5-Feb-2018: Indian scientists develop world’s thinnest material

A group of Indian scientists have synthesized a two-dimensional material of one-nanometer thickness using a novel method. The nanosheets synthesized by researchers at the Indian Institute of Technology, Gandhinagar, using Magnesium diboride – a compound of boron – represent a two-dimensional material that has never existed before. Such a material can find a range of applications – from next-generation batteries to ultraviolet absorbing films.

A human hair is about 80,000 nanometer wide, while the approximate diameter of human DNA is 2.5 nanometer. 2D planar materials are just a few micron (one-millionth of a meter) long and wide, and their thickness is one nanometer. Such materials are a hot topic of research since the discovery of graphene – a single layer of carbon arranged in a honeycomb – isolated from pencil graphite. The graphene discovery had won the Nobel physics prize in 2010.

Scientists are racing to develop such nanomaterials as they possess unique properties. Graphene, for instance, is 200 times stronger than steel though it is just one atom thick. The quest is to synthesize newer 2D materials which are similar to graphene but made from different elements.

The nanosheets developed by researchers are made of boron atoms arranged in the shape of a honeycomb, using a simple method. Scientists prepared boron-rich nanosheets by an extremely simple method, which merely involves dissolving a boride compound in water and letting it recrystallize for just the right duration of time. Other methods for preparing similar nanomaterial require a deposition from the vapor phase onto a substrate, which is quite expensive and limits the application.

The researchers have shown that a large fraction of Magnesium diboride crystals can undergo dissolution in water under ambient conditions to result in nanocrystal precursors, which recrystallize in a 2D fashion after some time. This non classical recrystallization can be used to obtain a high yield of boron-based nanostructures like nanodots, nanograins, and nanoflakes.

This discovery, according to the researchers, constitutes a fundamental set of findings in the science of Magnesium diboride, a material that has been primarily known for its superconductive properties.

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. Boron has attracted nanotechnology researchers because of its rich properties – low density, high mechanical strength but lighter weight, high thermal resistance, high specific resistance at ordinary temperature, high melting point, ability to absorb neutrons, and high resistance to chemical attacks.

The ability of these boron-based nanostructures to selectively absorb UV radiation makes them promising candidates for developing transparent UV absorbing films. These functionalized magnesium boride nanostructures (containing hydrides, oxides, and hydroxide functional groups) are also promising candidates for engineering hydrogen storage materials.

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. Scientists are now working towards utilizing these nanosheets for developing the next generation batteries and Nano-catalysts.