Bulk scale growth of CVD graphene on Ni nanowire foams for a highly dense and elastic 3D conducting electrode Byung Hyun Min, Dae Woo Kim, Kyoung Hwan Kim, Hyung Ouk Choi, Sung Woo Jang, Hee-Tae Jung * National Research Lab. for Organic Opto-Electronic Materials, Department of Chemical and Biomolecular Eng. (BK-21 plus), Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea ARTICLE INFO Article history: Received 25 June 2014 Accepted 25 August 2014 Available online 30 August 2014 ABSTRACT A new and simple method to prepare three-dimensional (3D) graphene foams is developed. It uses 3D Ni nanowire foams as a catalyst for chemical vapor deposition (CVD). Ni nanowires were synthesized on a large scale by the reduction of Ni ions under an applied magnetic field, and then assembled into a 3D film by filtrating a bulk Ni nanowire solution or by pressing Ni nanowire powder. An additional CVD process was conducted to develop graphene on the 3D Ni nanowire foam at 670 °C, which is considerably lower than the conventional growth temperatures of around 1000 °C. The resulting 3D graphene exhibited higher electrical conductivity (17.5 S/cm) as well as a higher specific surface area (145 m 2 /g) due to its highly dense and interconnected structure, with pores on the order of several microns. The 3D graphene foam also exhibited excellent electrical and mechanical proper- ties under repeated mechanical deformations (stretching, bending and folding), demon- strating their potential for use in such applications as the electrodes in wearable devices and electrochemical catalysts. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Three-dimensional (3D) structures composed of a two-dimen- sional carbon sheet (graphene) have been widely applied in a variety of applications, such as in energy-storage materials, supporting matrices for catalysts, chemical sensors and flexible electronics [1–8]. The widespread utilization of 3D graphene for these applications can be attributed to the mul- tiple advantages that 3D graphene possesses over 2D graph- ene: a high surface area, high electrical conductivity, light- weight, and good structural integrity [8]. Of particular note is the macroscopic porous interconnected structure of 3D graphene, which not only has outstanding electrical proper- ties, but also facilitates the introduction of functional materi- als, such as catalytic metals or metal oxides, to the graphene surface by providing more adsorption sites and allowing effective mass transport through its macroscopic void space [2,3,6]. Since the report of enhanced performance across a variety of application as a result of the use of 3D graphenes, consid- erable interest has been directed towards its production using a number of methods. Graphene oxide, which is composed of many functional groups on the graphene basal plane, has been identified as a promising material for processing http://dx.doi.org/10.1016/j.carbon.2014.08.084 0008-6223/Ó 2014 Elsevier Ltd. All rights reserved. * Corresponding author. E-mail address: heetae@kaist.ac.kr (H.-T. Jung). CARBON 80 (2014) 446 – 452 Available at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/carbon