Mapping oxygen in graphene oxide could unlock better materials

Just one atom thick, graphene is the thinnest and strongest material ever measured. It can also conduct electricity and heat extremely well. These remarkable properties have generated interest in using graphene in everything from solar cells and batteries to water filters and sensors. Turning those possibilities into practical technologies, however, requires scientists to understand how changes to graphene’s structure affect the way it behaves.

Sakshi, a PhD student working with Dr. Alexander Moewes at the University of Saskatchewan’s (USask) Department of Physics and Engineering Physics, is helping answer that question. She combined experiments at the Canadian Light Source (CLS) at USask with computer simulations to study graphene oxide, a form of graphene with oxygen-containing parts attached to its surface.

Graphene oxide is an important starting material for producing graphene-based materials on a large scale. But the oxygen-containing parts can attach to different places on its carbon structure, and where they end up depends partly on how the material is made and can also change its properties. In other words, it’s not just how much oxygen is present that matters. Where that oxygen is located matters too.

Sakshi says that while there are many theoretical models of graphene oxide’s structure, there has been little experimental work to determine where the atoms are actually located.

“If it (graphene oxide) has all these exciting potential applications, why isn’t anyone studying the structure itself, when knowing the structure at the atomic level – where the atoms are – will tell you how the atoms are going to behave when you move them from one position to another.”

A material designed to store energy, for example, may need different properties from one intended to filter water.

Using powerful X-rays at the CLS, Sakshi studied a sample about the size of a grain of sand. She then used computer models to see how different arrangements of oxygen would affect its X-ray “fingerprint.” By matching the models to the real results, the team could see how oxygen was arranged in the material.

The researcher found that where the oxygen is located matters. Two types of oxygen-containing parts, called hydroxyls and epoxides, affect graphene oxide differently: hydroxyls change how electrical charge behaves, while epoxides weaken some of the bonds between carbon atoms.

Sakshi also found that these parts prefer to attach to just one side of the material. That leaves about 60 per cent of graphene’s carbon structure undisturbed, helping it retain many of the properties that make graphene useful in the first place.

Sakshi is now studying how different ways of making graphene oxide affect its structure and properties. By better understanding how the manufacturing process determines where oxygen ends up, researchers could gain greater control over the material’s properties and tailor graphene-based materials for applications such as energy storage, sensors, and water treatment.

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Sakshi, Teak D. Boyko, Cristina Ramírez, and Alexander Moewes. "Studying functional groups in graphene oxide with soft X-ray spectroscopy and density functional theory." npj 2D Materials and Applications (2026). https://doi.org/10.1038/s41699-026-00738-6

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