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Vanishing Air-Bubble Layer & Ion Adsorption on Graphene in Aqueous Media

13 June 2019

New research from Bristol chemists has important implications for how graphene is used.

Potential applications of graphene in bioanalytic devices and functional composites have recently attracted wide attention. For these applications, graphene often needs to be exposed to, or in intimate contact with, aqueous systems containing ions and bio(macro)molecules.

Understanding the surface structure of graphene in aqueous media is, therefore, important. Several studies on the interactions between biomolecules and graphene and its derivatives in aqueous media have been reported. However, the methods employed in these studies provided limited structural information on the adsorbed molecular layer at the buried graphene-water interface.

Using X-ray reflectivity (XRR) at European Synchrotron Radiation Facility (ESRF, France), Master by Research student Ms Liangzhi Zhou and Wuge Briscoe, along with PhD student Nicholas Taylor (Infineum-Everett jointly funded), former CONYCAT research fellow Dr Luisa Islas, and collaborators at ESRF and Procter & Gamble, revealed the presence of a diffuse air-bubble layer on CVD graphene when it was submerged in water. The air-bubble layer then diminished, and the graphene-water interface would become enriched with ionic species from the aqueous media.

These unprecedent results have important implications to bioanalytic and nanotechnological applications of graphene in which its dynamic interfacial structure in contact with electrolyte solutions is crucial. The results are reported in journal Carbon, and featured in Science Trenda global online platform for latest research findings.

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