Researchers are testing an array of new combinations that may vastly expand the options available to create faster, smaller, more efficient energy storage, advanced electronics and wear-resistant materials.
They created 2 entirely new, layered 2D materials using molybdenum, titanium and carbon. “By ‘sandwiching’ one or two atomic layers of a transition metal like titanium, between monoatomic layers of another metal, such as molybdenum, with carbon atoms holding them together, we discovered that a stable material can be produced,” Anasori said. “It was impossible to produce a 2D material having just 3 or 4 molybdenum layers in such structures, but because we added the extra layer of titanium as a connector, we were able to synthesize them.”
It represents a new way of combining elemental materials to form the building blocks of batteries, capacitors and supercapacitors, as well as superstrong composites- like the ones used in phone cases and body armor. “It is safe to say that this discovery enables the field of materials science and nanotechnology to move into an uncharted territory,” Anasori said. Combining 2D sheets of elements in an organized way to produce new materials has been the goal of Drexel nanomaterials researchers for more than a decade. Imposing this sort of organization at the atomic level is no easy task.
“Due to their structure and electric charge, certain elements just don’t ‘like’ to be combined,” But Drexel researchers came up with a way to circumvent this chemistry challenge. It starts with a MAX phase material. They created a stable, 2D, layered material called MXene in 2011 by selectively extracting layers of aluminum atoms from a block of MAX phase by etching them out with an acid. “By putting a MAX phase in acid, we have been able to selectively etch away certain layers and turn the MAX phase into many thin 2-D sheets, which we call MXenes.”
“By adding titanium to the mix we managed to make an ordered molybdenum MAX phase, where the titanium atoms are in center and the molybdenum on the outside. It can use this method to make as many as 25 new materials with combinations of transition metals, such as molybdenum and titanium, that previously wouldn’t have been attempted. Anasori plans to make more materials by replacing titanium with other metals, such as vanadium, niobium, and tantalum, which could unearth a vein of new physical properties that support energy storage and other applications.
APS: “We see possible applications in thermoelectrics, batteries, catalysis, solar cells, electronic devices, structural composites and many other fields, enabling a new level of engineering on the atomic scale.” http://drexel.edu/now/archive/2015/August/sandwich-materials/
Drexel University engineers have created a layered material of molybdenum and titanium by using a new process they invented to etch a MAX phase into a two-dimensional, layered MXene. Credit: Drexel University
Recent Comments