Extraordinary water adsorption characteristics of graphene oxide

TL;DR

This study reveals that graphene oxide exhibits exceptional water adsorption capacity and rapid adsorption/desorption kinetics due to its unique laminated structure and surface features, surpassing conventional desiccants like silica gel.

Contribution

The paper provides a combined experimental and theoretical analysis of water adsorption in GO, highlighting its high capacity and fast kinetics linked to its microstructure.

Findings

Water uptake of up to 0.58 g/g in GO

Adsorption/desorption rates are an order of magnitude faster than silica gel

High capillary pressure and surface wrinkles facilitate rapid water exchange

Abstract

The laminated structure of graphene oxide (GO) confers unique interactions with water molecules which may be utilised in a range of applications that require materials with tuneable hygroscopic properties. Precise roles of the expandable interlayer spacing and functional groups in GO laminates are not fully understood till date. Herein, we report experimental and theoretical study on the adsorption and desorption behaviour of water in GO laminates as a function of relative pressure. We have observed that GO imparts excellent water uptake capacity of up to 0.58 gram of water per gram of GO (g g-1), which is much higher than silica gel a conventional desiccant material. More interestingly, the adsorption and desorption kinetics of GO is one order of magnitude higher than silica gel. The observed extraordinary adsorption/desorption rate can be attributed to the high capillary pressure in GO laminates as well as micro meter sized tunnel like wrinkles located at the surface.