Sluggish and Ion-Resilient Behavior of Interfacial Aqueous Layer on Single-Layer Graphene Oxide: Insights from In Situ Atomic Force Microscopy

Yuyao Zhang ^1,2,3, Tingjie Zhan ⁴, Xinfei Ge ^1,2

⁰Department of Environmental Science, Zhejiang University, Hangzhou 310058, China.

Environmental Science & Technology +

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April 4, 2024

View abstract on PubMed

Summary

Interfacial aqueous layers on single-layer graphene oxide (GO) hydrate slowly, showing resilience to ion strength but expanding with humic acid. This impacts GO

Area Of Science

Environmental Science
Materials Science
Nanotechnology

Background

Interfacial interactions of graphene oxide (GO) are crucial for its environmental behavior.
Single-layer GO's interfacial aqueous layers dictate colloidal properties, but are difficult to study.
Conventional methods like X-ray diffraction are unsuitable for single-layer GO analysis.

Purpose Of The Study

To investigate the dynamic behavior of interfacial aqueous layers on single-layer GO.
To understand the influence of environmental factors like ion strength and humic acid on these layers.
To provide insights into the environmental fate and colloidal behavior of GO.

Main Methods

Utilized atomic force microscopy (AFM) for in situ observation of interfacial aqueous layers.
Real-time monitoring of single-layer GO height changes upon immersion.
Subnanometer-level detection of interfacial aqueous layer height.

Main Results

Observed a gradual increase in single-layer GO height from 1.17 to 1.70 nm over 3 hours, indicating slow hydration kinetics.
Found negligible influence of ion strength on interfacial aqueous layer height, suggesting resilience.
Demonstrated that humic acid significantly increased interfacial aqueous layer thickness, enhancing GO colloidal stability and migration potential.

Conclusions

The hydration kinetics of single-layer GO's interfacial aqueous layer are gradual and distinct from multilayer GO.
Interfacial aqueous layers exhibit resilience to ion strength perturbations due to complex interactions.
Humic acid enhances GO colloidal stability and mobility by increasing interfacial aqueous layer thickness, impacting environmental transport.

Keywords:

atomic force microscopy environmental behavior graphene oxide interfacial aqueous layers single-layer

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