Extraordinary water adsorption characteristics of graphene oxide.

B Lian,M Yoshimura,S Alwarappan,S C Smith,R K Joshi,G Leslie,Y You,S De Luca,V Sahajwalla

doi:10.1039/c8sc00545a

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. The precise role of the expandable interlayer spacing and functional groups in GO laminates has not completely been understood to date. Herein, we report the experimental and theoretical investigations on the adsorption and desorption behaviour of water in GO laminates as a function of relative pressure. We observed that GO imparts high water uptake capacity of up to 0.58 gram of water per gram of GO (g g-1), which is significantly higher than silica gel as a conventional desiccant material. More interestingly, the adsorption and desorption kinetics of GO is five times 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.

Highlights

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
More recent advanced desiccant materials, such as MIL-type metal–organic frameworks (MOFs), have shown signi cant advancement in water adsorption capacities, yet their nancial viability is relatively low for large productions.[9,10]
Due to the larger proportion of hydrophilic functional groups, membrane-like GO prepared by vacuum ltration exhibits high adsorption capacity, which is at least two times higher than that of a conventional desiccant material such as silica gel across the tested range of relative pressure

Summary

Introduction

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. Their hydrophobic characteristics restrict the entry of water molecules into the pores of these materials.[23] On the other hand, due to the larger proportion of hydrophilic functional groups, membrane-like GO prepared by vacuum ltration exhibits high adsorption capacity, which is at least two times higher than that of a conventional desiccant material such as silica gel (pore size 2–6 nm) across the tested range of relative pressure.

Results

Conclusion