Metal Deposition on Graphene Layers and Electrochemical Measurements at Liquid/Liquid Interface: Preparation of Graphene-Based Metal Nanostructures

Polarisable liquid/liquid interfaces have been investigated for over 30 years, mainly in the context of ion and electron transfer reactions. Electrical polarisation of the interface between two immiscible electrolyte solutions (ITIES) generates electrochemical potential gradients capable of promoting ion and electron transfer across the molecular boundary. The potential drop across the liquid/liquid boundary is developed over a region of 1 to 10 nm. The nucleation of metallic structures, catalytic activity e.g. hydrogen and oxygen evolution, the assembly of nanoparticles or catalytic nanoparticles have received a great interest in the last years.^1-2

Graphene nanomaterials were prepared in two ways: gravity exfoliation from natural graphite in 1,2-dichloroethane (DCE) dispersion and chemical vapor deposition (CVD) on copper foil. Both types of material were assembled at the interface between two immiscible electrolyte solutions. The graphene materials before and after assembly were characterized by Atomic Force Microscopy (AFM) and Raman spectroscopy. The electrochemical reactivity of assembled graphene materials was probed by model redox species at the ITIES.

In situ electrochemical and spontaneous metal deposition of palladium, gold and silver at the interface assembled carbon nanomaterials were studied. The identification and morphology of the deposited metal was determined using electron microscopy. The 2D graphene-based metal nanostructures effects were studied for the model redox species process at the ITIES.

The graphene-metal composites preparation procedure at the ITIES opens an alternative way to prepare catalyst materials. Deeper understanding of the behavior of model redox couples on graphene is of primary importance in the exploitation of this material in catalytic processes, such as of the oxidation of low molecular weight alkanes to liquid fuels.

1. Fermin, D. J.; Ding, Z.; Duong, H. D.; Brevet, P. F.; Girault, H. H., Journal of Physical Chemistry B, 1998, 102, 10334-10341.

2. Dryfe, R. A. W., Physical Chemistry Chemical Physics, 2006, 8, 1869-1883.