In situ bandgap tuning of graphene oxide achieved by electrochemical bias

Jan 30, 2014

The ability to modulate the physical properties of graphene oxide within electronic components could have numerous applications in technology, WPI-MANA scientists report

Super-strong graphene oxide (GO) sheets are useful for ultrathin, flexible nano-electronic devices, and display unique properties including photoluminescence and room temperature ferromagnetism. Tsuchiya, Terabe and Aono at Japan's World Premier International Center for Materials Nanoarchitectonics (WPI-MANA) are developing novel techniques that allow them to fine tune the of GO, such as , within working components.

The conductivity of GO is lower than graphene itself because of disruptions within its bonding structure. Specifically, the carbon atoms in GO exhibit a blurring of energy levels called sp2 or sp3 hybridizations. In ordinary GO, bonding in the sp2 level is disrupted, and under severe disruption the GO becomes an insulator rather than a conductor. Highly-reduced GO (rGO), with lower oxygen levels, has a near-perfect hexagonal lattice structure with strong bonds and high conductivity.

By adjusting the percentages of sp2 and sp3 domains in GO, Terabe and his team have gained the ability to fine tune band gaps and therefore control conductivity. Current methods of controlling bandgaps in GO are chemically-based, expensive, and cannot be used within themselves.

Now, the team have achieved non-volatile tuning of bandgaps in multi-layered GO within an all-solid-state electric double layer transistor (EDLT). The EDLT comprised GO on a silica glass substrate gated by a zirconia proton conductor. The team triggered a reversible electrochemical reduction and oxidation (redox) reaction at the GO/zirconia interface by applying a dc voltage. This in turn caused proton migration from GO through the zirconia (see image). The redox reaction created rGO, and caused a fivefold increase in current in the transistor.

The rGO retained conductivity for more than one month without further voltage application. Compared with field-effect transistors, the new EDLT uses far less voltage to switch between on and off phases, meaning it is far cheaper to use. This new method for fine tuning conductivity could lead to control over optical and magnetic properties of components, with far-reaching applications.

Explore further: Artificial muscles get graphene boost

More information: T. Tsuchiya, K. Terabe & M. Aono. In-situ and Nonvolatile Bandgap Tuning of Multilayer Graphene Oxide in an All-Solid-State Electric Double Layer Transistor. Advanced Materials, Early View, Article first published online: 16 DEC 2013.

Related Stories

3D graphene: Super-capacitors from sugar bubbles

Jan 24, 2014

Graphene sheets are immensely strong, lightweight and excellent at conducting electricity. Theoretically, macroscopical three-dimensional graphene assemblies should retain the properties of nanoscale graphene ...

Graphene growth on silver

Jan 14, 2014

Users from Northwestern University, working with the Center for Nanoscale Materials EMMD Group at Argonne, have demonstrated the first growth of graphene on a silver substrate.

Recommended for you

Artificial muscles get graphene boost

May 22, 2015

Researchers in South Korea have developed an electrode consisting of a single-atom-thick layer of carbon to help make more durable artificial muscles.

How to make continuous rolls of graphene

May 21, 2015

Graphene is a material with a host of potential applications, including in flexible light sources, solar panels that could be integrated into windows, and membranes to desalinate and purify water. But all ...

Carbon nanothreads from compressed benzene

May 20, 2015

A new carbon nanomaterial – the thinnest possible one-dimensional thread that still retains a diamond-like structure – was created by the controlled, slow compression and decompression of benzene. The ...

Printing 3-D graphene structures for tissue engineering

May 19, 2015

Ever since single-layer graphene burst onto the science scene in 2004, the possibilities for the promising material have seemed nearly endless. With its high electrical conductivity, ability to store energy, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.