Discipline: Chemistry and Chemical Sciences
Subcategory: Materials Science
Valencia A. Danner - University of Maryland, College Park
Graphene is a two-dimensional single layer of carbon atoms. Each carbon atom in graphene bonds with three other carbons, and carries one extra electron which is free to move. Graphene’s physical characteristics allow it to possess great tensile strength, high conductivity, and flexibility. Because of these properties, graphene films have great potential in future electronic technologies. The downside of graphene is that it is very difficult and expensive to mass-produce; the original method to fabricate graphene films is applying sticky tape to graphite (which is essentially billions of layers of graphene) and peeling off the layers. This method is not only time consuming, but hardly acceptable for large-scale production. An alternative method involves using a Graphene Oxide (GO) solution (produced from graphite and acids) and heating it (or reducing) to remove the oxygen and hydrogen atoms, leaving behind a graphene film.
My research project addressed the challenge of developing a method to mass-produce graphene films to use as battery anodes. I tested two fabrication methods using the GO/ reduction method: vacuum filtration and spray gun. Also, since researchers found that adding a metal or metalloid (such as boron) to graphene improves its performance as a battery anode; in addition to GO films, I made GO composite films with nanoparticles of Silicon, Boron, Aluminum, Iron, and Carbon Nanotubes (CNT) to test. I tested two methods to create the graphene films: vacuum filtration and spray gun. I created the GO or composite solutions used in both methods. To produce the vacuum filtration films, I poured the solution over a membrane with 0.65µm pores in the vacuum filter. The membrane and solution were vacuumed for several hours or until the film was removable from the membrane. To produce the spray gun films, I poured the solution into the spray gun fixed with 0.5mm opening tip. I placed a glass slide on a hot plate set to 85-90°C (to quicken the drying time) and coated the glass slide with the solution. Both vacuum filtration and spray gun methods produced uniform, flexible, free standing films. However, both methods contained advantages and disadvantages. After analyzing the differences, I concluded that the spray gun method was better suited for mass-producing graphene films because it was faster and can be more easily scaled up -since increasing the size and number of spray nozzles and glass surfaces is relatively less expensive than increasing the size and power of a vacuum. The next steps for our research include producing more GO and composite films, reducing the films to obtain graphene, and testing them for their conductivity and other properties, which we expect to complete within the next few months. I look forward to publishing the findings with Dr. Liangbing Hu, Dr. Alireza Khaligh, and Ph. D. candidate Mr. Yanan Chen within the next year.
References: Patel Prachi. 2008 Apr 14. How to Make Graphene. MIT Technology Review; [accessed 2015 Aug 1]. http:// www.technologyreview.com/news/409900/how-to-makegraphene/ Mrmak N. 2014 Jun 6. 4 Great Methods to Make Graphene. Graphene-Battery.net; [accessed 2015 Jul 27]. http:// www.graphene-battery.net/graphene.htm Liu Yuanyue , Artyukhov VI, Liu M, Harutyunyan AR, Yakobson BI. 2013. Feasibility of Lithium Storage on Graphene and Its Derivatives. The Journal of Physical Chemistry Letters. 4 (10):1737–1742.
Funder Acknowledgement(s): This work has been supported through the National Science Foundation grant number EEC 1263063, REU Site: Summer Engineering Research Experiences in Transportation Electrification, which is gratefully acknowledged. I also thank my faculty project advisor Dr. Liangbing Hu, REU Director and faculty co-advisor Dr. Alireza Khaligh, graduate advisor Mr. Yanan “Charles” Chen, and graduate staff of BingNano Research Group for their support and guidance provided throughout this project.
Faculty Advisor: Alireza Khaligh,