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A group of researchers have concocted the perfect recipe for a nanoscale sandwich.

Scientists from Rice University have put two slices of atom-thick graphene around nanoclusters of magnesium oxide to give a super-strong, conductive material of expanded optoelectronic properties.

A team led by Rice materials scientist Rouzbeh Shahsavari built computer simulations of the compound and found it would offer features suitable for sensitive molecular sensing, catalysis and bio-imaging.

This new research could help researchers design a range of customizable hybrids of two and three-dimensional structures with encapsulated molecules.

The researchers were inspired by experiments elsewhere in which various molecules were encapsulated using van der Waals forces to draw components together. The Rice-led study was the first to take a theoretical approach to defining the electronic and optical properties of one of those “made” sample— two-dimensional magnesium oxide in bilayer graphene.

“We knew if there was an experiment already performed, we would have a great reference point that would make it easier to verify our computations, thus allowing more reliable expansion of our computational results to identify performance trends beyond the reach of experiments,” Shahsavari said in a statement.

Graphene on its own has no band gap—the characteristic that makes a material a semiconductor. However, the newly created hybrid does have a band gap that could be tunable, depending on the components. The enhanced optical properties are also tunable and useful.

“We saw that while this single flake of magnesium oxide absorbed one kind of light emission, when it was trapped between two layers of graphene, it absorbed a wide spectrum,” Shahsavari said. “That could be an important mechanism for sensors.”

According to Shahsavari, the group’s theory should be applicable to other two-dimensional materials, including hexagonal boron-nitride and molecular fillings.

“There is no single material that can solve all the technical problems of the world,” he said. “It always comes down to making hybrid materials to synergize the best features of multiple components to do a specific job.

“My group is working on these hybrid materials by tweaking their components and structures to meet new challenges,” he added.

The study was published in Nanoscale.  

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