National Science Foundation Silicon Carbide Nanowires on Graphene – Synthesis, Characterization and Application Roya Maboudian, University of California-Berkeley, DMR Outcome: Researchers at University of California at Berkeley have synthesized silicon carbide nanowires on graphene and demonstrated their application as robust, high power energy storage materials in supercapacitors. 1 Impact: These materials have a broad range of applications in devices requiring high power energy sources that are reliable over hundreds of thousands of cycles. Explanation: Silicon carbide nanowires have a high surface area to volume ratio and are both electro-chemically and thermally stable. Graphene also has a high surface area, but has the added benefit of excellent electrical properties and flexibility. These materials in concert yield flexible, robust, high surface area materials – ideal properties for supercapacitor electrodes. Supercapacitors store electrical charge on their outer surface, allowing for rapid access to the energy. This in turn results in high power capacity. By focusing on silicon carbide nanomaterials combined with graphene, the cycling stability and electrical performance of the electrode is greatly enhanced. The potential for these materials as robust, compact energy storage materials is great due to their bulk properties, and these applications are under investigation. Silicon carbide nanowires grown on graphene and transferred onto flexible plastic. 1 J. P. Alper, A. Gutes, C. Carraro, R. Maboudian, Nanoscale, 5 (2013) 4114 – 4118.

National Science Foundation Silicon carbide nanowires are grown by chemical vapor deposition on graphene, catalyzed by a thin metal coating. Silicon carbide is well known for its electrochemical and thermal stability and graphene is well known for its conductivity and flexibility. Leveraging these desirable properties with the intrinsically high specific area of the nanowire geometry and planar graphene, an attractive material for supercapacitor electrodes results. In a recent publication robust cycling performance (negligible fade after 10k cycles) with reduced contact resistance has been demonstrated. High Power and Robust Cycling Supercapacitor Demonstrated Roya Maboudian, University of California-Berkeley, DMR Cyclic voltammetry results in (a) demonstrate improved electrical contact for nanowires grown on graphene. The SEM image (b) is a top view of silicon carbide wires grown on graphene. The highly robust cycling performance performance is demonstrated (c). b a c 5  m

National Science Foundation Undergraduate Mentoring and Training in Research Roya Maboudian, University of California-Berkeley, DMR Undergraduate mentoring and training in research has been an important and integral part of the research. Jennie Zheng, an undergraduate researcher, spent the past summer developing synthesis techniques to improve the power densities of these materials by integrating with porous frameworks. Under the tutelage of PhD candidate John Alper, Jennie has contributed greatly to fine tune the synthesis conditions in order to achieve dense films of nanowires on graphitic foams. These results are in the process of being crystallized as a peer reviewed publication in which Jennie’s contributions will be recognized. Jennie Zheng, an undergraduate researcher in the Maboudian lab has been responsible for developing techniques to integrate SiCNWs in porous materials for improved electrode performance. Pictured here, she presents the results of her work over the summer at an undergraduate poster session.