This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Graphene is flat. But that doesn't mean other 2D materials—particularly those containing more than one element—necessarily share the same structure.
In the past, researchers have often simplified these materials by modeling them as perfectly flat sheets. New research from the ARC Center of Excellence for Carbon Science and Innovation (ARC COE-CSI) suggests they've been working from the wrong assumption. Graphitic carbon nitride (g-C₃N₄) is a material attracting considerable interest for its potential to produce hydrogen and break down environmental pollutants.
It has often been treated as if it consisted of perfectly flat atomic sheets, and this flat structure has subsequently become the starting point for numerous studies attempting to predict how the material will behave and how its properties might be modified through the introduction of defects. There's just one problem. "The chemistry and structure of the material determine its properties," says ARC COE-CSI affiliated member and UNSW Canberra Ph.D. student Gbemi Abass.
"If the structure is wrong, the predicted properties will definitely be wrong." Graphene consists entirely of carbon atoms and forms an extraordinarily flat sheet. Graphitic carbon nitride has a related layered structure but introduces another player: nitrogen. These nitrogen atoms change the way the carbon atoms around them interact.
"The structural challenge has been a fundamental issue in graphitic carbon nitride research for a long time," says Abass. "When the structure is viewed from above, it looks perfectly flat. But when it is viewed from the side, it isn't." When the researchers allowed their computer models to move away from the conventional flat arrangement and find a lower-energy—and therefore more stable—structure, the sheets buckled.
Rather than appearing like a perfectly flat sheet of paper, the team found they were more like one with a gentle ripple running through it. The paper is published in the journal Materials Advances. "Previously people had talked about buckling theoretically, but there was a lack of experimental evidence to prove that structure," says ARC COE-CSI Ph.D. researcher Adnan Ahmad from ANU.
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