Omar Farha, research associate professor of chemistry in the Weinberg College of Arts and Sciences, synthesized, characterized, and computationally simulated the behavior of the NU-109 and NU-110 MOFs. The materials were analyzed using the Brunauer-Emmett-Teller (BET) theory and found to measure 7,000 m2/g. This means that one kilogram (2.2 lb) of the new material contains an internal surface area which could cover seven square kilometers (2.7 square miles) – the highest surface areas of any porous material on record.
The scientists gained access to the heretofore unreachable high surface area of the porous NU-109 and NU-110 MOF materials by removing the solvent molecules which were previously trapped within the materials' pores. This was done with the use of a carbon dioxide activation technique, which gently removed the solvent and avoided damaging the MOF materials.
The researchers believe their work may lead to yet further advances in MOF research and they aim to eventually exceed double the current surface area of the NU-109 and NU-110 materials. In order for this to happen, the design of MOFs will require altering on the molecular level: MOFs are composed of organic linkers held together by metal atoms, and this results in a molecular cage-like structure. Therefore, the team propose to use more space efficient linker types in the material’s design.
A paper describing the findings titled “Metal-organic Framework Materials with Ultrahigh Surface Areas: Is the Sky the Limit?” was published August 20 in the Journal of the American Chemical Society and the new MOF-designing and synthesizing tech is currently being commercialized by NuMat Technologies.
Source: Northwestern University
