A $10 bet made by a Penn State professor against a colleague that his proposed method of splitting the nanoscale sheet of the "wonder material" graphene away from graphite will work has given birth to a new technique that could lead to industrial-scale graphene production.
Graphene is a tightly packed single layer of pure carbon with remarkable strength 100 times than that of the steel. It also the most efficient material for conducting heat and electricity giving it a number of potential uses in a wide array of industries such as in electronics, energy storage and engineering as well as in the development of lightweight but remarkably strong materials.
Unfortunately, sheets of graphene do not exist in nature so they have to be created. Currently known methods of achieving this, however, pose problems such that they increase costs or that they yield low quality results.
In a study published in the journal Nature Chemistry on Sept. 7, Thomas Mallouk, from the Department of Chemistry of The Pennsylvania State University, and colleagues described a new synthetic graphene method that could potentially be used to mass-produce high-quality sheets of graphene. The method called "intercalation" involves introducing a different molecule or ion into the graphite to split it apart into sheets.
Although the intercalation of graphite is already known since 1841, it involved a reducing or oxidizing agent that causes damage to the sought-after properties of the material. For their technique, the researchers used non-oxidizing agents.
It is actually the leaving out of the oxidizing agent on graphite that Mallouk won in his bet with his colleague Nina Kovtyukhova, who in 1999 came up with one of the most widely used methods of intercalating graphite with oxidation.
"If the reaction didn't work I would owe her $100, and if it did she would owe me $10," Mallouk related. "I have the ten dollar bill on my wall with a nice Post-it note from Nina complimenting my chemical intuition."
Mallouk and colleagues wrote that their method used a group of non-oxidizing Brønsted acids which include sulfuric, dichloroacetic phosphoric and alkylsulfonic acids and that the X-ray photoelectron and vibrational spectra showed that the process did not oxidize nor reduce the graphene layers.
"Graphite can be reversibly intercalated by non-oxidizing Brønsted acids," the researchers wrote. "The products are mixtures of graphite and first-stage intercalation compounds. The intercalated graphites readily exfoliate in dimethylformamide to give suspensions of crystalline single- and few-layer graphene sheets."
