Role of substrate on interaction of water molecules with graphene oxide and reduced graphene oxide

TL;DR

This study investigates how different substrates influence water interaction with graphene oxide and reduced graphene oxide, revealing substrate-dependent humidity sensitivity and minimal impact of material thickness on electronic properties.

Contribution

It demonstrates the critical role of substrate in water interaction with GO and RGO, and shows that material thickness has little effect on humidity response.

Findings

Pt substrate makes GO and RGO insensitive to humidity changes.

Si3N4 substrate causes significant humidity-dependent behavior in GO and RGO.

Material thickness (1-3 layers) has minor influence on electronic response to humidity.

Abstract

We study local electronic properties of graphene oxide (GO) and reduced graphene oxide (RGO) on metallic (Pt) and insulating (Si3N4) substrates in controlled humidity environment. We demonstrate that the supporting substrate plays a crucial role in interaction of these materials with water, with Pt making both GO and RGO insensitive to humidity variations and change in environment. On the other hand, in the case of Si3N4 substrate a significant difference between GO and RGO with respect to humidity variations is demonstrated, indicating complete water coverage at ~60% R.H for RGO and ~30% R.H. for GO. Irrespective of the substrate, both GO and RGO demonstrate relative independence of their electronic properties on the material thickness, with similar trends observed for 1, 2 and 3 layers when subject to humidity variations. This indicates a relatively minor role of material thickness in GO-based humidity sensors.