A new way to create porous materials
24 February 2014
Team of UConn chemists has discovered a new way of making a class of porous materials that allows for greater manufacturing controls and has significantly broader applications than the longtime industry standard.
The process has resulted in the creation of more than 60 new families of materials so far, with the potential for many more. The key catalyst in the process is recyclable, making it a ‘green’ technology.
Suib’s research involves the creation of uniform, or monomodal, mesoporous metal oxides using transition metals such as manganese, cobalt, and iron. Mesoporous describes the size of the pores in the material. In this case, they are between 2 and 50 nanometers in diameter and are evenly distributed across the material’s surface, similar to what one might see if a pin is used to poke numerous holes in a material. Only the UConn process allows scientists to use nitric oxide chemistry to change the diameter of the “pin,” in order to change the size of the holes. This unique approach helps contain chemical reactions and provides unprecedented control and flexibility.
“Professor Suib and his colleagues report an unexpected and novel route to generation of mesoporous metal oxides,” says Prabir Dutta, distinguished university professor of chemistry and biochemistry at The Ohio State University. “Professor Suib’s discovery and the extension of mesoporosity to a much broader range of metal oxides is bound to push this area to new heights, with all sorts of potential applications, making this study a most important development in materials science.”
“Professor Suib and his colleagues report an unexpected and novel route to generation of mesoporous metal oxides...” Prabir Dutta, distinguished university professor of chemistry and biochemistry at The Ohio State University.
Having materials with uniform microscopic pores allows targeted molecules of a particular size to flow into and out of the material, which is important in such applications as adsorption, sensors, optics, magnetic, and energy products such as the catalysts found in fuel cells.
“When people think about these materials, they think about lock-and-key systems,” says Suib. “With certain enzymes, you have to have pores of a certain size and shape. With this process, you can now make a receptacle for specific proteins or enzymes so that they can enter the pores and specifically bind and react. That’s the hope, to be able to make a pore that will allow such materials to fit, to be able to make a pore that a scientist needs.”
UConn’s chemists took a new route, choosing to replace the water-based process with a synthetic chemical surfactant similar to a detergent to create the mesopores. By reducing the use of water, adding the surfactant, then subjecting the resulting nanoparticles to heat, the research team found that it could generate thermally-controlled, thermally-stable, uniform mesoporous materials with very strong crystalline walls. The mesopores, Suib says, are created by the gaps that are formed between the organized nanoparticles when they cluster together. The team found that the size of those gaps or pores could be tailored – increased or decreased – by adjusting the nanostructure’s exposure to heat, a major advancement in the synthesis process.
Perhaps just as importantly, the team found that the process could be successfully applied to a wide variety of elements of the periodic table. Also, the surfactant used in the synthesis is recyclable and can be reused after it is extracted with no harm to the final product.
Suib believes the process will be attractive to industry because it is simple, cost-effective, and green.