Electrochemical Device Fabrication

The primary goals of the Center are to develop techniques to make atomically reproducible contacts to single molecules using graphene and carbon nanotube electrodes, and then to use the understanding gained from such systems for applications in energy conversion and storage technologies, sensing, and information technologies.

Electrochemical devices fabricated from exfoliated graphene (top) and CVD-grown graphene (Bottom)

Fabrication and molecular device characterization efforts in the CMI take place in the Abruña, McEuen, Park, and Ralph groups. We are experimenting with a variety of nanofabrication procedures to make devices with well-defined graphene and carbon nanotube electrodes. Many of these device architectures also feature integrated microfluidic channels for varying the chemical composition of the junction in a time-resolved fashion. We have, for example, developed techniques to pattern electrodes from both exfoliated graphene and graphene made by chemical vapor deposition (CVD), made so that a chemical solution makes contact only to the graphene and not to the metal contacts used to test the device (see figure). Our fabrication methods are designed to obtain clean carbon-electrode surfaces and to allow a variety of methods to be used to test their cleanliness.

We have begun to characterize the chemical binding and electrical contact of molecules synthesized to bond in registry to the carbon lattice in graphene and carbon nanotubes.  Electrochemical techniques are particularly useful for this process, as they permit measurements of the electrical connection of molecules to a single sheet of graphene. We have also initiated measurements of electronic properties as the spacing between two graphene sheets is varied, both in the presence and absence of molecules in between.