Effect of Electrolytic Medium on the Electrochemical Reduction of Graphene Oxide on Si(111) as Probed by XPS.

Andrea G Marrani,Ricardo Schrebler,Enrique A Dalchiele,Robertino Zanoni,Francesco Amato,Alessandro Motta

doi:10.3390/nano12010043

Abstract

The wafer-scale integration of graphene is of great importance in view of its numerous applications proposed or underway. A good graphene–silicon interface requires the fine control of several parameters and may turn into a high-cost material, suitable for the most advanced applications. Procedures that can be of great use for a wide range of applications are already available, but others are to be found, in order to modulate the offer of different types of materials, at different levels of sophistication and use. We have been exploring different electrochemical approaches over the last 5 years, starting from graphene oxide and resulting in graphene deposited on silicon-oriented surfaces, with the aim of understanding the reactions leading to the re-establishment of the graphene network. Here, we report how a proper choice of both the chemical environment and electrochemical conditions can lead to a more controlled and tunable graphene–Si(111) interface. This can also lead to a deeper understanding of the electrochemical reactions involved in the evolution of graphene oxide to graphene under electrochemical reduction. Results from XPS, the most suitable tool to follow the presence and fate of functional groups at the graphene surface, are reported, together with electrochemical and Raman findings.

Highlights

We report a comparative study of the effects of exploiting two different, yet common, electrolyte media in the electrochemical reduction of graphene oxide (GO) layers deposited on crystalline silicon
4 mg mL−1 water dispersion of GO was purchased from Graphenea (Graphenea Headquarters, San Sebastián, Spain), consisting of single layered graphene oxide synthesized with a modified Hummers protocol as indicated by the supplier
Scheme 1 depicts this procedure in the production of electrochemically reduced GO layers on a silicon surface

Summary

Introduction

A two-dimensional (2D), single-layer planar sheet of sp2 -hybridized carbon atoms densely packed in a honeycomb crystal lattice, is considered the first true 2Dmaterial (i.e., one atom thick) to become a keystone in material science research ever since it was isolated from lumps of graphite in 2004 by Geim and Novoselov et al [1,2,3,4,5,6,7] This success was motivated by its unique electronic, electrochemical, optical, thermal and mechanical properties, leading to its application in a variety of research areas including electronics, sensing, energy conversion and storage, water purification and biomedical applications [1,2,3,5,6,7,8]. Graphene oxide consists of a monolayer of carbon atoms having both (significantly) sp2 -hybridized carbon atoms and (partially) sp3 -hybridized carbon atoms bearing polar oxygen-containing functional groups (OFGs) distributed on its basal plane (hydroxyl and epoxy) and along its edges with regard to jurisdictional claims in published maps and institutional affiliations.

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