Anomalously low electrostatic bending stiffness of graphene oxide 2D membranes regulates their environmental fate in aquatic ecosystems

Abstract

Though deemed to be of high importance for the determination of environmental impact of 2D materials upon their release into surface waters, control over the conformational engineering of atomically thin membranes remains challenging. This is largely due to our particularly limited understanding of the morphological changes associated with the transformation and transport of such systems in water and sediments. Here we show that contradictory to common belief, the electrostatic contribution plays merely a minor role in the rigidity of graphene oxide (GO), the most studied member of the ever-increasing family of 2D materials. We present evidence that the flat geometry of GO is very persistent in aquatic environments even after the addition of metal ions of different valences positing that 2D membranes pose a more significant threat to the environment than what was envisioned before. This also leads to the revisiting of the century-old Schulze–Hardy rule for the coagulation of low dimensional colloids, resolving the misconception regarding the transformation of 2D membranes into 3D particles.