New Delhi: How thin can the thinnest material be? It can be 100,000-times thinner than a sheet of paper – as a group of scientists at IIT Gandhinagar have achieved. Specifically, they have synthesised a two-dimensional material just 1 nanometer (nm) thick.
A single strand of human hair has a thickness of about 80,000 nm. The approximate diameter of the human DNA is 2.5 nm. The nanosheets, however, are just a few millionths of a meter long and wide and are 1 nm thick. Such materials have been a hot topic of research since graphene – a single layer of carbon atoms arranged in a honeycomb lattice – was isolated from pencil graphite, most famously by Andre Geim and Konstantin Novoselov in 2004.
Scientists want to develop such nanomaterials because they possess unique properties. Graphene, for example, is 200 times stronger than steel even though it is just one atom thick. Part of the quest is to synthesise newer 2D materials similar to graphene but made from different elements.
The nanosheets synthesised at IIT-Gn are made of magnesium diboride (MgB2) – a compound of magnesium and boron. This material can find a range of applications, from next-generation batteries to UV-absorbing films.
“We prepared boron-rich nanosheets by a simple method, which involves dissolving a boride compound in water and letting it recrystallise for just the right duration of time,” Kabeer Jasuja of the department of chemical engineering, IIT-Gn, told India Science Wire. “Other methods for preparing similar nanomaterials require a deposition from the vapour phase onto a substrate, which is quite expensive and limits the applications.” The team’s efforts were published in the journal ChemPhysChem.
The researchers have shown that a large fraction of magnesium diboride crystals can dissolve in water under ambient conditions to yield nanocrystal precursors. These precursors crystallise once again in a 2D pattern after some time. The process can be used to obtain a relatively large quantity of boron-based nanostructures like nanodots, nanograins and nanoflakes. According to the researchers, what they have developed constitutes a fundamental set of findings in the study of magnesium diboride, a material already noted for its abilities as a superconductor.
“The method yields an aqueous colloid of these nanosheets, which means that a drop of water from this colloid would contain thousands of ultrathin nanosheets swimming like micro-carpets,” Jasuja said.
Researchers have been attracted to boron in particular for its unique set of properties: low density, high mechanical strength, light weight, high thermal resistance, high specific resistance at ordinary temperature, high melting point, ability to absorb neutrons and high resistance to chemical attacks.
So, the ability of these boron-based nanostructures to selectively absorb UV radiation, for example, makes them promising candidates for developing transparent UV-absorbing films. Functionalised magnesium boride nanostructures containing hydride, oxide and hydroxide functional groups will also be of interest to engineers working on building hydrogen storage structures.
“The rich chemistry of boron is expected to make these nanosheets useful for not only storing energy but also for generating energy in a green way. We are now working towards utilising these nanosheets for developing next-generation batteries and nanocatalysts,” Jasuja said.
The study was funded under the ‘Fast Track Research Grant for Young Scientists’ awarded by the Science and Engineering Research Board. It also received support from the INSPIRE Faculty Award Research Grant awarded by the Department of Science and Technology and some seed funding from IIT Gandhinagar.
Dinesh C. Sharma writes for India Science Wire. @dineshcsharma