Treatment with a superacid causes boron nitride layers to separate and become positively charged, allowing them to interface with other nanoparticles, like gold. Image: Berry, et al.Researchers at the University of Illinois at Chicago (UIC) have discovered a route to altering boron nitride, a layered two-dimensional (2D) material, so that it can bind with other materials, like those found in electronics, biosensors and airplanes, for example. Being better able to incorporate boron nitride into these components could help dramatically improve their performance.
The scientific community has long been interested in boron nitride because of its unique properties – it is strong, ultrathin, transparent, insulating, lightweight and thermally conductive – which, in theory, makes it a perfect material for use by engineers in a wide variety of applications. However, boron nitride's natural resistance to chemicals and lack of surface-level molecular binding sites have created difficulty when attempting to interface it with the other materials used in these applications.
UIC's Vikas Berry and his colleagues are the first to report that treatment with a superacid causes boron nitride layers to separate into atomically thick sheets. This treatment also causes binding sites to form on the surface of the sheets, providing opportunities for them to interface with nanoparticles, molecules and other 2D nanomaterials like graphene. It could also allow boron nitride to be used for insulating nano-circuits. The researchers report their findings in a paper in ACS Nano.
"Boron nitride is like a stack of highly sticky papers in a ream, and by treating this ream with chlorosulfonic acid, we introduced positive charges on the boron nitride layers that caused the sheets to repel each other and separate," explained Berry, associate professor and head of chemical engineering at the UIC College of Engineering and corresponding author of the paper.
He added that "like magnets of the same polarity," these positively charged boron nitride sheets repel one another. "We showed that the positive charges on the surfaces of the separated boron nitride sheets make it more chemically active. The protonation – the addition of positive charges to atoms – of internal and edge nitrogen atoms creates a scaffold to which other materials can bind."
According to Berry, the opportunities for boron nitride to improve composite materials in next-generation applications are vast. "Boron and nitrogen are on the left and the right of carbon on the periodic table and therefore boron-nitride is isostructural and isoelectronic to carbon-based graphene, which is considered a 'wonder material',". This means these two materials are similar in their atomic crystal structure (isostructural) and their overall electron density (isoelectric).
"We can potentially use this material in all kinds of electronics, like optoelectronic and piezoelectric devices, and in many other applications, from solar-cell passivation layers, which function as filters to absorb only certain types of light, to medical diagnostic devices," Berry said.
This story is adapted from material from the University of Illinois at Chicago, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.