Graphene hybrid brings new opportunities for sensors

Credit: Technical University of Munich

Graphene is considered by the scientific community as a miracle substance by itself. Imagine what a graphene-porphyrin hybrid will do.

A team of researchers from the Technical University of Munich (TUM) has successfully linked graphene with porphyrin – an essential chemical group that is mostly known for their role in photosynthesis. The hybrid structure can now be used in a variety of applications, including molecular electronics, sensors and catalysis.

Graphene has been the center of attention of much of today’s research because of its peculiar properties. This extremely thin, transparent, and flexible material with very high conductivity and tensile strength has a lot of potential uses. However none of these uses includes capturing solar energy or sensing gas. This could change if graphene is fused with another group of functional molecules.

Before, attaching molecules to graphene via wet chemical methods was the main concern. Wilhelm Auwärter, professor of Molecular Engineering at Functional Interfaces has a new solution to this problem. His team used silver as a catalyst to methodically link graphene to porphyrin molecules in an ultra-high vacuum. The porphyrin molecules lose hydrogen atoms when heated which means they are now free to bond with graphene.

Professor Auwärter explains that their new method leads to a controllable and clean environment. He adds that they can now see exactly how the molecules bond and also the type of bonds that occurred. The chemical structure of individual molecules (also known as the atomic “skeletons”) are depicted through the use of a cutting-edge atomic force microscopes.

“We want to modify only the edges of the material; this way the graphene’s positive properties are not destroyed,” says Auwärter. This is the first time functional molecules were attached to the edges of graphene via covalent bond.

Porphyrin’s own unique properties make it a suitable partner for graphene. “For example, porphyrins are responsible for transporting oxygen in hemoglobin,” he continues. The molecules can take on various tasks based on which metals are at their center. This means it is possible to “reprogram” the material as needed.

The new method by Auwärter’s team could be further enhanced to bond graphene to other molecules. Another improvement in the future would be better reaction control which will lead to attaching molecules to graphene ribbons. These carbon nanostructures are essential in the electronics industry.

More information can be found at: Technical University of Munich.


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